Winter Greenhouse Gardening

At this time of year, I’m usually kicking myself for not preserving more of the summer and autumn harvest. A long winter absent of fresh, local produce typically looms large as the days shorten and the temperature drops. But this year, I’ve taken matters into my own hands and made the decision to grow food straight through the winter—on my back porch.

Cold-weather gardening

In his latest book, The Winter Harvest Handbook, cold-weather farming guru Eliot Coleman outlines how smart plant selection and protected cultivation lead to successful winter growing. While a February crop of tomatoes is far-fetched, a winter harvest of kale, carrots, radishes, a variety of herbs, lettuce and much more—Coleman grows 30 winter crops—is achievable.

For the backyard or balcony gardener this means buying cold-hardy vegetable seeds or starts and covering the crops to protect them from winter winds and frost. (Although some crops become sweeter after a frost.) Coleman uses standard plastic covered hoop houses in his yard, and often ads a second layer of protection with a lightweight floating row cover. The temperature on his Maine farm can fall to -20°C, yet those two layers temper the cold just enough to allow the soil to retain its warmth and the crops to thrive.

Coleman’s techniques work well with a steady supply of winter sun, but my north-facing back porch enjoys zero direct sunlight beyond Labour Day. So I decided that I needed to find a system to compensate. Luckily, I stumbled across a company on Vancouver Island that builds mini greenhouse systems, and they were looking for a variety of settings to test their units. So my back porch has now become the site of a cold-weather gardening experiment.

Desperately seeking light

SunPod Greenhouses work well on their own in locations with adequate sunlight, but they are also designed to integrate grow lights right into the unit. There are a variety of models of different shapes and sizes that retail for $399 and up. For those with garden space, SunPod also supplies backyard-scale “ultra light arches” in sets of three for just over $150. If you’re a Do-It-Yourself-er, any well-stocked garden centre or farm supply shop will have all of the supplies necessary to rig up your own system.

The compact SunPod unit I’m using is built from Forest Stewardship Council (FSC)-certified Western red cedar and tucked into a corner of my back porch. It’s my gateway to fresh homegrown produce, decked out with grow lights, heat mats and a self-regulating “smart vent” that opens and closes based on the inside temperature. While this is surely the high-end of backyard greenhouses, it allows for a wider range of crops to be grown. My winter crops include cilantro, beets (for greens), sage, French tarragon and basil. That’s right, basil!

Push the limits of harvest season

If you select the right plants, protect them from the harshest winter elements and ensure they receive adequate light, you too can enjoy a winter harvest straight through until the first crops of spring emerge.