When to start spring sowing?

March the 1st is the first day of meteorological spring!

With the arrival of spring (and hopefully some spring-like weather) we are often asked the question "how soon can we begin sowing wild flower seeds?"

This year there were record day time temperatures late February, and the first time a temperature of over 20C has been recorded in winter! I grabbed the opportunity to re-sow cornfield annuals in my own garden, and to a sow a newly constructed green roof. Whilst these warm days were followed by some cold nights with frosts, and there remains a chance of a cold spell in March or April as in 2018, wild seeds are generally hardy enough to sit these out and will not come to harm.

Green roof sowing

Seed divided in two parts ready for sowing on chalky subsoil roof substrate

Seeds need a combination of both warmth and moist soil (but not waterlogged ground) in which to germinate and grow.   These conditions are most often met sometime during March and April but the exact timing will vary depending on soil type, location, and the patterns of weather that particular season.

How early you can start sowing will depend on character of your soil.

Light free draining soils warm up and dry more quickly are often ready from early March.  Where a soil is prone to drought later in summer, as for example on shallow green roof substrates, then early sowings can prove more reliable.

Cold wet clay soils are often difficult to cultivate to create a seedbed in early spring, and may not be dry enough or warm up enough to sow until April.

If you have ground preparation to do before sowing then you do need to allow enough time for this. If the soil is wet and unworkable you will need to delay until soil conditions improve to complete this and produce a good seed bed.

Where you can prepare a good seedbed in early spring sowing wild flower seed is a safe option in most years. Wild flowers are quite hardy, and should the weather turn cold for a spell the sowing will not come to any harm. Their seed is quite resilient; it can last for weeks or months in the soil and germinate at the next opportunity when conditions improve.  Many wild species are actually ‘primed' to germinate if exposed to a spell of cold weather after sowing then germinate more freely when the soil warms than seed sown directly into a warm seedbed.

Green roof seed mix

Mixing seed with larger volume of sawdust to aid spreading by hand

Posted on 01 March 2019,
Category: News