This past July, popular seed companies announced that it was time to start the fall vegetable garden but I dismissed it as it was high summer and I was rolling in red tomatoes and yellow peppers. Now, as the tomato plants begin to yellow and the peppers turn red, I am focusing my attention on cool season veggies in hopes of reliving the greens I enjoyed this past spring. I did not plan for it though, it caught me by surprised. August is a time for harvesting and processing the summer bounty while at the same time planting another round of seeds for the fall/winter/spring edibles, depending on what you plant and if you can extend the season with covers. I was fortunate enough to have seed left over from the spring and planted pak choi, sugar snap peas, lettuce, scallions, spinach, and carrots both in the garden bed and in containers.
Last weekend I attended a 90-minute presentation called “Fall Vegetable Gardening,” where Libby Good, a Virginia Cooperative Extension Master Gardener, expanded the concept of fall vegetable gardening to include planting crops to harvest before frost or that can overwinter, planting cover crops to add nitrogen, extending the season with cold frames or row covers, garden clean up, and overall getting ready for the next year. Libby explained that planting in the fall has advantages: the soil is workable, the air temperatures can be cooler with less direct sun, the moisture levels can be higher, and there can be fewer insects and weeds. “Most fall veggies don’t rely on pollinators and are high in nutrition,” she said.
Libby also explained that if you are starting seed or buying transplants you have to first determine your frost date, which Libby says is around Halloween in the Northern Virginia area. Then you have to work backwards to determine when to plant the seed or transplant. But the difference between fall and spring planting is the “Short Day” factor, which usually is not addressed on a seed packet. If you are going to plant seed, you have to add 2 weeks to the numbers on the seed packet to allow for the cooler night temperatures and the shorter day lengths. According to her handout, if you want to sow spinach seeds for a fall harvest (i.e., before first frost), you have to add the 7 to 10 days for germination, 35 days to reach maturation, and 14 days for the Short Day factor for a total of 56 to 59 days. Therefore, the latest you can sow seeds is the beginning of September. The length of time would be shorter if you bought transplants from a nursery.
Another factor to keep in mind is the plant’s tolerance for cold temperatures, for example, beets, cauliflower, chard, Chinese cabbage, endive, kohlrabi, lettuce, mustard, peas, and rutabagas can survive light frosts. Broccoli, broccoli raab, Brussels sprouts, cabbages, collards, kale, radishes, spinach, and turnips can survive heavy frosts. Chicories, garlic, kale, leeks, multiplier onions, spinach, and shallots can stay in the ground over winter.
You can extend the season, which means to be able to harvest after frost, by protecting the plants from low temperatures with row covers, cold frames, hoop houses, and greenhouses. Libby has been gardening for many years and uses both row covers and cold frames to extend her harvest. She passed around her own row cover, made out of a synthetic fabric that allows light and water through and provides several degrees of protection. She also showed photos of her cold frames which she made with discarded windows. By growing greens in a cold frame she was able to harvest lettuce in February.
“Fall Vegetable Gardening” was free, courtesy of the Virginia Cooperative Extension and Master Gardeners of Northern Virginia, and will be offered again on Thursday, September 4, at Fairlington Community Center, 7:00 to 8:30 pm; and Saturday, September 20, 10:30 to noon at the Barrett Branch Library. Call (703) 228-6414 or e-mail email@example.com to register in advance. http://www.mgnv.org