Most of the best vegetables for fall gardening are either root crops or cruciferous vegetables. The key to successful planting is knowing the average date of the first killing frost and planting a crop enough in advance of that date to allow it to reach full maturity before that deadline.
Local county extension offices are usually the best sources of information about frost dates in a given area. Extension agents also provide advice on the crops best suited to the area and offer soil testing services.
The first plants to plant for a fall garden include beets, globe onions, carrots, cabbages and Brussel sprouts. Parsnips, rutabagas, cauliflower and fava beans are also options. All these plants need about 90 days to mature. Carrots and parsnips can stay in the ground after maturity, and parsnips usually taste better after at least one heavy frost.
The second group for fall planting includes early varieties of carrots and cabbages, leeks, collards, turnips, and Swiss chard. These plants need about 60 days to mature. Perennial herbs and flowers are also good choices for planting at this time.
The quickest-maturing fall vegetables only need about 30 days to yield a crop. They include broccoli, chives, bunching onions, spinach and leaf lettuces. Thirty days before the first heavy frost is the time to plant cover crops intended for green manure.