With the main growing season on the wane, it's time to start thinking about putting the vegetable garden to bed for the winter. The idle period between summer and spring also can be immensely important to the long-term viability of a vegetable garden.
One of the single most important things a vegetable gardener can do in the fall is to till compost or vegetable matter into the soil. Particularly in parts of northeast Kansas where we garden on top of clay or limestone, our best bet for having a productive garden is to routinely amend the soil. Soil that has been supplemented with organic matter has greater tilth, retains moisture and nutrients better, and contains microbes that energize the soil.
The rule of thumb for soil amendment is to till in one inch of organic material for the surface area of the garden each year to maintain soil quality. For a large garden, that sounds like a lot of organic material. But this need not be a major project if you do it at the end of the gardening season.
Significant sources of soil amendments are already in the garden. For starters, as crops finish production, go ahead and till the plants into the soil. Run the lawn mower over sturdier plants to break them down before you till them under. This will speed up decomposition. Avoid tilling under any plants that are showing signs of disease. Remove them from the garden and don't compost them.
You also can till in the organic mulches you applied during the growing season. If you used straw, leaves, grass clippings or some other biodegradable material, turn it under. People who mulch heavily and till it all under at the end of the season generally have wonderful soil. By spring, when you till again for next year's garden, these materials will have decomposed into humus.
If you have a supply of finished compost, it also can be tilled into the soil now or in the spring. One effective method is to create furrows or small trenches parallel to one another and fill them with the finished compost. Then till over the top, perpendicular to the furrows so you cut across the lines of compost and spread it as you till.
If your soil needs serious help, late summer and early fall also are your last opportunities to sow a green manure crop. Clover, hairy vetch, buckwheat and winter rye are good choices for end-of-the-season cover crops. All of them fix nitrogen or phosphorous into the soil and improve soil tilth. They also prevent the soil erosion and loss of soil nutrients that happen in a bare garden.
Garden supply and farm stores sell the seed for green manure crops. The trick to getting these crops established now will be keeping the soil and seed moist enough for germination. Without rain, you'll need to water.
In very early spring, the green manure crops should be tilled under, and you'll probably have to mow them first. Hairy vetch, in particular, can tangle up a tiller and must be cut down before you till.