Planting a fall vegetable garden
August 4, 2016
  • /ACES
  • /ACES News
  • /Crop Sciences

URBANA, Ill. - Planting a vegetable garden doesn’t just happen in the spring. “Many of the vegetables that we grow in the spring can be planted in late summer or early fall,” says University of Illinois Extension horticulture educator Ken Johnson. 

“By the time summer rolls around many of our cool-season plants that were planted in the spring are past their prime,” says Johnson. “They become tough and bitter and will often bolt, like radishes and spinach. By planting these cool-season crops again, you can extend your gardening season and have fresh produce longer.” 

Johnson says there are several other advantages to planting a fall vegetable garden.

“There are often fewer pest and weed problems in the fall compared to the spring. Many vegetables have better quality when they are grown in the fall.  Some vegetables develop better flavor when grown in the fall, particularly after they have gone through a frost. Fall gardens often require less time and labor because the soil has already been worked in the spring.” 

According to Johnson, vegetables that are typically grown in a fall vegetable garden fall into the semi-hardy and hardy categories. Semi-hardy plants, such as beets, carrots, cauliflower, and lettuce can tolerate light frosts as low as 32 degrees F.  Hardy plants, such as broccoli, cabbage, radishes, and spinach can tolerate hard frosts down to 28 degrees F.  

“To determine when you should plant your vegetables, you need to determine when your first frost usually occurs,” Johnson says. “For central Illinois it is generally mid-October.  Start with that date and count backwards for the number of days it takes the crop to mature. It’s wise to add a week or two for the fall factor because temperatures are getting cooler. Development slows compared to spring when temperatures get warmer.”

Most of the vegetables grown in the fall vegetable garden, Johnson says, can be directly seeded in the garden. Some vegetables, like broccoli and cauliflower, are best done as transplants. “Unfortunately, transplants are not easy to find in the summer for these plants, so to make your own, start the seed indoors 6 to 8 weeks before you want to plant them in the garden.”

Before planting a fall garden, Johnsons says to clean it. “Remove any crop residues from previous crops and pull any weeds that may be present. Soil can also be tilled and 1 to 1 ½ pounds of an all-purpose fertilizer (per 100 square feet) or composted organic matter can be incorporated. When planting seeds, follow the directions on the seed packets. Make sure to keep the soil moist until the seeds have germinated. Because the seeds are being planted at the end of summer, the soil moisture will need to be monitored closely.”

According to Johnson, a light covering of mulch or even a board can be placed over the seeds to help retain moisture in the soil. If using a board, he says to remove it after the seeds germinate. “Checking the seed packet will give you an idea of how many days it will take for the seeds to germinate. Make sure to check under the board frequently for sprouting seeds. It’s helpful to provide some shade to seedlings in the afternoon while the temperatures are still high and the plants have yet to become well established. After your plants have become established, the maintenance is just like any other garden.  Make sure to control weeds and pests if necessary, and water when needed.”