Extend Your Growing Season into Winter with Cold Frames

If you live in a colder climate, your growing season is likely far shorter than you’d like. Fortunately, there’s a way to extend your gardening season, and that’s with cold frames. Read on to learn how to cultivate hardy winter vegetables and herbs under glass (or plastic) this winter.

Winter Gardening with Cold Frames

Now, when it comes to cold frames, some people go all out and purchase really fancy ones from garden centers or home improvement stores. Others go a more DIY route, and adapt what they have at home to suit their needs.

The best cold frame I ever used was an old dark wooden bookcase from IKEA. It had a hinged glass door on it, which was ideal for providing light, and the dark frame absorbed (and held) heat really well.

I submerged this frame halfway into the soil on my land, and tossed in a fabulous mixture of potting soil, perlite, vermiculite, and well-aged compost. That little cold frame provided me with tatsoi, arugula, beets, turnips, sorrel, savory, and thyme well into January… when the temperature dropped to -35C.

Choose the Right Site

As with all gardening, siting is absolutely vital.

Choose an area that gets at least 6 to 8 hours of direct sunlight every day. Bonus points if you can choose a south-facing locale.

Aim for an area that’s sheltered, rather than exposed. A slope that gets a lot of wind, for example, will result in a frame that gets blasted by cold air on one side. You can imagine how this will affect the plants growing within.

Also, be sure to choose an area that’s not likely to get damaged by falling icicles or a snowy avalanche off your roof. This can crush your cold frame’s glass, which will end up in your vegetables, as well as in the soil.

Cold Frame Details

Winter gardening in cold frames — Photo credit: Foter

An ideal cold frame will have a hinged or removable lid, for easy access as well as air circulation. If you’re building your own cold frame from upcycled materials, search abandoned homesteads to see if you can find discarded windows and door hinges. Also, if you live in an urban setting and you’re feeling adventurous, do some dumpster diving behind TV/film studios.

Commercial and movie sets are built specifically for filming, and all the windows and lumber used for them generally just get tossed out immediately afterward. If there’s a film studio in your city, stop by to see what gems they might have tossed out. Bring a truck just in case.

When planting, leave enough space between your seedlings for air to circulate. If you smoosh them too closely together, you can end up with damping-off disease.

Vegetables and Herbs for Your Cold Frame

Aim for species that can thrive in cold weather, such as brassicas, roots, and hardy herbs. Although some tender greens can do surprisingly well in cooler weather (looking at you here, spinach…), you’ll have a higher success rate with varieties that like cold conditions.

When it comes to choosing winter-hardy varieties, look at those that originate from—or have been cultivated in—places like northern/eastern Europe, Canada, and the northeastern USA. Basically, match the plant’s hardiness zone to your own.

For example, if you’re in zones 4-6 and you’d like to grow kale, aim for a variety like Dwarf Siberian. It’s an heirloom Russian variety that can withstand a lot of cold, and gets sweeter and more tender when exposed to frost. If you try growing an Italian variety like Tuscan (lacinato) kale instead, which is better in zones 7+, you’re setting yourself up for disappointment.

Roots

Beets
Turnips
Rutabagas (Check out the Fortin Family variety from rural Quebec!)
Carrots
Parsnips
Radishes
Celeriac

Greens

Kale
Cabbage
Brussels sprouts (you’ll need a tall, deep cold frame or small greenhouse for these)
Leeks
Mustard
Cress
Arugula
Broccoli
Collard greens
Tatsoi
Mache (corn salad)
Miner’s lettuce
Chard (silverbeet)
Endives