Don't leave bare patches of soil lying idle over winter, especially in the vegetable garden, an area that should be treated with care and respect. Instead, plant a cover crop of green manure to protect the soil structure, to smother weeds, to add nutrients and to keep the soil active and healthy. Good garden centres stock various green manures. Some that you can sow over the next week or two include winter field beans, winter tares, mustard, Phacelia and Hungarian grazing rye.
Green manures should be dug back into the soil in spring before their growth has hardened: lush, green leaves decompose faster than woody stems. Alternatively, you can pull up the crop and compost it. Leave the roots of leguminous green manures (beans and tares) in the soil, as they assist in nitrogen production. After harvesting or digging in a green manure, don't plant a new crop for a couple of weeks. Give the soil time to break down the organic matter you've just added.