HABITAT CREATION AND ENHANCEMENT
By following design templates set by nature and matched to your location not only do you create something that is in keeping with your surroundings, but also, by ‘working with the grain’ in partnership with nature success is more likely, and less effort will be required to maintain this over time.
Habitat or ecosystem based landscaping and gardening with wild plants involves a holistic approach following and working with the designs created by nature.
Emorsgate have developed a range of habitat based mixture options that can be used to introduce plant diversity to habitat creation and enhancement projects within conservation, landscaping, wildlife gardening or on farmland.
Matching your site circumstances to potential habitat is key to success so we suggest the following approach:
- Assess your site and soil and any pre-existing botanical or other wildlife interest. Compare your site with other similar areas in your locality.
- Highlight any existing habitat or features that are worth conserving.
- Assess whether there are areas that have some merit but with potential for enhancement.
- Identify areas where new habitat can be created from scratch.
Sites that have the most biodiversity usually contain a variety of habitat types. Maximising diversity in a scheme often involves creating complementary new habitats within existing sites as well as developing the main features: for example adding a pond or hedgerow to a grassland habitat.
Animals and insects will frequently require more than one habitat type to obtain the different resources for food and shelter they need to survive and reproduce.
The principle habitat categories in which sowing wild flower seeds can have a role are:
- Meadows and grasslands
- Wetlands and pond margins
- Hedgerow and woodland
- Cornfield annuals
Selecting and sowing the right seeds is however only the first part of the process. The results you achieve in practice will be determined not so much by the seeds you have sown but by site and soil conditions and importantly the way the site is managed. Throughout our website we have tried to give equal emphasis to providing information on management and site selection as we have to the composition of our mixtures.
NVC PLANT COMMUNITIES
The British National Vegetation Classification or NVC is a system of describing and classifying natural habitat types in Great Britain according to the vegetation they contain.
In practice the NVC community descriptions do not translate directly into a corresponding set of seed mixtures that can be sown to recreate the given community as some have tried to suggest. The NVC was not designed for this purpose and many other factors have to be considered when specifying seed mixtures. However since its publication in 1992 it has proved an invaluable resource when creating wild flower and grass seed specifications and mixtures.
Emorsgate have used the NVC extensively over the years to inform the development of the seed mixtures we offer. The following is a guide to the NVC categories that inform the mixtures we offer based upon plant communities that could develop in, or be appropriate to, the circumstances for which in our mixtures are commonly specified.
If you have a particular plant community specified as an objective for restoration do contact us for advice as to the best practical way to try and achieve this.
Most of our seed mixture reference more than one NVC community type. This is a reflection of the fact that firstly a given site and soil type can naturally support a number of communities depending on management, hydrology and other factors; and secondly, that the communities overlap and can change over time from one to another.
MG5 Cynosurus cristatus – Centaurea nigra mesotrophic grassland underlies many of our seed mixture specifications as this is the major grassland type included within the popular, but often loosely applied, category of ‘Old Meadow’ which in turn is the objective of many schemes.
The following list gives examples of Emorsgates’ principal mixtures followed by codes of the NVC categories which have informed their composition.
EM1 EM2 EM3 General purpose meadow mixtures
MG5 MG1 MG1e
EM4 Meadow mixture for clay soils
MG5 MG5a Heavy neutral brown earths over clays/shale
EM5 Meadow mixture for loamy soils
MG5 MG5b Lighter brown earths developed from alluvium and other material often over calcareous bedrock
EM6 Meadow mixture for chalk and limestone
MG5 MG5b CG2 CG3 CG9
EM7 Meadow mixture for sandy soils
EM8 Meadow mixture for wetlands
MG4 Seasonally (winter) flooded Lowland Alluvial Meadows
MG8 Water meadows
M22 Fen meadow
EP1 Pond edge mixture
M22 M23 M27 Mires
MG4 MG8 Flood plain meadows and water meadows
EM10 Tussock mixture
MG1 MG1e MG5 MG9
EH1 Hedgerow mixture
MG1 MG1e MG5
EW1 Woodland mixture
W8 W9 W10 W11 W12
LANDSCAPING AND LAND RESTORATION
Wild seeds have been used in landscaping for some time now and many of the flowery verges seen on some of our newer roads are the result of deliberate seeding and careful management.
Wild seeds have many other applications in landscaping. They may be used in parks, golf courses, beside waterways, along pipeline and cable routes, after mineral extraction, for environmental improvement in urban and industrial areas, on rail routes, and in fact almost any situation involving excavation and construction.
Our general recommended seeding rate for mixtures is 4g per square metre (16kg per acre) and this is the optimum seeding rate for most landscaping situations, giving a seed cost of 10-20p per square metre. In comparison with amenity grasses, wild native plants are attractive, well adapted to British conditions, low maintenance and friendly to wildlife.
As with any seeding, it is important to select the species sown, and their origin, to fit in with the nature of the surrounding vegetation. In most landscaping situations a standard mixture of British origin seed will be appropriate, selecting species that are suited to the prevailing soil type, location and conditions. In areas where high quality natural vegetation already exists it may be best to use seed of regional origin, or local origin, or ‘brush-harvest’ truly wild seed from a nearby donor site.
CONSERVATION AND HABITAT RESTORATION
The conservation of species and plant communities in their ‘wild natural state’ is important. Aside from their intrinsic value and preserving a living record of the past, protected habitats, such as nature reserves, can offer a genetic resource for conservation and restoration projects.
Over the last 30 years, Emorsgate have been able to sample this biodiversity by collecting small quantities of seed from all parts of Britain with the support and co-operation of wildlife trusts and other trustees of natural habitats. The stocks generated from these collections are grown as seed crops on our farms in Norfolk and in Somerset. These crops provide the seed of wild flowers and wild grasses we now offer for sowing in both conservation and landscape projects.
Sowing wild flower and grass seeds is now widely accepted as a conservation strategy: a way to assist natural plant distribution, to repair and re-connect habitats, for example for:
- Habitat repair through local plant species re-introductions
- Extending the size of habitat fragments to improve their viability
- Linking isolated habitats to improve their viability
- Creating wildlife corridors to promote the wider dispersal of mobile species
- Creating new habitat to compliment existing habitat
- Buffering sensitive habitat against threats from adjoining land use
- Enhancing the biodiversity of depleted areas
- In-situ plant species conservation
- Targeted insect and animal species conservation by providing food plants or habitat.
Sowing wild seed was not always viewed as necessary in conservation – why?
Wildlife conservation through most of the twentieth century focused on protecting and monitoring existing wild plant and animal communities in nature reserves and other designated conservation areas. Because of the dedication and enthusiasm of individuals and wildlife trusts many habitats and species that would have been lost have been preserved for future generations.
In spite of all this effort, reports published in the 1970s highlighted a dramatic and continuing loss of natural and semi-natural habitat in the wider British landscape through habitat destruction, degradation and fragmentation: 97% of flower- rich grassland for example had disappeared in just a few decades. These reports did stimulate an interest in sowing wild flower seeds in landscape situations – this however was not viewed at the time as conservation; just one way of putting something back.
More effort has subsequently gone into actively managing habitats to stimulate recovery both within nature reserves and in the wider countryside but by the 1990s it was becoming clear that traditional conservation strategies and natural regeneration were not themselves sufficient to stop the on-going losses of habitat and species biodiversity. Alarmingly, reports also started appearing showing a significant decline of more common plants and animals (like the common house sparrow) and not just of rarer species on endangered lists.
The key realisation is that losses of habitat in the British countryside has progressed to a point where wildlife is left clinging on in small fragmented pockets of land (often nature reserves) and many of these habitats are too small to remain viable in the longer term. Furthermore, these habitat islands are isolated from each other by distance, by ‘sterile’ farmland or urban concrete such that recovery by natural dispersal of seeds or animals is unlikely or impossible.
A more pro-active approach is needed, and as part of this, sowing wild seeds is a practical strategy that can at least overcome the limitations arising from restricted natural dispersal of seeds.
FARMLAND AND AGRI-ENVIRONMENT
Wild seeds are the means by which lost diversity and habitat function can be delivered back on to farmland and restore the countryside.
The seeds we offer are the key to restoration for creating habitats which provide the essential resources (especially year-round food, shelter and nesting places) that wild pollinators, birds and other farm wildlife need to survive and breed successfully.
We offer a wide range of options for sowing to achieve Countryside Stewardship scheme objectives such as:
- Creation of species-rich grassland including wild flowers
- Enhancement of existing grassland with wild flowers
- Creation of grassland rich in pollen and nectar
- Creating tussocky grassland and beetle-banks.
- Sowing buffer strips, margins and field corners
Emorsgate seed mixtures: The seed mixtures we offer in our standard range offer the best possible options for sowing diversity.
Farmland & Stewardship mixtures: We also offer an alternative range of mixtures specifically designed for farmland applications where constraints of scale and budget are important.
Bespoke mixtures: We can also advise on and quote to supply seeds tailored to your particular requirements or to the specifications provided by your farm advisor.
Why do we need sow wild seed on farms?
After the food shortages and rationing of the second world war came a concerted push to maximise agricultural production in the UK through the intensification of farming and the use of fertilisers and agro-chemicals. This policy was backed by government grants to bring marginal land ( wildlife habitats) into production.
This intensification bought farming into conflict with wildlife and resulted in the now well documented catastrophic decline in biodiversity of both plants and animals in the countryside. The consequences of industrial farm intensification went deeper than just loss of wild plants and animals, it affected landscape quality and ecosystem function – threatening the sustainability of farming itself.
Fortunately this state of affairs has been acknowledged by government agencies and by the farming community and action is being taken. Government through schemes like countyside stewardship, conservation groups such as the RSPB and wildlife trusts and farmer led groups like FWAG and the Game and Wildlife Conservancy are all working hard to put farming and wildlife back to a balanced co-existence.
Many early initiatives sought to reverse past damage by simply removing or restricting farming practices that were the cause of the declines. In some cases this is all that is needed; as in the recovery of birds of prey after DDT was banned. For less mobile plant species, whose decimated wild populations have become fragmented and isolated, stopping the application of artificial manures and herbicides is not by itself enough.
Grassland plant communities for example do not naturally regenerate as there are frequently no remnant populations of plants to act as an inoculum’ and soil seed banks have long since decayed (grassland perennials unlike arable weeds do not generally maintain as long lived seed banks in the soil). Experiments where Dales meadows were returned to ‘traditional’ management saw no real recovery in species diversity even after 15 years unless long distance plant distribution was facilitated by the sowing of seeds. Plants sit at the beginning of the natural food chain: once plant diversity is restored animal and microbial diversity can also return and ecosystem function can be restored.
Gardens in all their forms are for many people an opportunity to connect with the environment, to commune with nature in an intimate and personal way that is only possible in the familiar territory of our own back yards. The way we relate to and use our gardens reflects how we as individuals regard the world.
Wild life gardening has been taken to mean many things. For some it simply means encouraging wild birds with feeders and nest boxes. For some authors wildlife gardening is a quest for the holy grail of biodiversity, a game of numbers, counting bugs and all that creeps crawls and slimes.
The Emorsgate approach to wild gardening starts, as does most gardening, with the aesthetic beauty of plants. Firstly an appreciation of the natural design and beauty of wild plants ‘as mother nature intended’ un-distorted or improved by man or science. Secondly, a use and appreciation of plants in natural planting schemes based on wild plant communities, using and building on the harmonious co-existence of plants in nature as a model and example. Put another way it is an opportunity to bring the natural plant groupings of the countryside such as primrose bluebell and red campion from a woodland glade into our garden. A key to this approach is allowing nature to be an equal partner in the design and management of our garden.
All gardens large or small, especially those which contain a variety of plant forms: lawn, herbs, grasses, shrubs , hedges and trees, make excellent habitats for wildlife both individually and networked with their neighbouring gardens parks and verges. Only plots set to tarmac concrete patio and decking managed with weedkillers fail. There are no real goodies and baddies in the plant world and both wild and cultivated forms have value and may be grown together in a garden. Growing wild plants however does bring an extra dimension to gardening : the understanding of, connection with, and aesthetic of nature. Aside from these esoteric matters there are some important practical and other side benefits to this approach. By working with natures designs, for example in creating a meadow, you are following a planting design that has endured centuries, with plants that work together.
SITE SELECTION AND SOILS
The plants and plant communities which grow on a site are to a large extent governed by the characteristics and location of the site and soil in which they are rooted. Plant species have evolved strategies to exploit different combinations of climate, soil conditions and disturbance by animals or man: some species have specialised to thrive in particular conditions such as occur on chalk soils, other species are more generalist. For any set of conditions there will be species that thrive and survive, and others which do less well or fail; through this process a natural balance between species is established. Recognising and understanding the characteristics of your site and soil is clearly useful in deciding which species are most likely to do well.
Work with nature: The most rewarding approach to using wild seeds is to work with nature. If you aim to sow a selection of species that are naturally suited to your soil and site conditions, and if you manage the resulting plant community sympathetically allowing natural selection to determine the balance of species appropriate to your site, you have the best chance of attaining the maximum potential from your site and with the least effort. The alternative gardening approach by comparison requires a struggle for control with nature to impose a specific idea of aesthetic and balance that may have no basis in nature.
Plant assessment: Much can be learnt from looking at the plants already growing on site or on similar soils and situations in the locality. A preliminary assessment of local vegetation should be undertaken at an early stage to establish what type of plant communities and approaches are likely to be suitable, as well as identifying any pre-existing habitat or plants that ought to be retained and conserved.
Soils and fertility: Of the factors that influence plant community development, soil characteristics and in particular the fertility and acidity of the soil are probably the most fundamental from the point of view of specifying and using wild seeds. The reason for this is that there is a generally observed principle that the most productive fertile sites and soils tend to have the least potential for plant diversity, whether open grassland, woodland or wetland. Changes in light or water levels will change the type but not necessarily the number of plant species that grow well, but increases in the nutrient status of a site (such as the addition of fertiliser to flower-rich grassland) leads directly to a loss of diversity as the additional resources fuel the growth of the most competitive components at the expense of others. For this reason the emphasis in the following notes will be biased to a discussion of soils and their importance to wild flower seeding.
Understand site potential and limitations: Unfortunately whilst all sites are capable of supporting a naturally balanced plant community, not all sites have the same potential for supporting a diversity of plants, or an attractive range of plants. Where a choice of soil or location is available or can be engineered by earthmoving and land forming (eg in road building) it is useful to be able to identify or specify the most suitable.
Where the choice of soil and location is fixed then understanding the potential or limitations of the site will inform expectations as to the results that can be achieved and the effort required. This may include a decision as to how suitable or cost effective the site is with regard to the desired outcome.
SOILS AND SOIL FERTILITY
Soil characteristics, especially those which affect productivity, have a controlling influence on the diversity and balance of plant species on a site.
The soil characteristics that are most important are:
• texture and structure
• pH acidity/alkalinity
The physical character of soils is determined by the balance of clay, silt and sand particles and by the organic humus content of the soil.
For practical considerations soil texture and related soil structure influence soil workability, drainage and management.
For the purposes of choosing a seed mixture or a planting plan a detailed soil textural analysis is not required. A general understanding of the type of soil on a site, for example whether it is a heavy wet clay, or a light free-draining sand, is all that is required. Many soils in gardens, landscape schemes and meadows are loams: a mixture of clay, silt and sand with none predominating.
Some guidance as to soil structure and associated mixture choices can be found alongside the descriptions of our meadow mixtures for different soils.
The most diverse grasslands in Britain are usually associated with soils of low fertility that have not been agriculturally ‘improved’ by additions of fertiliser. In conditions where nutrients are in short supply niche opportunities arise for a wider range of specialist plant types, each species having its own strategy for scavenging the resources it needs.
Assessment of fertility
For most situations the best assessment of site and soil fertility can be derived from knowledge of the history of a site and observation of the vegetation growing there and in similar conditions in the locality. For example the following are all indicators of above average fertility:
- the site is a garden or farmland that has been cropped and fertilised in the past
- the soil usually produces good crops and grass grows well
- there are weeds which indicate fertility: nettles, docks, cleavers, thistles
- the soil is deep and well structured
Chemical analysis of soil fertility is a complex subject and is often of limited practical use for wild flower growing. There is for example no simple way of assessing the ability of a soil to supply plants with the most important soil nutrient Nitrogen, and most established soil test methods have been developed to guide farmers and growers as to how much fertiliser to add to obtain maximum crop yields. Within the 0-9 range over which farm test results are classified the natural levels of most interest for diversity are found in the lowest 0 or 1 class.
Soil phosphorous (P): The phosphate status of soil is considered to be the most useful chemical indicator of fertility and thus potential plant diversity. This is not because phosphorous by itself can greatly enhance productivity (= low diversity), but that its status is frequently the factor that limits plants ability to exploit other resources (principally Nitrogen).
Soils in Britain naturally contain limited amounts of P, and species rich grassland communities are typically associated with soils with a P index of 0 to 1 (15ppm or less). Human activity: human and animal wastes, the addition of basic slag and artificial fertilisers have together augmented the level found in gardens and farmed land to a level 3 or more (many times higher than is ideal for creating diversity). Unfortunately once raised soil P levels decline incredibly slowly, so slowly in fact that elevated P levels are used by archaeologists to detect ancient settlement patterns and abandoned farmsteads – these often reveal themselves as patches of nettles which thrive on high phosphate levels.
A variety of techniques to return fertility to natural levels have been tried. All, with the exception of drastic soil removal, are of limited or variable success.
Weathering / leaching of soil: soluble nutrients like nitrates are lost quite quickly from soils. Insoluble minerals like phosphorous however are only washed out of soils with very high concentrations (index 5+).
Losses occur most rapidly from sandy soils with low organic content; soils with high clay or organic content tend to hold on to minerals. Leaching as a strategy is not recommended as losses of minerals (e.g. nitrates) from soils to watercourses is a major source of pollution.
Repeated removal of bulky crops: cropping may mop up a short term surplus of nitrates but have little impact on long term reserves of phosphates. In practice any significant reductions in P levels require years/decades of continuous removal.
Deep ploughing to bury nutrients: where the topsoil layer is shallow (<20cm) and overlies poor subsoil deep ploughing can bury and dilute the nutrient store of the topsoil. However as the store of nutrients is redistributed and not removed observed benefits of this technique tend to be short lived as after 4 years competitive plants will root deeper to access these reserves.
Adding material to dilute nutrients: adding materials such as chalk rubble or crushed concrete to the surface to bury or dilute nutrients can produce interesting results. However as with deep ploughing diluting the nutrient pool often has only a temporary effect. Even where depths of 50cm+ (1 tonne/m2) of chalk are laid over good soil, deep rooted plants will eventually find their way through. This approach however can yield some interesting results where the site is not too fertile to begin with and the added material, as with chalk, also changes the soil chemistry and structure.
Land-forming to remove topsoil: this is the only truly effective way of removing nutrient stores from a site. As this approach is irreversible and expensive it is not for the fainthearted. Before embarking on this approach it is important to consider the long term implications for the site and assess whether there is any potential to damage buried archaeological features. This approach is most appropriate to landscape projects where overall there may be a shortage of good topsoil so that re-profiling can be arranged to build up topsoil on amenity areas where it is needed and remove it from areas designated for permanent wildflower mixtures (e.g. road embankments).
One of the most obvious changes of vegetation character is that between acid soils with heather and gorse, to alkaline chalk and limestone soils with its profusion of flowering plants. A pH test of your soil can be useful in confirming with other observations the character of your soil.
Most natural soils fall in the range pH 5 – 7.5.
pH >7.0 Calcareous
pH 6.5-7.0 Neutral-calcareous
pH 6.0-6.5 Neutral
pH 5.0-6.0 Acid-neutral
pH <5.0 Acid
Calcareous soils with a pH 7.5+ potentially support the greatest diversity of plant species. The most diverse calcareous grassland containing chalk or limestone specialists will be found on thin soils in which the chalk/limestone is significant and obvious.
It should not be assumed that soils overlying chalk or limestone are calcareous as the topsoil could be derived from glacial drift which is naturally more acidic, or the surface layers may have acidified. Generally over time soils in Britain tend to become more acidic as a result of the acidifying effects of rainfall, leaf fall and natural soil processes. Some upland limestone meadows of the Pennine dales perhaps owe their floral richness to historic liming reversing the acidifying effects of high rainfall.
Clays and other soils not derived from calcareous bedrock tend towards acid or acid-neutral but may have had their pH raised by past liming.
Acid soils generally support a lower diversity of species as fewer species have evolved to cope with acidity and its effects.
Organic humus content: Organic matter in the soil is essential (even for most wild plants) for soil structure and the retention of moisture and minerals. Raw soils such as subsoils, damaged soils, manufactured substrates for roof schemes and quarry reclamation materials which lack organic material and structure may have physical problems limiting plant growth. Remediation may be required before sowing which may include the addition of organic material as well as deep ripping to break any compaction.
SECONDARY SITE FACTORS
Drainage and Hydrology
Plants vary considerably in their ability to tolerate drought or water-logging. The seasonality of flooding or drought on a site also has a big effect on plant communities, and is quite a complex subject.
Wet soils: From a practical point of view wetland areas if not overloaded with nutrients from adjoining land can produce valuable and diverse habitat and developed and can be sown with a species selection such as our Pond Edge mix EP1. The kinds of plants that establish readily from seed tend to be marginal plants rather than true aquatics: they possess a degree of adaptation to flooding and waterlogging but do not need to be in water to grow. Seasonal flooding may have practical implications for timing of sowing and establishment: this may typically favour sowing in spring to get good establishment before the winter rains.
Drought prone soils usually develop characteristic plant communities. Drought can be caused by soils that drain feely (like sands) and cannot hold moisture (eg low in organic matter). Drought can also occur where the depth of soil is very shallow (as in green roof schemes) and cannot hold enough water in reserve between showers (particularly in drier parts of the UK). Plant species that cope with surface drought by deep rooting can survive in the first situation, but may not cope where the roots are restricted and cannot grow to find water. In the latter case plants which seed freely and can regenerate from seed after drought (like annuals) can avoid drought in this way.
Sowings on dry sites are usually more successful in autumn giving a longer period for root establishment ahead of droughts in summer.
Shade and Tree cover
Apart from the obvious effect from shading, trees can also effect ground vegetation through their roots taking moisture, and from autumn leaf-fall which smothers plants and prevent seedling growth. Mixtures of species suitable to these areas like EW1 woodland mix can be sown Because of the effects of trees establishment of sown species may take longer and be more patchy than sowings in the open and this should be taken into account when devising schemes. Long established tree and shrub cover may also cause localised soil enrichment either directly from leaf fall, or as in old parkland as a result of cattle congregating beneath – such areas are best avoided if possible.
Steep slopes and banks
Wild flower mixtures can produce good results on embankments, the additional drainage and shallow soils from years of soil slippage sometimes gives better results than comparable sowings on the flat. The results obtained from a sowing may vary depending on whether the slope faces North or South.
Initial establishment on steep slopes can be tricky as seed is prone to washing off in heavy rain or being exposed to drought in summer.
A weed is often defined as “any plant growing in the wrong place”, in other words any ‘uninvited’ plant that is not a planned crop, landscape or garden plant. In the context of sowing wild seeds there is no reason to regard all unsown arrivals as weeds that need to be dealt with; considerable effort and worry can be saved by targeting only those weeds which by virtue of their competitive nature would, if unmanaged, cause problems.
There are two circumstances in which weed management will be faced. The most important is in clearing weeds in preparation for sowing. The other is dealing with (hopefully occasional) weeds that appear after sowing having perhaps escaped pre-sowing controls or invaded later.
It is useful to be able to identify which ‘weeds’ or weed types are benign and can be tolerated if managed, and which are best controlled or avoided.
Annual weeds such as groundsel, knotgrass, fat hen and black-grass usually have little or no long term effect on a sowing provided that the soil is not too fertile. Most soils contain a large store of weed seeds and some annual weed growth should be expected even with good preparation. The pressure from annual weed infestations can be usefully reduced by fallowing and adopting the stale seed bed technique prior to sowing. Annual weeds that appear in perennial grassland and meadow mixture sowings will be eliminated by the end of the first season simply through repeated mowing.
Pernicious perennial weeds including well known weeds such as nettles, thistles, docks, couch grass and brambles can compromise the results of a sowing by crowding out sown species. These weeds may also devalue a scheme through their perceived association with neglect and poor management. A variety of methods can be used to control perennial weeds. It is always best to get control of problem perennial weeds before attempting to sow as selective control after sowing is difficult and laborious. Modest numbers or discrete patches of problem perennial weeds are usually manageable. Significant weed problems, or the presence of particular weeds, may however reveal a site that is difficult to change and unlikely to produce good results (eg nettles which indicate high soil fertility).
Competitive perennials are another significant group of species not usually regarded as weeds that can compromise a sowing by virtue of their strong competitive growth. Species in this group include tall oat-grass, cocksfoot, Yorkshire fog, creeping bent, ryegrass, white clover and some other legumes.
How each of these species is regarded and dealt with very much depends upon the circumstance. The tall grass, cocksfoot, for example, in moderation is a valuable component of tussocky grasslands, however, before sowing a fine grass and wild flower mixture it may be necessary to exclude it from the site (if only temporarily). Sometimes whether the species behaves as a weed or not is a function of soil and site factors. Clovers for example are more likely to cause problems on soils with high phosphorous and low nitrogen status, and tall tussocky grasses may only spread and dominate if the site is not managed (mown) rigorously.
In general, species in this group should be avoided in mixture specifications, or used with caution! Even on sites where ‘weedy’ species are ecologically appropriate they will typically appear uninvited in more than adequate numbers without needing to add seed.
The presence of ‘alien’ species (ie species that are recent non-native introductions to the British flora) are not necessarily a cause for concern. Many, like Michaelmas daisy in urban sites, can be accommodated as part of the diversity of a site and others like woad and opium poppy echo past land use and are a part of a site’s history.
Problem introduced weed species like giant hogweed, Himalayan balsam or Japanese knotgrass however should be categorised with other pernicious perennial weeds and dealt with accordingly.
Weed control in preparation for sowing
Weeds can be controlled by mechanical removal or exhaustion. Removal by hoeing, digging out or repeat cultivation is an effective control for most annual and biennial weeds but less effective (as most gardeners know) for perennial weeds with underground rootstocks. It is possible to exhaust persistent perennial weeds by repeated removal, but it is easy to allow a weed to recover if repeat cultivation is delayed for any reason (e.g. unsuitable weather). Other strategies like fallowing, or covering the ground with plastic mulch are usually essential to success.
The aim of fallowing is to leave land exposed to provide an opportunity to deal with weed problems. During the fallow period a number of strategies can be followed to clean the land depending on the soil type and weed burden. Deep ploughing will reduce perennial weeds by causing a proportion to rot, and by producing a temporary check to their vigour as they are forced to re-grow to the surface. This burying must be followed by summer fallowing to be fully effective as a weed control measure. The aim of summer fallowing is to expose and dry out the rootstock and rhizomes of established perennial weeds, and to exhaust their growth reserves. On lighter soils the roots can be dragged out with a harrow or rake as the soil dries. On heavy soils the land should be very roughly cultivated or ploughed in spring to leave the maximum surface area and depth exposed. The resulting large clods and ridges should be left to dry out completely in the spring and early summer to ‘bake out’ the perennials.
The Stale Seedbed technique
The “stale seedbed technique” can work well to reduce competition from annual weeds whose seeds will remain in the soil after clearance. This method involves preparing a seedbed then delaying sowing to allow a flush of weed seed germination from the surface layers. This flush of weeds is then killed, by surface cultivation/ hoeing, before sowing your seed mixture onto the cleaned “stale” seedbed – the surface of which now has a reduced weed seed burden. Timing and weather conditions are important for success. The soil must be moist and warm enough to encourage weed emergence. The weeds must not be given enough time to set new seed or develop new persistent root stocks. Cultivation should be shallow to avoid bringing fresh buried weed seeds to the surface.
Weed control in aftercare of established sowings
Perennial weeds in grassland may be kept in check if they are cut, grazed or grubbed out at the right time, and if the grassland is well managed.
For many perennials the optimum removal strategy is to take away as much of the plant as possible at a point in the season when it has its maximum commitment of its reserves exposed (above ground). For thistles this occurs in July when the plants have their underground stores and growth potential committed to rapid above ground growth for flowering and seeding. Thistle plants should not be tackled too soon as this will divert their effort into renewed root growth: aim to cut hard as they start to flower but before they set any seed. Cutting too late in the season allows weed seed dispersal and also time for the plants to put down root stores once again. The same principles can be applied to other weeds.
Good grassland management is important to keep control of weeds. Overgrazing leaves large gaps in which weeds like ragwort can establish. Zero grazing or mowing on the other hand allows coarse and woody weeds, brambles and scrub to develop.
LOCAL SEED AND ECOTYPE CHOICES
For each order Emorsgate endeavor to supply seed stocks that are as closely matched in type and origin as possible to the intended use.
To be certain that the wild flower and wild grass seed we offer for sale through our website and by mail order is genuinely wild we collect stock seed ourselves from wild plant populations around Britain. These stocks are then grown as seed crops on our farms in Norfolk and in Somerset.
We now hold a large collection of species collected from a wide range of sites and locations. Using this resource we aim to be able to offer representative forms and ecotypes of all the species we sell. As a result the seeds we offer individually and in mixtures are generally appropriate for sowing throughout the British Isles.
Realistically however, as seed growers, we can only ever hope to offer a very small fraction of the rich diversity that makes up British flora. We will never be in a position to offer, off the shelf, mixtures in which all the components are precisely matched to each individual location or habitat.
Practical Options for intended use
The intended application of wild seed will have a great bearing on the appropriate choice of seed stocks: factors such as the scheme objectives, its location and the proximity to any sites of botanical or conservation interest or sensitivity.
For most general landscape applications we believe that British native wild origin flowers in combination with wild origin grasses and some appropriate amenity grass varieties offer the most suitable, and economic solution and is the basis on which our mixtures are formulated.
For conservation projects, where origin is a high priority, we can offer a range of alternative options and strategies and would be pleased to offer advice or mixture suggestions tailored to your particular requirements.
Options can include:
- Specifying 100% wild origin grasses as well as wild flowers
- Regionally based custom mixtures
- Local seed harvesting from a suitable donor site
- Contract growing seeds collected from your site
The full range of options with regard to seed origin are discussed in more detail in the associated pages. Wild flower seed origin and grass seed origin options are outlined on separate pages as the issues that influence choices differ in some respects.
Wild flower seed origin options
The following notes explain our practical policy of matching origin to use and the additional options that may be available. (The sections are numbered to make it easier to refer to these options in any correspondence or requests you may put to us).
Wild flower species
All the wild flower seed stocks we offer originate from wild plant populations in Britain. The wild plant communities we collect from are botanically diverse and matched to the habitats for which we expect ours seed to be sown (eg meadows). With a few exceptions the seed we sell has been grown from these stocks on our farms near King’s Lynn and Bath. For each of the species we sell (as individual items or as components in our mixtures) we publish the county from which our principal wild stock seed was first collected.
‘Local origin’ For some species we have stocks available from more than one county origin.
Where we can, we try to use the most appropriate seed stocks matched by habitat and region when mixing batches of seed for special projects and mixtures. In practice whilst we now have almost 1000 collections from all parts of the UK, for most orders to mix a comprehensive range of species we will need to use some ‘local stocks’ and some from other UK regions. The selection of stocks for these orders will be determined (by us) subject to availability and choice in our stores at the time of ordering.
Where there is a particular requirement that the seeds for a scheme be of matched origin by habitat or region’ for example when sowing near to botanically sensitive sites, there are two options:
• We can make collections from your locality and grow these seeds on contract on our farms. This process requires a lead time of 2-5 years. We are happy to quote for this service; as a guide seeds produced on a reasonable scale in this way cost on average twice our standard list price.
• We can allocate existing stocks from our collections or crops to your project, increasing dedicated production of key stocks (where lead times allow). As a guide special origin orders cost an additional 50% on top of the standard list price reflecting the smaller scale productivity and limited availability of these stocks. Special origin seeds may be reserved by placement of an order and payment of a reservation fee (terms and quotes available on request).
For example: we have supplied locally collected seeds grown on contract for the Baldock bypass in Hertfordshire, and for Samphire Hoe in Kent (part of the channel tunnel construction project). We can offer mixtures for the Pennine dales using seed origins from meadows in Yorkshire, Co Durham and Northumberland, or mixtures using stocks from the Cotswolds.
Agricultural varieties of legume and flower species where available are usually of non British origin and the result of a long history of cultivated plant breeding selection. They differ from the corresponding wild forms, usually being more robust, vigorous and showing poor long term persistence. The exception to this is the variety ‘Kent wild white clover’ but this species is of limited application in wild flower mixes. WE DO NOT USE THESE VARIETIES IN OUR WILD FLOWER OR MEADOW MIXTURES.
Grass seed origin options
The following notes explain our practical policy of matching origin to use and the additional options that may be available. (The sections are numbered to make it easier to refer to these options in any correspondence or requests you may put to us).
For most landscape applications the only practical strategy is to use an appropriate combination of wild origin grasses and amenity varieties. The reasons for this are:
• When carefully chosen, amenity varieties of grasses have equivalent growth form to wild forms: many are derived without alteration from wild populations. (This is not generally the case with agriculturally bred forms eg of Ryegrass and Cocksfoot)
• True wild origin grasses cost many times more to produce as they do not have the economies of scale associated with internationally traded grass seeds – most schemes cannot justify this additional cost, or the money is better spent on wild flowers.
• Supplies of wild origin grass are very limited.
• Large volumes of amenity grass seeds are sown in landscape contexts every year; their use in wild flower mixtures, if not ideal, has minimal environmental impact.
In our standard mixtures we use British native wild origin grass seed where possible and where no suitable amenity forms exist. Otherwise we use the most appropriate amenity varieties available.
We do have limited stocks of wild origin grasses for most key species which may be specified for special schemes subject to availability. The price of genuine wild origin stocks are generally 10 times that of commercial grass sources.
For botanically sensitive projects there is the option, as with wild flowers, for us to contract grow and supply seed produced from wild collections made in your locality
USING CORNFIELD ANNUALS AND OTHER SPECIES AS NURSE COVER
In certain situations it is necessary or desirable to obtain a rapid establishment of ground cover. For example:
• To stabilise soil surface of engineered banks
• To effect a rapid green cover for aesthetic reasons
Meadow and grassland mixtures are mainly composed of slow growing perennials which, sown at the required low seeding rates, are designed to take several months to attain full ground cover. Pushing the establishment of these components by increasing the sowing rate, or adding fertilisers is not advisable as in most situations it would seriously compromise the end result. An alternative approach is required.
The best solution currently available is to sow a temporary cover of additional species in combination with the main mixture; these species should have the following properties:
• Short term: Rapid establishment on a range of soils types
• Medium term: Not too competitive, and not a nitrogen fixer (not clovers & legumes)
• Long term: Annual or short lived life cycle so will not persist in established grassland
This technique borrowed from agriculture is called sowing a nurse cover crop. Potentially a wide variety of seeds could be used in this role including Cornfield annual wild flower mixtures, annual crop grass eg. Westerwolds Ryegrass and other species such as wheat or barley have also been tried.
Generally nurse species or mixtures can be applied at 2g/m2 in addition to the main sowing of 4g/m2 (giving a combined sowing rate of 6g/m2).
Some degree of compromise is inevitably associated with using two sowings together each to achieve a different objective; careful planning and aftercare will minimise this.
Cornfield annuals as a nurse cover
Meadow mixtures which contain perennial grasses and wild flowers take at least one full growing season to establish full ground cover, and these perennials usually only flower in their second season.
For quicker results when sowing a meadow mixture one option is to combine sowing meadow seeds with a cornfield annual mixture as a temporary nurse cover. This will help fill space and to provide some flowering colour and interest in the first season.
When using this method both mixtures are sown together at the same time on to a clean, prepared, bare soil seedbed. Sow the perennial meadow mixture at its full normal sowing rate (4g/m2 as you would when sowing without nurse cover) as this will deliver the long-term ground cover and diversity. Add cornfield annuals to this up to the full sowing rate for cornfield annuals sown alone (2g/m2) – total combined sowing rate up to 6g/m2.
A cornfield annual mixture can be very successful as nurse cover. The main advantage of using cornfield annuals is that the mixture will give a colourful display of flowers in the first summer. Against their use are their cost and the disappointment that follows their disappearance the following year!
We have seen some excellent results following the use of cornfield annuals. It would seem that the growth of the annuals in the early summer can suppress weed growth, and moderate the vigour of the faster growing perennials and grasses to produce a more open and balanced sward. Yellow Rattle also has a better chance to complete its (annual) life cycle under this regime.
Note: It is very important, particularly on fertile soils, that the annual growth is cut back as soon as flowering declines or as soon as the cover vegetation collapses (usually late July from autumn sowing; early August from spring sowing). The cuttings are usually substantial and must be removed. This cut will reveal the developing meadow mixture and allow it to grow and develop into the autumn unhindered. A delay in cutting will compromise the main sowing, particularly if the cover vegetation has collapsed. Do not wait for the annuals to set seed, there is no point as they cannot grow in established grassland.
USING YELLOW RATTLE TO INCREASE SPECIES DIVERSITY
Yellow rattle is an attractive, semi-parasitic, grassland annual. In the past this plant was a serious pest for farmers as it weakens grasses and as a result can reduce hay yields by as much as 50%. In a landscape or garden context however, this suppression of grass growth is welcomed as it produces a better display of wild flowers and eases the mowing required.
Yellow rattle germinates late February to early March, flowers in June, and sets seed in July. At the end of each growing season as the annual yellow rattle plants die away they leave behind gaps into which new wild flowers can establish. As a result, wild flower seed sown into an existing sward will establish more readily in areas where yellow rattle already does well.
For a description of the plant and to order seed go to the yellow rattle species page.
Getting yellow rattle started
Yellow rattle establishment can be unpredictable and plant numbers may take two to three years to build up, this will depend upon the sowing rate chosen, and site conditions.
For good results, the following points are essential:
Yellow rattle will not thrive in all grassland. The most suitable sites for yellow rattle will be managed grassland of low to medium fertility that contains a balanced sward of finer grasses not dominated by coarse or vigorous grass (ryegrass, cocksfoot, tall oat-grass or couch). Grassland that is the result of sowing a meadow mixture will have suitable grasses, as will finer turf in gardens and meadows. Yellow rattle often fails to take in ryegrass leys and neglected, over-grown or tussocky grassland.
Cut or graze the sward in the autumn, aim to keep the grass short (40-50mm). Graze or mow before and after seeding as needed.
Create gaps across the site with exposed soil for yellow rattle seed to germinate in. This can be achieved by autumn/winter grazing with stock (their hooves open the sward), or mechanically by harrowing or raking, aiming to expose up to 50% bare soil.
Timing: yellow rattle seed must be sown in the autumn as it needs prolonged chilling through the winter to trigger its germination the following spring.
Sowing rate: yellow rattle seed should be scattered onto the prepared surface at a rate of 0.1 to 1 g/m2.
Yellow rattle may be sown as a component of meadow mixtures on to a prepared seedbed. First year meadow management (mowing) can compromise seed set of yellow rattle. To be sure of getting yellow rattle in the second year, it is best to re-sow yellow rattle in the autumn of the first year (as above). Where cornfield annuals have been sown as a ‘nurse crop’, yellow rattle has more opportunity to self-seed.
ADDING DIVERSITY TO GRASSLAND AND OTHER HABITATS
Clearly the more diverse and varied your site is the greater the diversity it can support. Sites with wet ditches and dry banks, with open areas in full sun and shaded margins, will have a greater overall potential and can be sown and managed in different ways. If you have an opportunity to make provision for this by planting trees or creating or enhancing features like ponds or wetland areas this will be of benefit overall. As described in the section on soils the productivity and fertility of your site will have an over-riding influence on the diversity your site can support. The discussion in this section however will assume that the soil character, potential and limitations are ‘given’ and will focus on how to get the best from each site.
Good management that follows ecological principles to work with nature is the best route to obtaining good and sustainable results. Elsewhere we describe how to best match your sowings and expectations to your site conditions, and practical ways to achieve this. The following note discusses how and why these methods are important to maintaining plant diversity.
The act of introducing species to a site by sowing seeds is a way of assisting the dispersal and regeneration of diversity. Without this assistance many species may never arrive, or arrive only by a chance event and probably too late to have much chance to establish as ground cover is already complete. Natural regeneration by naturally dispersed seeds or from the soil seed bank is often suggested but for many sites this approach has limitations.
Natural Seed Dispersal
With the exception of wind dispersed species like dandelions, willowherbs and orchids the dispersal rates of most species is very slow: only a few metres per year. Additionally, after a century of agricultural intensification and urban development, many wild plant populations are now very isolated or remote from new sites and seed is prevented from moving even slowly by distance or sterile barriers of crops and tarmac.
Soil Seed banks
Many common weed species are adapted to exploit regularly occurring gaps in disturbed or cultivated habitats. These species overcome the limitations of dispersal over distance by having a persistent bank of seeds in the soil available whenever a suitable gap opens. These species may need no assistance and will naturally regenerate unless they have been absent from a location for many generations.
Species of more stable communities like grassland and woodland in which disturbance opportunities are infrequent tend not to invest resources into viable seed banks and rely more on recent seed fall from plants close by to colonise gaps. Where a plant species is abundant in a locality and sets good seed it may colonise naturally, but for many locally scarce species some assistance is required.
Introducing seed or moving it from one part of a site to another is a good way of overcoming natural barriers to colonisation (or at the very least speeding the process up). As the establishment of new plants from seed, particularly amongst established vegetation, can be rather hit and miss it pays to consider adding seed or plants over a period of years to build the success rate and diversity rather than rely on all species being established from a single application. This is perhaps even more important with smaller sites where it is easier to lose a species altogether from the site by the loss of a few individuals.
Create Gaps and Establishment Opportunities
Once seeds have found their way on to a site the young plants that result will need the space and time necessary to establish. It is important to provide this both when re-seeding a bare site and periodically over time as not all species are long-lived and will need to re-establish replacement plants from time to time.
For new sowings it is important to have a clean seed bed at the point of sowing to give all sown species the best start. When sowing a mixture it is also important to apply the seed at a low enough rate so that each seed has both space and time to get established without too much interference and competition from its neighbours. In practice this is quite tricky to arrange as some species will establish very quickly and others slowly: our recommendations for optimising this can be found as part of our mixture specifications.
For established sowings a managed degree of disturbance and gap creation is important to maintain diversity and continuity by allowing re-establishment of existing species as well as colonisation by new species. Each time a gap is produced the particular combination of gap size, season and weather conditions will be different, and as a result the plant species which are able to exploit each opportunity will be different. This diversity of opportunity helps develop and maintain plant species diversity over time.
Annual wild flowers require large gaps that result from extensive cultivation or disturbance. Many will not even germinate unless they have open ground.
Grassland species can establish in more modest gaps as created by hooves of grazing animals, by rabbits and moles, by deliberate or accidental manmade damage such as harrowing or vehicle damage and from die back of plants (yellow rattle in particular, being an annual, is useful in this regard).
In woodland establishment opportunities arise on a large scale from gaps when a tree falls or woodland is coppiced and on a smaller scale from disturbance or leaf litter accumulation.
Practical ways of maximising these opportunities are suggested within the notes on preparation and on management for each plant community type.
Restrict Species Dominance by Management
In theory if two or more plant species grow in close proximity in competition for the same basic resources of light, water and mineral nutrients in a stable environment, without disturbance or interference, eventually one species will emerge as the best adapted to the conditions. Species diversity will fall as a consequence leading ultimately to a community dominated by one species.
In the natural world there are no completely stable uniform environments and other influences such as animals, disease and humans periodically interrupt or prevent any one species attaining dominance. The tendency however exists to some extent in most situations and needs to be managed. The ability of plants to move in response to competition is limited so competition between plants is typically exerted in two main ways.
Firstly by expansive growth, increasing in size and spread, out growing and crowding out weaker neighbours, and secondly by deposition and accumulation of persistent leaf litter which suppresses establishment and growth of potential newcomers.
In practical terms to maximise diversity managed interventions are used which interrupt the successional processes of potentially dominant plants. The type and timing of these interventions will be aimed at having the maximum impact on the vigour of competitors and the most benefit to diversity. In grassland for example mowing or grazing to remove the expansive growth of competitive tussocky grasses or invading trees and scrub, and removing or preventing the accumulation of litter at the base of the sward, both help prevent loss of diversity and interest. These principles underpin the management guidance we have outlined for each habitat type.
Diversity of approaches
Diversity can also be encouraged through varied management approaches within each zone.
In grassland for example cutting date and frequency influences the balance and composition of the sward. So, rather than cut all of a meadow in one operation mow in sections at different times through the season, vary the cutting from year to year, and leave some areas uncut in some years.
It is always worth keeping in mind that the precise conditions and timings for optimal management in a particular site can be very hard to pin down and be prescriptive for. The ‘best’ approach will vary from site to site and will change with the weather and seasons. A varied approach and experimentation with management of your own site, together with observation and taking notes, is a very rewarding way of finding out and reviewing what works for your circumstances.
GREEN AND TURF ROOFS
Architects, planners, community groups and individuals are increasingly looking for new ways to green the urban environment, and with open space at a premium, roof-tops are seen as an under utilised resource to be developed.
Green roofs give their buildings a living, breathing skin that not only provides attractive greenery and an urban habitat, but also sound and heat insulation for a building, and can relieve pressure on drainage and water treatment works, absorbing and holding back rainfall and airborne pollutants.The green or living roof concept is now well established with many prestige and humble examples constructed in both the drier east and wetter western parts of the UK.
Many buildings have been transformed in this way, including large industrial complexes, schools and colleges, as well as more modest garden sheds, garages and temporary shipping containers. As these building schemes involve creating an environment from scratch they offer novel and interesting opportunities to create something a bit different as compared with landscaping open ground. Control of the type and depth of growing medium, the arrangement of irrigation and drainage, together with the slope and aspect of the roof mean that a wide range of choices exist as to the type of plants and species that can be grown. In general, roof schemes for wild flowers use a shallow depth of growing medium and are designed to develop ‘naturally’ with a minimum of maintenance. If you do not have a convenient roof to green but still want to try the technique you can achieve the same results by constructing a raised bed or sink garden.
Preparation and construction
Growing medium: Soils or Soil substitutes
A living roof for wild flowers will require a minimum depth of 80 – 150mm of growing medium. The ideal growing medium will be able to absorb and hold water, supply basic nutrients and maintain a fairly open structure for root growth. In addition, the material should not be too heavy or contain a high proportion of fine particles that can block filters. These requirements are not usually all found in one material so it is often best to use a blend of materials, preferably from locally sustainable sources. The advantages and disadvantages of the materials commonly employed are reviewed below.
NOTE: care should be taken when selecting the materials for your scheme as some may be deemed unsuitable for particular applications. Our plant based review that follows must not be taken as an endorsement of the suitability of any of the materials for roof construction projects – these issues should be addressed with your designer to make sure that environmental standards are met and manufacturers’ guarantees protected.
It is particularly important to remember that this depth of material will be very heavy, especially when wet. It can weigh up to four times the designed load bearing capacity of a tiled roof, so a structural assessment and some reinforcement is essential!
Lime based materials (chalk, concrete etc) are sometimes banned as they may compromise installed drainage and filter systems, and recycled green waste may have water quality issues in its run-off.
Crushed brick and concrete – for wild flowers some of the most interesting results can be achieved using recycled aggregates as a basis for a growing medium (‘soil’ forming substitute). These materials are generally low in nutrients and often lime rich which makes it possible to grow plants that cannot survive the competition of growth found on ordinary soils. Added to this, in urban situations these materials can usually be sourced locally and there is the satisfaction of physically transforming a piece of concrete jungle directly into green plant habitat!
Crushed brick – is probably the most generally useful of these soil forming recycled materials as it is porous and therefore lighter than other aggregates, can hold water and air within its pores and is often alkaline.
Crushed concrete – is useful as it is lime rich and nutrient poor in character so particularly suited for growing the specialist plants of chalk and limestone ‘scree’. Crushed concrete is, however, heavy and will not hold moisture. It is best used in combination with other materials.
Chalk or limestone chippings – where available locally are also excellent materials for plants – unlike concrete they can be quite good at holding water (especially softer chalks).
Sand and gravel based materials – can be used to create urban shingle or dune like communities. Fine sands should be avoided on exposed sites where the material may blow away, or block drainage.
Soil and subsoil – whilst soil is usually a good growing medium it is heavy, often carries a burden of weed seeds and roots, and may be too fertile, so should be chosen and used with care. Soil material with a significant clay or silt content is also best avoided as it can lead to drainage or soil-structural problems on roofs.
Composts/organic matter – raw soil forming materials like crushed aggregates or subsoil will usually need blending with organic matter to supply basic nutrients, hold moisture and reduce root restricting compaction. Well made green waste, domestic or peat-free composts are good but some can be too rich in nutrients so should be used in moderation. Wood fibre or recycled paper fibre are useful alternatives as they decompose and release nutrients very slowly.
Lightweight materials – such as manufactured water-retentive expanded rock granules are frequently incorporated into green roof designs to save weight.
Water retention, Drainage and Waterproofing
A constructed living roof will need to retain enough moisture to support plant growth but drain surplus water so that it does not become waterlogged. It will also need to have a waterproof layer to protect the building below.
Irrigation? -in drier eastern regions rainfall is not consistent enough in an average summer to prevent a shallow ‘soil’ drying out and the vegetation turning brown with die back. Irrigation is one possible solution especially if recycled water can be used. The better answer is to save water and accept the die back as part of the ecological cycle of your created habitat and select appropriate species that are either drought tolerant or are able to regenerate from seed (eg annuals/biennials). Open sparsely vegetated habitats created in this way are valuable for certain insects and spiders.
A living roof construction will usually contain the following components (from the bottom up):
- Waterproof and rootproof membrane(s) to prevent water and root penetration damaging the building
- Drainage layer – gravel (lightweight) or other material designed to drain excess water
- Filter sheet – geotextile or similar to allow water to drain but retain finer soil material
- Moisture blanket – to hold water (capillary matting or recycled carpet or textiles)
- ‘Soil’ / Substrate/ Growing medium
To create a diversity of micro habitats, the depth, composition and topography of the ‘soil’ may be varied. Surface features may include patches of coarse gravel or scattered stones (also help protect surface from heavy rain or wind blow), small boulders or logs.
Green roof sowing and aftercare
Seed of a suitable mixture (such as ER1 or ER1F) can be sown directly on to the prepared surface or sown in pots to be added as plants. Seed is best sown in the autumn unless irrigation is provided when seed can be sown in spring, summer or autumn.
Choice of species
When choosing species, raw soil forming materials like crushed concrete provide an ideal opportunity to select specialist plants which are adapted to periodic drought and nutrient stress but would not be able to compete when sown on typical topsoil.
Pioneer species known to be good at colonizing poor stony ground are good, as are species that can readily re-establish from seeds after drought. As initial establishment on poor materials can be slow, annual wild flowers can be added to also give flowers in the first season. Plants which are attractive or useful to insects add value to schemes. Tall species prone to wind damage are best avoided on exposed rooftops as are ‘weedy’ species with wind dispersed seeds that could cause problems by spreading to neighbouring properties. We have developed a seed mixture which is suitable for sowing on a wide range of substrates.
Grass or no grass?
Grasses are key components of many ecological systems and important food plants for a range of invertebrates. Many green roof designers however have a preference for mixtures based on wild flowers, with little or no grass component. These have been found to work well when sown onto poor, essentially sterile, substrates and avoid worries about competitive grasses taking over. However for many schemes it is still early days in terms of the progress of succession. Inevitably grasses will in time invade all sites. The decision to be taken at the design stage is whether to leave this to chance (accepting that ‘weed’ grasses are likely to be the first arrivals) or to pre-empt this by sowing a small quantity of short, attractive but non invasive grasses like Quaking grass and Crested hairgrass from the outset. The final choice of which grasses to include will be influenced by the nature, depth and history of the substrate. Poor, shallow, droughty materials may take a very long time to become grassy (if ever). Deeper topsoil based roofs in wetter regions will become grassy quite quickly so in these circumstances a turf roof approach is perhaps the more realistic or ecologically pragmatic solution and requires a suitable grass mixture with wild flowers and some aftercare (mowing).
To some extent green roofs have a historical precedent. In medieval and earlier times most roofs were covered with thatch or turf. Living turf roofs were the norm for low status dwellings and many thatched roofs were planted or turfed along their ridges. Modern construction methods have enabled a revival of this tradition without its failings. Grasses can be sown on roof schemes in most situations. On shallow ‘soils’ in regions with low rainfall, grasses will burn off in summer and cover will be sparse and open. In wetter regions or with irrigation a closed turf can develop which can be green all year round.
Aftercare of sown green and turf roofs
The requirement for aftercare will vary from scheme to scheme. Some will need minimal maintenance, perhaps only occasional tidying cuts for aesthetic reasons. Living roofs with reasonable growing conditions will produce growth that is likely to need annual maintenance for best results. This gardening will involve weeding and mowing along the lines of grassland aftercare. The practical and safety implications of maintenance work at height obviously need to be considered in advance of construction.
BEES, BUTTERFLIES AND OTHER WILDLIFE
Accompanying the loss of flower rich meadows, hedgerows and other valued habitat recorded over the last 50 years has been a decline in the insects, birds and other wildlife that depend upon them.
Naturalists are reporting reductions in numbers in a wide range of species. Notably this includes common species that we may take for granted like the skylark and house sparrow as well as rare and specialised animals that one might expect to find in a nature reserve.
Since Emorsgate first started promoting wild flower seed mixtures in 1980 many thousands of acres of new plant habitat have been created with the hope that at least some of the losses of plant habitat diversity can be offset. Whilst these newly created habitats cannot replace the value of ancient sites lost or damaged they have, over time, proven their worth as a new resource for wildlife.
Increasingly people are asking how they can maximise this potential and add value for specific types of insects, birds, reptiles or mammals. Specific advice is sought either as part of a local policy or BAP (Biodiversity Action Plan), targeting particular species or habitats in decline, or simply to develop or promote the interests of particular individuals or groups.
The guidance in this section seeks to highlight some of the things that can be done when creating habitat by sowing wild seeds.
In general terms, to be successful animal species need to be able to find the resources they require to complete their lifecycles. They need food and they need shelter.
Plants sit at the bottom of the food chain and so directly or indirectly provide food in the form of leaves or pollen and nectar.
Plants through the structure of the different vegetation types also offer shelter which may include nest sites in which to lay eggs or rear offspring and hibernation sites in which to overwinter.
For diversity of wildlife it is good therefore to have a diversity of plant species and also a diversity of vegetation structure. It is perhaps important to point out at this stage that all the elements an insect or bird species require to complete its life cycle will not always occur within one habitat. A flower rich meadow for example will be a rich source of pollen and nectar in summer, but after hay removal and through the winter is a poor refuge for many animals who may have to move to woods and scrub. In this way the location, arrangement and connectivity of a habitat is as important as the habitat type.
Our advice is firstly to sow and plant wild flowers and create plant communities for their own sake for their natural beauty and diversity. Research and our own experience over many years is that sowing wild seeds to create meadows and other new habitat does yield real benefits for insects and other wildlife. We believe that taking a holistic approach to sowing and managing botanically diverse habitats is the best way to provide the universal requirements for food and shelter for the widest variety of animals. The complex and often poorly understood requirements of the many species we may wish to encourage limit the rewards that can be expected from a more targeted species by species approach.
To thrive, bees need a continuous supply of suitable pollen and nectar from early spring, through summer and into autumn.
Bees will collect from a variety of species but do show strong preferences for legume species. When available, legumes (Birdsfoot Trefoil, Clovers and Vetches) can make up 60% of the pollen loads of bumblebees, and red clover in particular may account for 30%. Clover alone however will not supply a continuous or reliable source of pollen and nectar and other species are also very important.
Areas with a high density of suitable flowers are most attractive to bumblebees and flower rich meadow and grassland mixtures are the most dependable resource for foraging bees, offering both a quantity and diversity of pollen and nectar with plants such as selfheal, yellow rattle, knapweeds and scabious being particularly sought after. Cornfield Annual seed mixtures containing species like cornflower and corn marigold can also provide a very rich if only temporary source of pollen and nectar.
Bumble bees also require suitable places in long grass, banks or hedgerows in which they can nest. These sites are easy to provide and studies show that it is not lack of nest sites that limits the success of bumble bees but lack of pollen and nectar.
Butterflies and Moths
The life histories of butterflies and moths are complex, with caterpillars and adults having quite different food and habitat needs. Some species are quite mobile and as adults can easily move to find new habitat to meet their needs, other species are more sedentary/fixed and need to find all their requirements for nectar, larval food plants and over-wintering hibernation shelter within the same location.
Adult insects mainly feed on nectar and need habitats rich in flowers at the time of year they are in flight. Flower rich meadows and grassland offer a diversity of nectar sources which attract butterflies and moths. Nectar rich plants like Birdsfoot Trefoil, Knapweeds, Vetches and Clover are important, particularly for those species associated with grassland such as meadow brown, gatekeepers, skippers and common blue. Plants whose flowering period coincides with the flight period of particular species are particularly well visited. Later flowering field, small and Devilsbit Scabious are all very attractive to later broods of Tortoishells, Peacocks and Commas, as are wild marjoram on chalky soils and hemp agrimony and fleabane in wetlands.
Larval food plants
A key habitat requirement for all species will be the availability of suitable food plants for caterpillars. Grasses are larval food plants for a large number of butterfly and moth species. Some species like skippers and ringlets prefer tall coarser grass species, others like gatekeepers, meadow browns and marbled whites prefer fine grasses such as bents and fescues. Other food plants worth noting are Birdsfoot Trefoil for Common Blue, Garlic Mustard for Orange Tip and Green-veined White, and Common Sorrel for Small Copper. All these species are easily provided as common components of meadow seed mixtures, or hedgerow/woodland mixtures in the case of garlic mustard. In practice the contribution sowing these food plants makes to population sizes of a given species will vary. We have observed an increase in Common Blue butterflies wherever we have grown Birdsfoot Trefoil on our Norfolk farm. Common Blue butterflies are a relatively mobile species and its food plant, Birdsfoot Trefoil, was not common locally until we started growing it. In contrast there is probably rarely any benefit in planting or encouraging nettles as a food plant for small Tortoishells, Peacocks and Comma butterflies as it occurs so widely and abundantly in all environments that it is never in short supply. And finally we sadly cannot make any claims that if you sow milk parsley you will attract a breeding colony of Swallowtail butterflies!!
The vegetation structure and management (=disturbance) of a site is also important and requirements can vary from species to species. For meadow brown butterflies the ideal habitat is traditionally cropped hay meadow (hence their name) where eggs can be laid after the hay has been cut mid summer. The caterpillars emerge and feed on the young autumn re-growth until they hibernate as part grown caterpillars at the base of the sward. Gatekeepers need shrubs as well as grassland and can be found at the edges of grassland in woodland rides and hedgerows. Many species overwinter as caterpillars or pupae in the tussocky base of grass plants and will need some areas of rough undisturbed grassland to take refuge in. Continuously mown or grazed grassland is of limited use for many insects and even seasonal cutting of meadows can be quite disruptive for some species. In locations that are not over-managed there are usually rough corners and margins that if left undisturbed can provide a good refuge. In managed landscapes and gardens it is good to leave some grassland uncut through winter or perhaps sow a dedicated area with tall tussocky grasses (mix EM10).
Grasshoppers, beetles and others
Like bees and butterflies the basic habitat requirements of most other insect groups are for food and shelter. Some insect groups include species which are predatory or parasitic on other insects. The diversity of these species will reflect the diversity of host plant pollen and nectar feeders, and the diversity of these will in turn be affected by habitat and plant diversity. So once again by maximising the quantity and diversity of flowers for pollen and nectar, and plants for larvae and vegetation structure, the overall chances of attracting wildlife to your site are maximised.
Meadows and other areas of long grass are particularly valuable. You will notice the success of new areas of meadow grassland for grasshoppers and crickets when you hear for the first time their chorus on a summer day. The specific associations of plants with insects are too many and complex to mention, with many still to be discovered, but that is part of the interest in sowing a wide range of plants. Some plants seem to attract a diversity of bugs and other insects, such as hedge woundwort, others seem to have specific associations as figwort does with wasps for nectar. It has been shown that meadows and other diverse plant communities are important for hoverflies and predatory ground beetles which are important for pest control. These habitats undoubtedly also provide resources for pest species, but with a healthy functioning ecosystem both pest and predator are maintained and a balance is more assured.
Birds and Mammals
When planning a sowing with bird interest in mind the first thought is often to try and provide seeds for seed eating birds. Teasel, Knapweeds and Goatsbeard are certainly very attractive to Goldfinches when we grow them as seed crops! For other birds which eat seed it is often the larger grains of annual wild flowers, weeds and crops that are most attractive. A sown cornfield annual mixture with Cornflower, Corn Marigold and Forget-me-not can be good and these sowings often also allow space for other annual weeds like Groundsel, Fat Hen and Knotgrass.
For many birds, however, it is not the supply of seed that is important so much as the supply of insects and grubs to provide protein rich food for rearing young, even for those species which we may regard as seed eaters. In this regard it is the diversity and volume of plants and vegetation that determines the range and quantity of caterpillars available; and for this sowing meadows, rough grassland and enhancing hedgerows and woodland pays dividends. For owls, kestrels and other birds of prey, tall grasses and meadows also provide good hunting ground as they are excellent habitat for voles and other small mammals.
Habitat and vegetation structure can be important as with other wildlife. Lapwings and Skylarks for example need some open space in short grazed or mown turf for ground nesting; other birds such as Tree Sparrows need dense cover for nesting as provided by hedges, woodland and scrub.
Small mammals and other animals
The basic requirements for all animals are food and shelter. Grassland that is managed by mowing and grazing as meadows or pasture is best at providing a diversity of fresh nutritious herbage, whereas undisturbed infrequently managed areas provide the best shelter. Sites which provide a mosaic of both in space or over time offer the best overall potential for wildlife, and this is usually achieved through management and the timing and frequency of this management. Water voles, for example, benefit from a management plan in which waterside banks are only cut and cleared in short sections at any one time to provide patches of fresh vegetation near the waterline alongside areas of uncut rough cover for shelter. For many species it is the overall diversity of both plant species and the insects they support that yields benefits. A meadow that supports a wide variety of moths for example makes excellent night hunting for bats.
Footnote: Clovers in seed mixtures
Red and white clover are natural components of many ancient meadows and grasslands. However simply adding clover to a wild flower seed mixture (especially cultivated forms) is not generally recommended, as their vigour and ability to fix nitrogen tends to push the sward to a more fertile grassy condition, creating management difficulties and a loss of overall diversity. Clovers (especially red clover) are also very prone to ‘boom bust’ cycles from year to year. Cultivated red clover will typically dominate the sward in the first two years, and then disappear completely in year three giving bee populations no long term stability. Within farmland environmental schemes ‘pollen and nectar’ mixtures based on clover are a popular and cheap way of providing a short term abundance of nectar. They are of some use if re-sown every 2-4 years and planned with other more diverse long term wild flower rich habitats to provide continuity. Clovers sown in other contexts (eg sown with lawn or grazing mixtures) can be of some benefit to foraging insects.
Biodiversity is all around us, in towns and gardens as well as in the countryside. We all have a part to play to protect biodiversity and the integrity of our environment.
Individuals in their lifestyle choices and practically in their gardens can make a real contribution. Businesses and public organisations now have a duty of care to consider biodiversity as part of sustainable social and economic development.
One simple and practical way in which both individuals and organisations can promote biodiversity is to sow wild seed.
The UK Biodiversity Action Plan (UK BAP) is the government co-ordinated response to protect a designated list of priority species and habitats. It includes over 1000 species and 65 habitats. Local authorities and wildlife groups implement these BAP plans regionally and include practical objectives and targets.
Wild flower seed mixtures have already demonstrated their value for enhancing and restoring biodiversity in a number of key BAP priority habitats:
Upland Hay Meadows
Lowland Calcareous Grassland
Upland Calcareous Grassland
Arable Field Margins
Wood-Pasture & Parkland
Lowland Mixed Deciduous Woodland
Sowing seed and good management can enhance the biodiversity of individual sites. When many schemes link up they combine to create a resource of greater value than the sum of its parts. Meadows and wildlife areas created in gardens can, for example, be linked by road verges landscaped with wild flowers to similarly enriched field margins around farm crops. This network of connected habitats, once established, will become an invaluable resource boosting, amongst other things, the number and diversity of pollinating insects upon which our food crops depend.
What is biodiversity?
Biodiversity is a term used to describe the variety of life on earth. The concept of Biodiversity (as agreed by international convention) encompasses diversity of all plant, animal, fungi and microbial species as well as the genetic diversity that exists within these species on a local level. Biodiversity also includes the many and varied associations of these organisms in ecological complexes and ecosystems.
Why does biodiversity matter?
Biodiversity is not important just because of the direct benefits that can be obtained from individual species. Biodiversity is important because all life, including human life, is intricately interdependent on all other life; the loss of any part of the network of life can produce knock on effects through the whole life-support system. Systems that are rich in species and genetic diversity are generally more resilient and more able to adapt to change whether locally or globally, natural or man-made (as with climate change).
With the right training in scythe use and sharpening a good scythe is a surprisingly economical and efficient tool for mowing small to modest areas of grassland.
Good grassland management is absolutely fundamental to maintaining flower rich biodiverse meadows and grassland. In practice implementing the best mowing regime at the right time of year can be quite a challenge. This is particularly true of small to moderate sized areas of grassland in inaccessible locations. If you are able to find an operator with suitable machinery and persuade them to mow your grassland you often have to compromise as to when the area is cut and have the job done in one hit.
The main advantages of scythe use for grassland management are:
- Better control over when to cut.
- Easier to spread mowing over time to create habitat diversity rather than cut all at once
- Ability mow selectively
- Less disruptive to wildlife than machinery
There are many additional benefits which you will discover if you adopt scything.
Situations where scythes win over machines:
- Where machines and their noise would cause disturbance to locals or wild life
- Where sites are unsuitable for machines; either too small or inaccessible
- For individuals and volunteer groups who want to work together as a team without the noise or health and safety issues associated with powered machinery.
By staggering mowing and hay making over the season an individual novice should be able to manage up to 1/2 acre (2000m2) of meadow with a scythe, experienced mowers and groups can tackle larger areas.
A competent mower can cut a meadow in less time than it takes to clear cut grass or make hay. Depending on weather, and how often you need to turn the hay, you will need to allow 2 -5 people per mower (or equivalent man hours) for turning, gathering, carting and stacking hay. Another reason for staggering the mowing schedule is to spread the workload: don’t mow more in one day than you can handle. Even if you do not wish to save the hay for fodder it is good to at least partially dry the hay on the meadow before carting. This allows seeds to drop back and massively reduces the weight and volume of material to be carted off (as over 80% of the weight in fresh cut grass is water). Always clear cut material from grassland otherwise its structure and diversity will suffer. Scythe cut grass is nicer to handle than the mashed grass left by many mechanical mowers.
Scythes can be used for a wide variety of habitat management tasks
- Mowing meadows and grassland
- Controlling bracken
- Cutting wetland and reedbeds
- Mowing weeds
- Woodland under-storey management
Choosing the right scythe
A scythe is a surprisingly ergonomic tool to use provided it is of the correct size with proportions matched to the user. Old second hand ‘English’ scythes are rarely configured to suit a modern user. Modern ‘Austrian’ scythes are usually a better option as they are a lighter and more refined tool.
Acquiring the necessary skills
To use a scythe efficiently and safely you will also need to acquire basic mowing skills. The best way to learn mowing and sharpening techniques is by instruction. There are now a number of scythe instructors around the country offering courses, including some at Emorsgate here in East Anglia with Richard Brown at Wild Scythe.
A one day introductory course should teach you enough to be able to return home and get your grass cut. Efficient mowing however will take time and practice to develop; this is where further guidance and instruction from experienced mowers can be helpful. The scythe association organises a number of meetings and festivals though the year where you can get free advice and guidance. There is also quite a lot of useful information available online and in print to refer to.
Stay sharp. Mowing with anything less than a keenly sharpened blade is both difficult and hard work. New scythes come with a factory sharpened blade which will cut straight out of the packet, but after just 5 – 10 minutes mowing it will have lost some of its edge and need re-honing. Blade sharpening skills are essential to learn from the outset. The first essential technique is honing; sharpening the edge of the blade with a whetstone. In the field you typically hone every 5-10 minutes whilst mowing. After about 4 – 8 hours mowing and honing the blade will benefit from peening (hammering to maintain and reshape the bevelled edge). Peening is usually done back at base between sessions. Peening is another skill that takes practice to get best results. A chainsaw file is a reasonable, if inferior, substitute where peening is not practical.
Learn from the scythe
Mowing a meadow with a scythe provides a much more intense sensory engagement with the grassland than is ever possible with a machine. You will learn far more about its character, composition and structure and how this varies across your site. You will discover over time the effect of different management regimes has, how more frequently mown grassland encourages fine grass and herbs whilst infrequent late mowing favours coarse vegetation. Even on large site which is cut by machine it is worth mowing sections with a scythe just to gain a better feel and understanding of the plant community growing there.
Use of the scythe will teach you the importance of mowing meadows at the right time. You will soon discover areas which have been neglected or left too long (“over-stood”), areas which have become hard to mow because the vegetation has now collapsed, become entangled and rotting at the base. This neglect compromises flowering plant diversity, but also makes mowing difficult.
Rough tussocky grassland that has been left uncut deliberately as a shelter for insects and small mammals can be tackled when needed with a scythe, pick the best time for your site and accept that work rates will be slower.