Cold Weather Vegetables: Winter Gardening Ideas

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Plant cold-weather vegetables such as salad greens, beets, and mesclun with these winter gardening ideas that are perfect for the cold season.

by Kristi Cook

Not quite ready to put away the gardening tools? No worries. With just a bit of planning and a tweak or two to the garden bed, gardeners can enjoy fresh-from-the garden veggies even in the dead of winter.

Winter Crops

Candidates for the winter garden must be cold-resistant, able to withstand cool, moist soil, and be short enough to fit in a cold frame or low tunnel approximately 12- to 18-inches tall. Suitable crops include lettuces, spinach, turnips, corn salad, beets, mustard greens, scallions, Swiss chard, mesclun, and other cool season crops.

Get Growing

Besides cool season crops, the primary key to winter gardening is proper timing. Yet, because hardiness zones and individual sites contain different climates and microclimates, the exact timing of planting will be a bit of trial and error at first. The method I use in my Zone 7 garden is simple. Add the seed’s germination time and days to harvest together. Then, calculate backward from the first frost date to get the date for the first sowing. Each week for at least a month, sow another row to get an idea of what works best for the selected crop, and note any needed adjustments for the next season.

Unlike in the summer garden, this form of succession planting isn’t intended to provide a maturing harvest over multiple weeks, since winter crops basically stop growth once shorter days hit. Rather, its purpose is to determine what stage you prefer each veggie to be at once they go into this winter holding phase.

Then, because plants are more or less dormant, you can harvest all through winter — or until it gets too cold for that particular crop, despite added protection. It’ll also give you an idea as to how much and how long of a harvest can be expected. As with any gardening, you’ll develop a sense of timing for your particular situation.

Winter Gardening Ideas: Cold Frames and Low Tunnels

While winter gardens need protection when the mercury plunges, the goal isn’t to create summer-like conditions. Instead, cold frames and low tunnels limit freeze and thaw cycles by collecting solar heat, blocking chilling winds, and avoiding soaking rains. Temps inside both options often stay 10 to 20 degrees Fahrenheit above outside temperatures, depending on materials used. When temps drop into the low teens, an extra layer of insulation is often all that’s needed to avoid freezing. As with all things, however, each method has its pros and cons.

Cold frames are simple, bottomless boxes no higher than 12 inches or so in back and approximately 8 inches high in front (there’s no hard and fast rule on height, but try to keep it on the lower side to retain heat). For the sides, untreated lumber, bricks, masonry blocks, hay or straw bales, or even river rock work well. Recycled storm doors or windows, shower doors, salvaged greenhouse panels, Lexan, or other clear materials also work well for lids because they let in sufficient light.

Of the two options, cold frames offer the best stability during heavy wind, snow, or rain. Adding extra insulation is a simple matter of placing a heavy blanket or several inches of hay across the top and sides. Venting excess heat can be automated with temperature activated vent openers or performed manually. Once warm weather arrives, you can either move the entire frame to a new location, leave it empty for the summer, or simply remove the top and continue using the box as a garden bed.

The downside to cold frames is primarily cost when used or salvaged materials aren’t available since new materials can be pricey. Also, if you build your box very large, you’ll likely need help moving it to different locations. Windy days can be a problem, too, when the lid is raised for venting, since you could be faced with the added expense of replacing a wind-torn top.

Low tunnels, on the other hand, are more inexpensive as there are few materials required. Translucent plastic sheeting and PVC pipe, rebar, or 9-gauge wire are all that are needed. To add insulation, add more layers, select thicker plastic, or use frost cloth. Relocating tunnels is no problem, either. Just roll up the cover, pull up the wire, PVC, or rebar, and move to a new spot. When not needed, store out of the way in an attic or shed in a dry place out of direct sunlight, which degrades the plastic. Dimensions can easily be altered by adjusting the length or height of framing material.

Low tunnels have their own negatives, as well. While lightweight construction allows for ease of relocation, it also makes it easier for heavy winds to blow coverings loose. To keep heat in and reduce wind damage to the structure, all edges must be either buried in dirt, weighted down with smooth rocks or sandbags, or pinned to the ground. This, in turn, must be undone or redone every time you harvest or need to vent. Last, but not least, if you go with the more inexpensive plastic coverings that are common in home-supply stores, you’ll likely only get a single season’s use. Sturdier commercial varieties are readily available and should last several seasons; however, they’re more expensive.

Ventilate

There’ll be times you have to let excess heat escape by ventilating the box or tunnel. Keep a thermometer in the center and monitor throughout the day. In most cases, outside temperatures of 40 degrees F and higher require venting for at least part of the day. At the cooler end, you may need to lift the lid or tunnel only a few inches. Warmer weather will call for wider openings. Just be sure to monitor temps closely, particularly if a chilling wind is blowing. Make sure to close all openings before nightfall to avoid frost.

Water

Watering plants in cold frames and tunnels will occasionally be needed. Fluctuating temperatures of late fall and early spring demand vigilant attention to moisture levels as evaporation rates will vary dramatically from day to day. During the coldest months, however, little to no additional water will be necessary since moisture loss will be at a minimum. As with any garden, keep a close watch throughout the season. Cool, damp soil is all these plants need.

Each climate allows for slightly different gardening choices, whether it’s cultivars grown or methods used. Therefore, experimentation is key. Expect a few failures along the way; however, it only takes a bit of experience before you’re a pro at winter gardening.

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Kristi Cook lives in Arkansas where every year brings something new to her family’s journey for a more sustainable lifestyle. She keeps a flock of laying hens, dairy goats, a rapidly growing apiary, a large garden, and more. When she’s not busy with the critters and veggies, you can find her sharing sustainable living skills through her workshops and articles.

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Originally published in the November/December 2024 issue of Countryside and Small Stock Journal and regularly vetted for accuracy.