Fall Vegetable Gardening

• Hardy crops (will withstand a hard frost): broccoli, cabbage, lettuce, pea, turnip, kale, spinach, broccoli raab, arugula, endive, escarole, radicchio, mizuna, tatsoi, bok choy, spinach, kale, and turnip greens.
• Half-hardy crops (will tolerate light frosts): beet, carrot, Swiss chard, mustard greens, radish, and cauliflower.
• Alliums: garlic, shallot, and multiplier onion can be planted in October for harvest the following spring/summer.

Cool-season crops take advantage of warm late-summer weather that spurs strong, early growth. The cooler temperatures that follow benefit these crops as they reach maturity. Frosts increase the sugar content and improve the flavor of many cool-season crops, and the starch to sugar conversion also makes the plant more cold-hardy. Plants such as looseleaf lettuce, radish, arugula, mizuna, and tatsoi grow quickly and can be planted several times from late August through late September for a continuous harvest.

• Daylength decreases a few minutes each day during the fall gardening season, so it is critical to plant early enough to get plants well-established before temperatures cool down. The combination of reduced sunlight and cooler temperatures slows plant growth. (Vegetable growth is very limited when the total amount of sunlight per day drops below 10 hours. In Maryland, this is about mid-November through late January.)
• It can be difficult to source high-quality transplants to buy, so plan to grow your own by starting seed indoors or outside in a protected, part-shade location.
• Lettuce and spinach seeds are difficult to germinate when the soil temperature is above 70°F, so wait until the summer temperatures cool before planting.
• Peas are difficult to grow in the fall because of high soil temperature and insufficient time for plants to produce pods prior to cold weather.
• Seedlings and transplants may need protection from insect pests, bright sunlight, and high temperatures. Learn more about using row cover, insect netting, and shade cloth in the Vegetable Garden Weather and Pest Protection page.
• Heavily-fertilized leafy greens can accumulate excessive nitrate under low-light conditions, posing potential health risks. Use compost and organic fertilizers sparingly on protected leafy greens that will be harvested from December through February.

• Spread ½ to 1 inch of compost on top of the bed prior to planting.
• Keep seedbeds evenly moist: seeds should not dry out as they germinate.
• Fertilize as needed once plants are established.
• Weed regularly and mulch exposed soil to keep new weeds from sprouting.
• Thin crowded plants to the recommended spacing for best growth and plant health.
• Use cold frames and row covers to nurture plant growth and provide some cold protection to extend the harvest period. Learn more about cold frames:
  • Building and Using Hotbeds and Cold Frames | University of Missouri Extension
  • Building a Coldframe or Hot Bed | University of Nebraska Extension
• Harvest beets, turnips, and carrots through December by covering the bed with an insulating mulch to prevent freeze damage to the roots.
• Fall crops that overwinter with protection and resume growth in spring include spinach, arugula, kale, mâche (corn salad), parsley, and chicories (radicchio, escarole, endive).

Each vegetable cultivar has a “days to maturity” number which appears on the seed packet and in catalogs. It refers to the number of days from seeding in the garden to harvestable maturity for crops like lettuce, spinach, beet, radish, and leafy greens; and the number of days from transplanting to maturity for crops like broccoli, cabbage, cauliflower, and Brussels sprouts. These days to maturity numbers increase for fall crops due to decreasing light and lower temperatures that slow growth.

The Short-Day Factor (SDF) helps to compensate for the light and temperature differences (although other environmental factors also affect maturity dates). Calculate the proper planting date by including a SDF of two weeks (14 days). You can use transplants for crops that are normally direct-sown, which will let you plant later into the fall – but don’t wait too long. Fall crops often fail because they are planted too late. The SDF is especially critical for crops that produce heads or pods; less so for root and leafy crops.

Example: You want to start harvesting beets on October 15th. The seed packet says 55 days to maturity. When should you plant?

1. Take the desired harvest date (October 15) and subtract the days-to-maturity time (55 days). This would be August 20.
2. Subtract the SDF (14 days) from August 20 to get August 7.
3. Plant seeds around August 7.

Additional resources

Floating Row Cover | University of Wisconsin

Row Covers for Vegetable Gardens | Washington State University

Using Row Covers in the Garden | University of New Hampshire