After removing spent tomato plants and other summer crops, rake out each bed, then carpet it with 2-3 inches of composted dairy manure or mature compost. If you aren’t using the space for fall vegetables, consider planting a cover crop of nitrogen-fixing fava beans or winter field peas to preserve soil quality. These fast growing annual crops reduce soil loss from wild winter winds and protect it from washing away in heavy rains, which also leach out nitrogen and other nutrients. Sow your cover crop after spreading mulch, since both aged manure and mature compost absorb water, reducing runoff and nutrient loss.
Cover crops are sometimes called “green manures” for their soil-building properties. Hand-sow your seed in late summer or early autumn (now is a fine time), lightly raking it in to prevent it from becoming expensive bird food. When the plants reach about 18 inches in height, chop them back by half. This may happen 2-3 times in a warm year, or just once in a tough one.
Together, the mulch and the cover crop leave little opportunity for weeds, which sprout eagerly during our mild winters. Don’t mow down cover crops until mid February or early March. If it’s too wet to mow, just weed-whack each bed. The decaying top growth enriches soil nutrient quality while the rotting roots restore soil texture. There is no need to till (which destroys soil texture); if cover crops don’t “melt” quickly, simply dig them in a little and plant right around them.