Prep soil for tender veg
We may obsess about the weather, but is our soil warm enough? Bob explains how to warm sites for tender crops
SO what connects the following: tomatoes, marrows, courgettes, squashes, pumpkins, ridge cucumbers, runner beans, French beans, soya beans and sweet potatoes? Well, of course, these are all tender crops. They cannot take any frost – one touch, and they’re lost. Even in the warmest of gardens, these should not be planted out for another fortnight or so, unless given extra protection.
And then it also takes a favourable summer to get the best, as they really need warmth. That’s warmth all over, not just to their tops! You see, we’re too keen to get them planted out but we’re watching weather conditions, not soil temperature. Planting out into too cold a soil may stall or check the plants, which do poorly for the rest of the season.
Better to wait another week or two, potting up as necessary, and plant out into warmer soil when the plants will then just romp away. It also makes a huge difference to how soon you can plant successfully if you add protection with a cloche, clear plastic sheet or even fleece. But these only help once put in place.
So the best practice is for you to position your cloches, plastic sheets or whatever in place now. Then they will be prewarming the soil into which you will be planting. You can also help by coating that soil surface with a fine dusting of powdered charcoal; the dark colour absorbs the sunlight, heating the soil that is then kept warm by the cloche or whatever. (Soot was traditional, but is now considered potentially hazardous.) Likewise, you can raise your soil temperature by laying a black plastic sheet or geotextile to absorb the heat from the sun, which is then trapped by the cloches or clear plastic. So all will then be snug and warm, ready for your plants!
“Soil temperature is key to success!”