There are three ways to improve clay soil:

• Improve drainage for crops like garlic by planting into ridges made above soil level. This is great for winter crops and early plantings because the roots are raised out of the coldest, soggiest part of the soil.
• Cover a cold, wet, heavy soil early in the year with polythene to dry it prior to planting and sowing. Fix piping over beds in hoops to raise the polythene off the soil to allow air in to dry and warm it.
• Spread 5cm (2in) of gritty sand or fine shingle over the surface and fork it in, or spread grit, then a thick organic mulch on top and let the worms mix it in for you.

Jobs to do this week are:

• Plant early, second early and maincrop potatoes.
• Prepare trenches for celery and runner beans by manuring a strip of ground for each.
• Start dahlia tubers into growth in a warm greenhouse and take cuttings from those already producing shoots.
• Repot houseplants and give them a week or two in the greenhouse to convalesce.
• Plant out autumn-sown sweet peas.
• Protect emerging hostas and other susceptible plants from slugs and snails.
• Thin out autumn-sown annuals.
• Firm in newly-planted fruit trees and bushes after frost.
• Sow herbs in a cold frame.
• Plant out cabbages raised under glass in January.
• Continue to spike and scarify your lawn to improve drainage and remove thatch.

By Martin Ford