As the end of summer approaches, it’s hard to think about vegetables tended with such care during the growing season withering with a single cold snap. Luckily there are ways to preserve summer’s bounty well past the season’s end. Here are seven ways to keep your garden growing right through the fall.
1. Plant late season and cold hardy vegetables.
Many gardeners plant their entire garden in the spring and put things to bed once the cold weather hits. There is another option to growing only summer crops, however.
Late season plantings
Late season vegetables go into the ground in late summer and early fall. They tend to grow quickly, benefitting from the cooling temperatures that keep them from going to seed. In some cases, these crops include varieties that do well in the springtime as well. Most late season varieties have some cold tolerance, but they do best when harvested before the deep freeze sets in.
Popular late season veggies: salad greens, Swiss chard, beans, peas, carrots, radishes, spinach, bok choy and cabbage.
Cool season crops
Cool season plants are cold hardy. This means they can tolerate cold temperatures, frost and even a little snow. Plant these crops towards the end of your growing season and keep harvesting them as long as they last. While they won’t do much growing once the mercury dips, they’ll hold in the garden (or greenhouse) longer than regular season crops.
Popular cold hardy veggies: broccoli, cabbage, Brussels sprouts, scallions, kale, leeks, beets, turnips, carrots and parsley.
Related: Winter Gardening: Best Crops to Extend Your Harvest
Cold hardy vegetables like those in the Brassica family will tolerate chilly temperatures. Photo by Marta Reis from Unsplash.
2. Look for microclimates.
Have you ever noticed that your garden doesn’t act the same way as your friend’s across town? Or that despite the restrictions of your climatic zone, your property tends to fare better when the frost hits? Depending on the shape of your yard and where it’s located, your garden may be sitting in the middle of a microclimate.
A microclimate is a small area with a growing climate that differs from the surrounding region. If your garden is protected by a nearby wall, or it sits in a hollow away from cooling winds that affect soil temperature, you may be able to grow earlier and longer than open, exposed areas.
To take advantage of microclimates, plant fall crops near walls that absorb and radiate heat (such as those made from concrete or brick) or next to structures that block prevailing winds. Choose south facing slopes for the best sun exposure, and avoid planting in deep, shady areas where frost may linger.
3. Mulch your crops.
Carrots, cabbage, parsnips, beets and more: depending on your climate, many vegetables will stay plump and firm in the garden long after fall’s chill sets in. All they need is a little protection from extremes.
Adding a thick layer of organic mulch is one way to keep root crops in the garden just a little bit longer. The insulation from materials like straw, seaweed or autumn leaves helps trap heat and keep out the bite of winter’s chill. It modulates the temperature in your garden’s top layer of soil, protecting crops from the freeze-thaw pattern common in fall weather. While plastic mulch can be helpful in the spring as the soil warms, it doesn’t offer much fall or winter protection. It also ends up in the landfill.
Mulching around the base of crops will help protect the soil and your plants’ delicate roots.
In addition to safeguarding plants and building soil health over time, organic mulch protects soil microorganisms from the cold. The longer they work, the more your soil will benefit. Plus, areas that receive lots of fall rain (we’re looking at you, Pacific Northwest) can lose precious soil through seasonal erosion. Mulch helps with this, too.
4. Add floating row covers.
Floating row covers are like a blanket for your veggies. When nighttime temperatures threaten to end your harvest, pulling up a layer of this wondrous garden fabric can help keep your plants frost-free.
Made from spun polypropylene, this thin, white material allows both light and water to pass through to your vegetables while providing protection from temperature extremes. Lightweight floating row cover is perfect for pest protection and preventing greens from bolting in the summer heat. Heavyweight row cover works best to protect early- and late-season crops from frost. Both are useful for keeping out insects and other pests.
For temporary frost protection, drape floating row covers directly on top of plants and secure with rocks or landscape staples. During the cool nights of autumn, this simple layer can increase the temperature for your plants up to 10 degrees. If your winters are mild, use heavyweight row covers over a sturdy frame to preserve cold hardy vegetables like kale right through until spring.
5. Use cloches or cold frames.
When floating row covers aren’t quite enough, it’s time for another level of protection. Portable garden cloches are like mini greenhouses. Originally made from glass and shaped like bells, they’re now usually made from clear plastic and supported by metal or PVC hoops. This super-light construction makes them fairly portable, just right for slipping over a plant or row when frost threatens.
Cold frames are larger, sturdier and usually heavier than cloches. They are often made from polycarbonate panels, glass, and even scrap materials like old windows. Gardeners often install cold frames sheltered areas for long-term protection–such as protecting spring and fall greens for the shoulder season. A door or lid on cold frames makes them easy to vent when the temperatures fluctuate.
Adding one of these two structures to your crops will increase daytime temperatures close to your plants, buffering the leaves and roots from the cold. It will also help insulate closely-spaced plantings. Just be sure to clear snow and frost from the surface of cloches and cold frames to ensure your plants benefit from daytime sunshine.
6. Add a greenhouse.
If you have the space, a greenhouse is a surefire way to protect plants right through the winter. Larger than cold frames and cloches–and capable of raising temperatures by up to 30 degrees (you heard that right!)–greenhouses have been the structure of choice for over two hundred years.
Greenhouses work like cold frames, but on a larger scale. They trap the sun’s heat when solar radiation passes through the clear walls, heating up whatever is inside. This includes walls, frame, soil and plants. Rising warm air can’t escape, so the temperature inside a greenhouse stays warmer than outside.
While there are many ways to use a greenhouse, the main incentive for many gardeners is a longer growing season and carefully protected crops. Double the protection by adding a floating row cover to your greenhouse crops, and you can grow cold hardy plants even in the chill of winter–without added heat.
Adding a greenhouse will help extend your gardening season right into winter. Pictured: Riverstone Monticello Greenhouse
7. Grow plants indoors.
While indoor vegetable gardening isn’t as bountiful as its outdoor counterpart, select vegetables will perform well when given the right conditions. Whether you start seeds indoors or bring established containers into a heated space, light and warmth are the key factors to success.
Vegetables that grow successfully indoors (such as lettuce, Swiss chard, tomatoes and tendril peas) require at least 8-12 hours of bright sunlight each day. More is better! If you don’t have a sunny (preferably south-facing) window that receives this much direct light, you can dose your plants with a grow light to make up the difference. To grow more in a smaller space, consider one of the many hydroponic grow cabinets available.
Tomatoes, Swiss chard and salad greens are some of the vegetables that can be grown indoors under the right conditions.
Choose a space away from drafts, heaters and tiny fingers. If you’re starting new seeds, use a growing medium meant for sprouting seedlings (e.g. a seed starting mix). Fertilize salad greens with liquid fertilizer after each harvest.
Frequently asked questions
How do you protect crops from too much heat?
More and more gardeners are having to contend with soaring temperatures and heat waves. In southern regions, these extremes now extend into fall, stressing plants and causing them to bolt or die. The best way to protect late-season crops from excess heat–particularly greens–is by using a shade cloth.
What is pop-up crop protection?
For those times when the weather forecaster is calling for a freak frost, pop-up crop protection offers temporary relief for tender plants. These mini-structures are light, portable, small and easy to transport. Pop over your plants when a cold spell is expected and remove again when the threat has passed.
What’s the difference between a polytunnel, hoophouse, and greenhouse?
What you call these different structures depends somewhat on where you’re from, but generally speaking, a greenhouse is the classic, durable and often permanent structure made from glass or heavy plastic that provides year-round crop protection and excellent heat retention. A polytunnel or hoop house is a smaller, less permanent (and often less expensive) option for backyard gardens and small-scale farms. It consists of a thin steel structure covered with plastic sheeting, often in an elongated half circle.
What are the best fall high tunnel crops?
High tunnels look a lot like greenhouses, but they’re generally tall enough for machines to work inside. Plants are usually sown directly into the ground, rather than into pots or flats on tables. They may also be more portable than greenhouses as they’re made from ultra-light materials. Popular crops to plant in high tunnels include kale, spinach, lettuces, radishes, beets, turnips and carrots.
What’s the best row cover for raised garden beds?
Most heavyweight row covers made from polypropylene will work for crops grown in raised garden beds. Check that your chosen row cover weighs at least 1.25 oz/square yard. According to the College of Agricultural, Consumer and Environmental Sciences at New Mexico State University, this weight will permit enough light for optimal plant growth while still providing good frost protection.
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