Cover crops are the best way to replenish the soil in your garden. Fall cover crops will keep that soil alive through the winter. There are several seed types that are ideal for this, which ones really depend on the type of soil you have, and what your climate or hardiness zone is.
Generally, it's best to clear out your summer garden about four weeks before the first frost date. Healthy plants can be cut down or pulled out by the roots and added to your compost pile. Any diseased plants should not be composted, for the safety of the garden soil and future harvests. For those, it's best to pull them out by the roots, and carefully dispose of them, in a plastic trash bag.
Then comes the fun part! Add some compost to your garden and plant some cover crops. Some of the best of these are legumes, grains, or radishes. A personal favorite, and an easy grower in the fall that's great for raised beds, is the legume Hairy Vetch.
The cover crops will add nitrogen back to the soil, suppress weeds, and some will break up the ground. Remove them in spring, before they flower. An easy way to do that is to use a weed-wacker and crop them completely down. Leave the plants scattered on the surface to dry out for a few days, then turn it over into the garden. This will add good organic material to the soil, as they break down over a few weeks.
Written by David Wiley