Gardeners who want to get the most from their gardens can extend the growing season by planting cold-tolerant vegetables in the fall. Many vegetables that are planted in the fall continue to grow into the late winter, and may be harvested almost up to spring.
Onions and garlic are both members of the Allium family. Onion plants are best when sown in August and harvested before the ground experiences a hard freeze. Onions prefer rich soil, but can grow in sandy soil or loam that has been amended with organic soil. Onions can be harvested while young and tender, or they can be lifted after they are mature, dried and stored for long-term use.
Stiffneck garlic can be planted in the fall and harvested the following summer. Garlic makes a good companion plant to your summer vegetables because it repels many insects that feed on vegetables. You can leave the garlic bulbs in the ground for several seasons and use garlic flowers in cooking as well.
Broccoli is a member of the cabbage family and is closely related to cauliflower. Like many members of the cabbage family, broccoli thrives in cool weather and is frost tolerant. Grow broccoli when temperatures fall below 70 degrees Fahrenheit. If the plant is subjected to temperatures warmer than 70, the crowns may become slimy. Plant seeds in full sun one-quarter to one-half inch deep. Thin the sprouts so that they are 18 inches apart.
Cabbage also is a cold tolerant vegetable that grows into a ball of densely-packed leaves. Cabbage may grow in shades of green, red and purple. Varieties of cabbage grow throughout the world, and the vegetable is incorporated into dishes from many cultures. Plant cabbage one-quarter to one-half inch deep in midsummer for harvesting in the fall. Harvest before the cabbage heads can split open. The seeds germinate well when the soil is approximately 70 to 80 degrees Fahrenheit. Thin seedlings to 18 inches apart.
Root crops such as radishes, carrots, turnips, and parsnips grow well in the fall and winter months. Radishes are fast-growing plants that will thrive in small spaces, provided there is sun and fertile soil. Sow winter radishes in late summer for a slow-growing plant with large, crisp root crops that store for longer periods of time. Because winter varieties have larger roots, they should be thinned so that there is at least 4 inches of space between the plants.
Parsnips are best harvested in winter because their sweet flavor does not develop until the plant has been exposed to frost. Sow parsnip seeds thickly, because the seeds do not germinate well, and be sure the soil is deep and loose to encourage larger roots. Thin plants to 4 inches apart.
Carrots started in the early fall can be harvested just before the first frost.
Greens such as spinach, chard, arugla and kale grow well in cool weather. The growing season for these leafy vegetables can even be extended with the use of a cold frame or floating row covers. Sow these leafy vegetables in August and September for salad greens within two weeks and mature plants for cooking in 40 days. Choose a sunny spot with at least 6 hours of sunlight to grow those plants. Place the seeds in the ground and cover with one-half inch of soil. Thin the plants when they sprout.