Extension Educator, Horticulture
You can't harvest a "meant to". Many a gardener has confessed "I meant to get that planted". Our good intentions started with the insatiable lure of voluptuous vegetables. We bought the seeds and then life happened. We just never got around to getting them in the ground in spring.
Good news is a fall vegetable garden offers some advantages over a spring garden. It can be less work, if the soil was already prepared in the spring. Seeds are often on sale this time of year.
Many vegetables such as broccoli and cauliflower grown for late season harvest are actually better quality because of the cooler weather when the heads are forming. Some vegetables such as kale, Brussels sprouts, parsnips, and Swiss chard actually develop a better, sweeter flavor after a frost.
Before planting a fall garden, remove any crop or weed residue. Do not work the soil unless absolutely necessary. Plant seeds at the proper depth as instructed on the seed packet. Cover seed with vermiculite or potting soil to prevent crusting of the soil surface. Keep the soil evenly moist with frequent light sprinklings. The upper inch of soil should be kept moist at all times until the seeds germinate.
Keeping seeds moist after planting is more of a challenge in the summer than in spring. However warm soil temperatures promote rapid germination. A light mulch of straw or grass clippings helps to hold moisture. Once seedlings emerge, mulch should be pulled back and watering should be less frequent but more thorough by wetting the top 8 inches of soil.
Late season vegetables include beets, broccoli, cabbage, carrots, cauliflower, snap beans, and summer squash. These can be planted through late August into early September here in central Illinois. Check seed packets for the days until harvest. Our average date of first frost is mid-October.
Cabbage can be direct seeded into the garden. Broccoli and cauliflower are best started in the garden as transplants. Garden centers may not have late season transplants so you may have to search or plant other crops. Most transplants would need late June to mid-July seeding to be large enough to transplant into the garden now.
Other late season vegetables are kohlrabi, leafy crops, and turnips. Leaf lettuce, mustard and spinach can be planted as late as mid-September in central Illinois. Garlic is planted September – October for next year's crop.
Crops such as cabbage, broccoli, kale and root crops can be left in the garden until the weather becomes quite cold. In the fall beets, carrots, parsnips and turnips can be mulched with straw, leaves or floating row covers, left in the garden and harvested into winter. Consider building low tunnels for cold tolerant leafies and a harvest of spring greens.
Please indulge me as I note the passing of an inimitable man, Art Spomer. I first met Art as my plant physiology professor at University of Illinois. As soon as I walked into class I knew this was a rare human. You hear of people having nine lives or possessing many gradations to their personality. Well, Art lived all nine lives simultaneously. Each life lived at both ends of the spectrum and to the nth degree. Scientist and prankster; sculptor and toaster fixer; art lover and dumpster diver; mountain hiker and flatland runner; poet and science writer; fierce debater and compassionate friend; doodler and photographer; army captain and free spirit. I think I heard a cosmic pop when Art passed. The collapse of his influence in so many arenas created a vacuum no one person could ever fill. We will miss you Art.