Late winter and unseasonal snow has left many garden soils cold and inhospitable.
Spring is the time for new root growth and annual plants and vegetables need the best start possible.
Vegetables and ornamental plants need a bit of warmth to get established and growing away.
Clay soils is traditionally slow to warm through as they hold a bulk of water.
Warming Your Soil
I use several methods to warm the soil and control the amount of water.
A cloche will cover an unsown area until you are ready to plant. It will slow down heat loss at night, speeds germination and also offers protection to young plants – I have started off my onion sets under a plastic tunnel type of cloche this month.
Black absorbs the suns heat and white tends to reflect heat. You can lay black plastic on an area of soil to get some warmth but ensure a good contact between the two. Hoe off any weeds before planting out.
Horticultural fleece is best for protecting young crops from late frost and will only do a little to warm the soil.
Compacted soil is inhospitable and likely to be cold. Incorporate plenty of humus and dig over to get air into the soil.
More Tips for a Cold Soil
- Dry soil warms up quicker than wet soil. Good drainage helps a wet soil and organic matter helps darken the soil that improved heat retention
- Sheltering from cold winds and evaporation will help improve soil temperature.
- Do not rush, late sowing and planting will generally catch up. Better to wait than risk a crop failure.
- It is easier to warm soil on a window ledge, in a greenhouse or poly-tunnel to get a quick start.
- Frost and cold air runs down hill – it may seem contrary but the top of a soil pile may be warmer than the bottom.
- Choose crops that are suitable for colder regions.
- Old gardens used raised beds of semi rotted manure to warm soil for courgettes and even pineapples.
Summary Tips & Techniques
- Keep frost out by covering.
- Shelter from stiff winds
- Sun will heat darker soil quicker
- Think conservatory and heated greenhouse for those delicate plants
- Use under-soil heaters for good germination