Add the frosty nights of late February to soil that’s still sodden after the winter rain and it may not be until the middle of the month that the soil in your vegetable garden is warm enough to sow early crops. However, this should not stop you from preparing the seedbed, by raking the ground to a rough level and covering it with clear or black polythene to warm the soil. Clear polythene is preferable, as it encourages weed seeds to germinate which can be hoed off beforehand, so they don’t compete with your germinating crops. Most seeds take longer to germinate in lower temperatures.
Peas and parsnips take four weeks or more to appear if sown in early spring but only ten days if temperatures are higher. Turnips, radishes, broad beans and peas germinate when the soil temperature is above 41F (5C), Leeks and onions need a minimum temperature of 45F(7C) (it’s also the minimum temperature for potatoes to grow) and lettuce germinates well when it’s cool but not when soil temperatures are above 77F (25C).
A soil thermometer takes the risk out of sowing. Beetroot, broad bean, carrot, kohl rabi, leeks, lettuce, pea, radish, salad leaves, spinach, Swiss chard and turnip can be your earliest sowings – be guided by the weather. Choose ‘bolting’ resistant varieties to reduce the risk of early sowings running to seed prematurely, then cover the ground with cloches or horticultural fleece to protect emerging seedlings from pests and diseases and the effects of chilling winds. Make extra sowings in modules or plugs indoors or on a sunny windowsill as a back-up.
Aubergines, that need a long growing season can be sown now in a heated greenhouse or propagator. Buy fresh seed compost at the beginning of each season, turning the bag ‘end over end’ to ensure that it is well mixed and keep it in the greenhouse to warm up for several days before use. Alternatively, fill and water several seed trays of compost then put them in to propagator to warm for twenty-four hours, before sowing.
Early to mid-March signals the end of the planting season for field grown ‘bare root’ stock like trees, hedging, roses; search websites now for a bargain. Plant ‘woody’ plants immediately, before they burst into growth and don’t plant if the soil is waterlogged or frozen.
Once winter flowering jasmine has finished blooming, cut out weak or damaged shoots or those that have flowered, to a strong stem, tie in the remaining stems to the supporting framework and cut side shoots back to a bud at 5cm(2”) from the main stem. Feed with slow release general fertiliser then mulch and water to ensure plenty of regrowth for an abundance of flowers next winter.
Keeping early infestations of pests like aphids under control, certainly saves you problems later in the year; protect young soft growth of herbaceous plants from slugs using barriers and slug traps. Wrap up warmly and get gardening; there’s plenty to do.
Happy Gardening! Matt