Growing cool-season vegetables in the fall
August 26, 2010
  • /Crop Sciences
As most gardeners are busy harvesting many warm-season vegetables during the summer, it might be hard to believe that yet another vegetable season is just beginning, said a University of Illinois Extension horticulture educator.

"Fall's cooler weather presents a great opportunity to grow a crop of cool-season vegetables," Matt Kostelnick said. "These vegetables include lettuce, spinach, radishes, broccoli, peas, onions, chard, cabbage, carrots, and more."

While most people grow these vegetables during the spring, such crops can also grow during the fall in Illinois.

"Many people grow cool-season crops in spring because they are eager to get in the garden and begin growing something," Kostelnick said. "The fall is often overlooked for growing cool-season crops, but it is a great time to take advantage of the cool weather and extend the growing season. If they plant in the fall, gardeners can easily grow vegetables for nine months out of the year, from March until November."

Several cool season vegetables are better suited to the cooler temperatures of fall than spring. Fall frosts can actually enhance the flavor and texture of some vegetables, such as chard, kale, turnips, mustard greens, parsnip, salsify, spinach and rutabagas.

Because cabbage and Brussels sprouts do not develop well in hot weather, they are constantly threatened by warmer temperatures when grown during the spring. On the contrary, such crops grown during the fall can develop the edible heads without the threat of hot summer weather.

"This concept applies to many other cool-season vegetables," Kostelnick added. "While most cool-season crops can be harvested in fall, certain vegetables, such as asparagus and rhubarb, can only be harvested in the spring."

Fall vegetables are typically started from seed and planted in late July and August. With these vegetables, gardeners should take advantage of succession planting. Succession planting involves planting multiple sets of the same crop on different dates. For example, radishes are very easy to plant in succession. One crop of radishes can be planted in late July, another in mid-August, and another in early September. These successive plantings allow for an extended, gradual harvest of radishes, as opposed to harvesting all at once.

Fall broccoli can be started from seed or transplants in late July and August. Brussels sprouts and cabbages can be started from seed in early July, preferably in a part of the garden protected from hot sun. Five weeks later, the seedlings can be transplanted to parts of the garden with more exposure.

"These vegetables begin growing under warm conditions, but the edible heads develop under cooler conditions, making them ideal fall crops," Kostelnick said.

The following crops can be planted from seed in mid-summer and harvested throughout the fall: kale, Chinese cabbage, chard, radishes, collards, beets, kohlrabi, leaf lettuce, spinach, and turnips. Some of these vegetables, such as kale and spinach, are especially hardy and may grow into December.

Other cool-season vegetables have different growing patterns. Rutabagas should be planted early in the summer while parsnips, salsify and Jerusalem artichoke are planted in the spring, grown throughout the summer and not harvested until late fall, Kostelnick said.

"Garlic is planted several weeks before the ground freezes, typically in November, and is not harvested until the following summer," he added.