University of Illinois Extension

Fall Vegetable Gardening

As retail prices for fresh vegetables rise in the fall, many homeowners would like to be harvesting their own until the first freeze arrives, says a University of Illinois Extension horticulturist, Maurice Ogutu.

“There are many challenges they need to overcome in order to do this,” explained Ogutu, “such as a short growing season, cool weather in the fall, and sensitivity of warm season vegetables to freezing temperatures.

“Some gardeners can extend the harvesting season until the first frost by practicing succession planting of warm-season vegetables such as cucumbers, summer squash, green beans, and sweet corn.  Cool-season vegetables such as spinach, kale, Brussels sprouts, and others can grow during fall’s cool days and can tolerate light frost.”

Planting time is very critical for fall vegetable gardening as there is a short growing period when it is warm enough for the vegetables to grow. It is very important to know the average date when the first killing frost is expected in your area and the days from planting seeds or transplanting seedlings to maturity for vegetable varieties you wish to grow.

“You also need to consider that it tends to be cooler in the fall so plant growth is slower. You need to put a factor of two weeks to account for that,” he said. “If you are growing tender or warm-loving types of vegetables such as cucumber, green beans, and summer squash, you need to plant them so that they mature two weeks before the first frost.

“How long you intend to harvest the crop also needs to be considered. Add all these days and start counting back from the first frost date to determine when to plant the vegetables. The warm-loving vegetables for fall gardens can be planted in late summer, much earlier than the cool-season vegetables. Due to the short growing period in summer, try to use transplants as they take less time to mature compared to vegetables started from seeds.”

If vegetables are to be grown on a site where other plants were grown during the spring or summer, the soil needs to be prepared, weeds controlled, and compost or fertilizer added.

“There are some pests that can be a problem in fall gardens such as imported cabbage worm, cabbage looper, and diamondback moth in Cole crops such as cabbages, cauliflowers and broccoli,” Ogutu said. “Fruit worms can be a problem in tomato and peppers. You should practice crop rotation by growing vegetables from different families on one site to reduce build-up of insect pests and soil-borne diseases.

“Plant vegetables after rain or irrigate immediately after planting or transplanting if the soil is dry. After germination or transplanting, you can cover soil both around the base of the plant and between the rows with a layer of organic mulch such as straw to retain moisture and control weeds.”

Plants should be given one-inch of water per week if rainfall of more than one-inch a week is recorded in your area. During extended dry periods, water the plants by thoroughly soaking the soil up to six inches in depth.

When the arrival of the first frost is predicted, harvest the ripe crops that are very sensitive to frost such as tomato, summer squash, watermelons, muskmelons, cucumber, pumpkin, eggplant, and peppers. Tender vegetables can be protected with plastic sheets, blankets, and other items so that immature fruits can develop during warm days to maturity if the freezing is mild--about 30 degrees F.

“Cool season vegetables such as cauliflowers, cabbages, Brussels sprouts, spinach, collards, and Swiss chard can withstand some cold temperatures and can stay in the garden after the first frost,” said Ogutu. “Other cool season vegetables such as carrots, parsnips, kale, spinach, bunching onions, lettuce, and parsley may stay longer and need to be mulched by four to six-inch thick straw. These can be dug--if root crops--and used in the winter before snow covers the ground.”

Perennial vegetables such as asparagus and rhubarb need to be prepared for winter.

“You can top-dress them with compost or well-rotted manure and cover them with mulch,” he said.