As the kitchen garden soil has worked hard to produce crops through the season you should try to repair some of the wear and tear during the autumn and winter. One of the best ways is to sow a green manure crop. It acts as a living mulch, preventing the soil’s valuable nutrients from draining away with the winter rain. Come spring the crop is cut, laid on the soil surface and then immediately dug into the top few inches of the soil, adding valuable organic matter and acting as further plant food as it breaks down.
Green manure crops do not have to grow on their own through the winter — one of the best crops of purple sprouting broccoli I ever grew spent the winter nestled among a thick bed of red clover. The following spring, when the spent broccoli plants were removed, the clover was cut and then dug in.
Here is a selection of green manure crops, all of which can be sown now.
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Red clover
This is my favourite because it is a legume and so fixes free atmospheric nitrogen. It also produces an array of brilliant red flowers in early spring. These attract insects which help to pollinate early- flowering plants such as pears. Broadcast the seed over the soil surface as if you were sowing grass seed and then rake over gently. After a slow start in the autumn, growth will halt through the winter. In spring the clover will reach up to 12in (30cm) in height. I usually wait until the flowers start to go over before cutting the crop down, but you can do it before flowering. Leave the cut crop on the soil surface for a few days to allow it to wilt and then dig it in.
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Phacelia tanacetifolia
The handsome blue flowers attract myriad insect life. It reaches a good size, like clover, and should be cultivated and cut in the same way.
Hungarian grazing rye
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This is a grass that germinates well in autumn and stands well over winter. It grows to 5-6in high. Sow as for clover and dig into the soil without cutting in spring.
Field beans
These are smaller than broad beans and grown by farmers for animal fodder. Like clover, they fix nitrogen. They germinate well until November. Sow as for broad beans, pushing the beans down into the soil, 1in deep and 4in apart. They will grow well over the winter and are easy to chop up and dig in.
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Suppliers
Tamar Organics (01822 834887; www.tamarorganics.co.uk)
Organic Gardening Catalogue (0845 1301304; www.OrganicCatalog.com)
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Tom Petherick
Join Tom Petherick at Petersham Nurseries, Petersham, Surrey, on September 27 for a lecture and workshop on growing vegetables and a tour of Petersham House garden. Tickets £120 (includes lunch cooked by Skye Gyngell). Call 020-8940 5230 or visit www.petershamnurseries.com