When you’re looking out over a backyard or terrace garden ripe with rich, red tomatoes, deep green cucumbers, multi-color peppers, purple eggplant, and other summer treats, the focus is on making the most of the precious warm weather months. While it’s the last thing on many a gardener’s mind, now is actually the perfect time to get ready for fall harvests.
Spring isn’t the only time to start a crop six to eight weeks ahead indoors. The same setup that got a head start in spring will work equally well, or even better, for fall, as there’s no need to order seeds and dust off the overwintered pots, garden tools, and other sprouting gear. Most of the seeds left over from the spring planting (there are usually way too many in a packet) are the same cool-weather crops that will work exceedingly well as the temperatures drop out of the red. Additionally, it’s an opportunity to implement any lessons learned from the spring sprouting process without having to wait an entire year.
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All seeds need four things: water, to start the germination process; light, such as a sunny window with at least 8 hours of sun a day, or better yet, grow lights set for 18 hours to stimulate maximum growth; oxygen, in the form of a loose seed-starting mix so they can breathe and roots can grow uninhibited; and heat.
However, when it comes to that last factor, there can be too much of a good thing. While summer crops such as tomatoes can sprout in temperatures ranging from 50 to 90 degrees F, most plants prefer 65- to 70-degree temperatures. In the spring, this means a warm spot in the house or a heating mat. In the summer, on the other hand, locate them in either a cool spot inside the residence (away from the harsh air flow of air conditioning vents) or otherwise keep the temperature down.
One way to do this is with fans. The increased air circulation has the added benefit of reducing the potential for fungus and mold while strengthening the stems, since the simulated “wind” makes the sprouts buff up as they grow. Watering plants adequately will also keep them cooler.
Set a thermometer nearby to help maintain optimal conditions. Or better yet, use the old electronic thermostat saved when the prior whole house air conditioner was replaced; it’s a free, highly accurate option.
A fan can be used to simulate wind and make indoor seedlings grow stronger. tong patong/Shutterstock
Scrumptious Selections
Whether utilizing leftover cool-weather plant seeds from spring or ordering new seeds, keep in mind that for most of the country, the fall season ends in an eventual hard freeze. The key is to start by determining the first frost date and counting backward.
Some areas in the far north of the United States can have first frosts as early as late-September. When in doubt, choose vegetable varieties with the fewest days to maturity. Also, keep in mind that some, such as lettuce, spinach, mustard greens, green onions, leeks, carrots, beets, and turnips can be picked young, while others, like cauliflower, broccoli, and radishes need to develop fully.
Turnips can be picked young, making them ideal for fall harvesting before the first frost. Nadia Nice/Shutterstock
Happily, broccoli and cauliflower, as well as lettuce, mustard greens, and spinach, can handle a light frost. Radishes, beets, kale, collards, and green-bunching onions are even brawnier and may withstand a hard frost. If there’s sufficient temperate weather left in the season, consider increasing the harvest by planting different types with different maturity dates, or plan on starting a second seedling crop in 30 days to take advantage of succession planting.
Outdoor Conditions
Most gardeners associate the term “hardening off” with spring, when, prior to planting in the ground, plants are brought outside for a week or two to acclimatize in a shady, protected location, and brought in at night when the temperatures drop below 50 degrees F. This allows the plant to shift from the soft, overly succulent indoor growth to firmer, more resilient stems.
Fall hardening off also requires the plants to be slowly acclimatized for a week or two prior to planting in the ground, but in this case, they’re getting gently introduced to weather that may be slightly warmer than their ideal temperature. Fall plants should be placed in a shady location, increasing the amount of sunlight they get each day. If the weather is still breaking records, they may need to be brought inside at midday for at least the first few days. Also, unlike spring plantings, fall seedlings can be left out overnight from the start, unless there are high winds.
Not Convinced?
Many gardeners swear that brassicas—such as cabbage, kale, kohlrabi, Brussels sprouts, and collards—are sweeter after a frost. Plus, there’s less pest pressure to deal with. What are you waiting for?
Contained Goodness
When starting seeds for fall, don’t forget to plant some for any container gardens that would otherwise go dormant until spring.
Crunchy Delight
Celery lives its best life in cooler temps, but it takes 90 to 130 days to harvest, making it an ideal container plant. Start transplants 10 to 12 weeks ahead, and be prepared to bring them indoors during unexpected cold snaps.
Surprise Treat
Roast Brussels sprouts in the oven until they’re caramelized a bit for a true winter delight after the general garden is put to bed. These persnickety plants require temps under 80 degrees F, but can survive a 20-degree chill, and thrive in a container environment.
Long-Term Investment
Perennial asparagus takes its sweet time getting started. It’s best not to harvest it for two or three years, but then it will produce for over a decade. Its ability to live life as an indoor-outdoor container plant is its secret to being able to grow just about anywhere.
Sandy Lindsey
Author
Sandy Lindsey is an award-winning writer who covers home, gardening, DIY projects, pets, and boating. She has two books with McGraw-Hill.
