Those of us who grow our own vegetables are accustomed to freshly harvested food, close at hand, delicious and healthy. As the gardening year winds down, we hate to think about going back to eating inferior grocery-store produce. No need! There are a number of tricks to delay that fate and keep the homegrown crops coming even in climates with snowy winters.
As temperatures drop in the autumn, the more tender vegetables (tomatoes, peppers, cucumbers with fruit still on the plant but not quite ripe yet) falter. You can lose them—and any unripe fruit still on the plant—to an early frost.
To get tender plants over the hump of a threatened early frost and productive on into the milder-weather week or weeks that often follow, there are several steps you can take to protect plants from the cold…
Water the garden in the late afternoon— use a sprinkler so the plants get wet from top to bottom. This is an old orchardist’s trick, leveraging the fact that plants freeze at lower temperatures than water. Wet plants often survive a frosty night, even if the water freezes and they become temporarily encased in an icy shell.
Cover plants with “floating row fabric” made of spunbonded polyester (popular brands are Reemay and Agribon). This lightweight material lets in light, air and moisture so you can cover the plants (in groups or entire beds) as the weather gets colder for days or weeks on end, moving it aside only to harvest or provide supplemental water if the weather has been dry. This covering provides a few extra degrees of frost protection, which may be enough.
Drape the fabric gently over the plants, anchoring it in place on the ground with rocks, boards or wire wickets so autumn winds don’t tear it loose or blow it away. You can buy it wherever garden supplies are sold, in rolls or precut sizes. (It’s very affordable—for example, an 83-inch wide, 50-foot long roll is about $28.)
Shelter plants individually. What you use depends on the size/height of the plant. Tents of newspapers or upended cardboard boxes offer overnight protection to taller plants such as peppers and tomatoes. Plastic onegallon milk jugs (bottoms cut off ) can be placed over smaller plants such as strawberries. You want to protect the plants from the cold night but not let the next day’s sunshine cook them. The best approach is to remove during the day and put them back on at night.
Or buy some of the plastic domes (cloches) sold by garden suppliers for this purpose. They look nicer! A set of three sturdy plastic 12-inch cloches—that is, 12 inches high and 13 inches in diameter—runs about $20 at Gardeners.com.
Try the Wall O’ Water (or Kozy Coat or Tomato Teepee). Fill these vertical plastic tubes with water, and place over the plants (you leave them in place). The water inside will absorb heat during the day and radiate it back to the plants they’re surrounding during the cold night. Buy from a garden retailer or catalog. They come in different sizes and often are sold in packs of three or six. A typical three-pack for 18-inch-tall plants usually is $20 or less.
If you’ve had more than enough tomatoes and peppers for one season, rather than extend earlier plantings, you can tear out your fading summer garden and pivot to fall crops…
Salad greens. Try sowing lettuce, arugula, mesclun, spinach, Swiss chard and many Asian greens (tatsoi, etc.). They grow quickly from seeds directly sown into the garden and are fairly cold-tolerant and don’t mind autumn’s reduced sunlight. You can enjoy them before truly cold weather arrives. Use the frost-protection measures described above if winter comes early or you are trying to push your luck with successive sowings.
Cold-tolerant crops. These can be started as seeds during the summer and then transplanted into the ground in fall to produce delicious crops before winter arrives. Good candidates include broccoli, cauliflower and scallions. Some farmers markets offer seedlings of these right when you want them, and some mail-order catalogs also offer seedlings for fall planting.
Pro tip: Source your fall-planting seeds wisely! Skip the standard choices in big seed catalogs or on seed racks in your area. Instead, browse the websites or catalogs of specialty seed companies in northern or high-altitude areas—areas with a short growing season. They select for good flavor and fast growth, and their offerings can just as easily be raised in less challenging, longer-season regions. Some of my favorite sources are Johnny’s Selected Seeds (JohnnySeeds.com) and Pinetree Garden Seeds (SuperSeeds.com) in Maine…High Mowing Organic Seeds (HighMowingSeeds.com) in Vermont… and out west, Seeds Trust (SeedsTrust.com) in Colorado.
While many people do a spring crop of root vegetables such as carrots, beets and potatoes, I encourage a second round in late summer or fall. In both seasons, it is wise to start the plants indoors weeks before you plan to move them into the garden proper.
Alternatively, buy seedlings! Many garden centers and some farmers markets offer seedlings of beets, carrots and more in late summer and early fall. Parsnips and leeks have an even longer growing season and should be sown in late spring or early summer. Either set aside space for these, or fill empty parts of the midsummer garden.
Root vegetables can be harvested well into winter, especially when their rows are deeply mulched. Use mounded-up earth, leaf piles and/or bales of straw up to one foot thick. A little snow cover on top of that, when it arrives, does no harm. You’ll notice that your fall-to-winter harvest often tastes milder and sweeter than the same crops grown in the heat of a summer garden. Spot-checking is the key to knowing when it’s time to harvest. Then harvest as needed or harvest completely if the spot-check confirms they are just the size and flavor that you like.
If you want to get more serious about fall-to-winter food, a versatile and satisfying method is to set up a permanent cold frame, which you can make yourself or purchase. Though these often are used in spring to protect seedlings from cool weather while helping them acclimate to life outdoors, they also are great for fall use. You can easily raise any of the abovementioned fast-growing greens within.
A cold frame is simply a sheltering bottomless box with a transparent lid that you place over the dirt in your garden. There are many cold frame kits on the market, or you can make one out of an old window or attach heavy plastic or fiberglass to a wooden frame—anything that seals the top and lets light through. A minimum size of four feet long and three feet wide accommodates enough of one crop or several similar ones to feed two to four people. Don’t make the box wider than three feet, or you’ll have trouble reaching your harvest!
Make your cold frame higher in the back (1.5 feet) and shorter in the front (one foot). These dimensions allow ease of harvest, while the slope of the lid permits good light collection. Set it up facing south, again for good light, ideally against a house or garage wall or a fence, to mitigate wind and cold. Attach the lid to the taller back of the cold frame with hinges.
You may be surprised at how well plants grow and thrive in a cold frame. Nice pluses: There’s hardly any weed growth, and with the sun at a low angle and not much soil-moisture evaporation, you don’t have to fuss over the plants or water them often. Just be aware that the front needs to be propped open for ventilation on warmer or sunnier days so that the contents don’t cook— intervene when the interior temperature reaches 70°. Install a thermometer or an automatic vent-controller made expressly for this purpose. Gardener’s Supply Company (Gardeners.com) sells one for about $75 or buy one wherever garden or greenhouse supplies are sold. Note: Nonelectric vent controllers like this one can lift only about 15 pounds, so it may not work with a lid made from a heavy old glass window.
Once you’ve tasted success with growing food in cooler weather, you may want to invest in a small greenhouse. Build one yourself, buy a kit or hire a contractor. For heat-retaining efficiency, a useful one should be at least 12-x-20- feet. You could spend $200 to $2,000 or more, and you will need dedicated space for it in your yard.