Preparing potatoes for planting

which seems a bit optimistic but I’ll give it a go. I’ve given up on ‘‘earthing up’’ because it’s so fiddly in pots and it’s easy to break the shoots. I cover the pot drainage holes with a piece of weed mat to stop the soil washing out. Then I place the seed potatoes on a layer of potting mix around 5cm deep and fill each container to 5cm below the rim to allow for watering.

Leafy sprouts show at the surface surprisingly quickly. I add potato fertiliser as I’m usually reusing potting mix that has already grown a previous crop. general, the soil in wooden raised beds is warmer than garden beds, and metal and terracotta pots are warmer still. For example, one afternoon, when the air temperature was 15°C; the soil in a wooden raised bed was 12°C; the soil in an old copper in full sun was 13°C, but heavy, waterlogged clay garden soil only reached 10°C.

Moisture and soil consistency affect the temperature too. Light, aerated potting mix that’s well drained warms up much faster than dense, waterlogged clay. Interestingly, the soil temperature is much more stable than the air temperature. Early the following morning, the air temperature was 11°C, the raised bed and the copper were 12°C and the clay soil was still at 10°C.So why does it matter? Seeds need specific temperatures for germination.

You’ll have much better results if you wait until the temperature is in the right range before sowing spring and summer crops. Beans, for example, need soil temperatures of 18-25°C for reliable germination. There are some soil warming techniques to speed things up. Try covering a garden bed with a cloche or a sheet of plastic to warm up the soil for a couple of weeks before planting. I’m using the polycarbonate sheets to warm up my soggiest garden bed.