A fall garden can not only extend your vegetable harvest season, but it can also allow for better-quality crops when growing certain vegetables that enjoy cooler weather as they mature. Fall vegetables include broccoli, Brussels sprouts, cabbages, fava beans, cauliflower, carrots, parsnips, beets, rutabagas and globe onions, as well as spinach and lettuces. The best planting time for a fall garden is in July or August. Depending on your region's climate, the planting date may be later or earlier to allow the fall vegetables to mature and harvest to occur before the first hard, killing frost.
Remove any summer crop remnants left in your garden, as well as any weeds or grasses. Loosen the soil to a depth of at least 8 inches, using a pitchfork or rototiller.
Mix into the garden soil a granular 10-10-10 NPK (nitrogen-phosphorus-potassium) fertilizer at a rate of 1 to 2 lbs. per 100 square feet. If you fertilized your summer garden heavily, you don't need to add this fertilizer to the soil before planting.
Dig 4-inch-deep furrows into the soil, spaced about 1 foot apart. Plant the fall vegetable seeds 1½ to 2 times deeper than the instructions on the seed package recommend for spring planting. Spread potting soil or vermiculite over the seeds.
Water your fall vegetable seeds daily to keep the soil thoroughly moistened at all times until germination. After the seeds germinate, water the fall vegetable seedlings deeply once or twice each week to supplement rainfall and provide about 1 inch of water per week.
Spread 1 inch of aged manure or a side-dress application of a high-nitrogen fertilizer after the fall vegetables begin to grow, at three weeks and again at six weeks.