Cultivating cool-weather vegetables in the fall allows gardeners to significantly extend their harvest, often continuing to pick fresh produce well into late autumn and early winter. Unlike high summer, the milder temperatures of the fall season naturally reduce the activity of many common insect pests and plant diseases. Establishing a garden in late summer and early fall also utilizes the cooling soil temperatures, which benefit root development and result in sweeter-tasting greens and brassicas.
Calculating Planting Dates
Successful fall gardening relies on precise timing, which requires counting backward from the region’s average first frost date. This date is the benchmark for planning, as most vegetables must reach harvestable size before the arrival of a hard freeze. To determine the final safe planting day, locate the crop’s “Days to Maturity” (DTM) listed on the seed packet. The DTM, which is calculated for spring conditions with increasing daylight, must be adjusted for the decreasing daylight hours of fall.
A two-week buffer (10 to 14 days) must be added to the stated DTM to account for the slower growth rate as the days shorten and cool. This adjusted maturity time is then counted backward from the average first frost date to establish the latest possible planting day. For example, a crop with a 50-day DTM should be planted at least 64 days before the first expected frost to ensure a mature harvest. Planting too early during mid-summer can cause cool-season crops like lettuce and spinach to “bolt,” or prematurely flower and become bitter due to excessive heat.
Fast-Maturing Crops for Quick Harvests
Crops that reach maturity in 60 days or less are ideal for direct sowing in late summer. Radishes are the fastest option, with many varieties ready for harvest in as little as 21 to 28 days. These root vegetables should be sown about half an inch deep and require aggressive thinning to about two inches apart, which prevents competition and ensures the development of a plump, edible root. Succession planting, or sowing a small batch of seeds every two weeks, will provide a continuous supply throughout the fall.
Leafy greens, such as arugula, spinach, and loose-leaf lettuce, are also rapid growers and can be harvested in the baby leaf stage in under a month. Arugula offers a peppery flavor and is often ready in 30 to 40 days, while spinach varieties like ‘Bloomsdale’ can be picked in as few as 28 days. For loose-leaf lettuce, planting seeds thinly and then thinning the seedlings to a final spacing of four to six inches allows for the “cut-and-come-again” harvesting method, where outer leaves are removed while the inner crown continues to produce.
Quick-growing root crops like beets and turnips can also be sown directly into the garden for a harvest in about 50 to 60 days. Both are dual-purpose, offering edible roots and greens; beet roots are ready when they are between one and three inches in diameter. Scallions, which are immature onions, can be grown from sets or seeds planted in the fall, yielding green onions in a relatively short timeframe.
Hardy Crops Requiring Earlier Sowing
Crops that require a longer growing period (60 to 100 days) must be started earlier to establish sufficient growth before the reduced daylight slows them down. This group is dominated by the brassica family, which thrives in cooler temperatures. These plants are highly cold-tolerant and many develop a sweeter flavor profile after being exposed to a light frost. The brassica family includes:
- Broccoli
- Cabbage
- Kale
- Collard greens
To ensure a harvestable head of broccoli or cabbage before the hard freeze, seeds are often started indoors six to eight weeks before the target transplant date in mid-to-late summer. Transplanting small seedlings rather than direct-sowing gives these longer-season crops a necessary head start to maximize their vegetative growth period. Brassicas are susceptible to pests like the cabbage worm, requiring a gardener to cover young plants with row covers immediately after transplanting to physically block egg-laying moths.
Snap peas and shelling peas are well-suited for a fall crop and require 55 to 70 days to reach maturity. Fall peas are generally sweeter than their spring-planted counterparts due to the cooler temperatures during their development. Overwintering crops, such as garlic and specialized onion sets, have a distinct planting window in the fall, with the intent to harvest the following spring or summer.