What’s an overwintered crop? It’s a clever way to foil Mother Nature (and impress your neighbours!), and harvest months before the ‘normal’ planting season of late spring. It involves direct seeding cool and cold season veggies – typically leafy greens – in early autumn. They are then protected with a simple structure or insulating materials until they are ready to harvest in March and April.

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1) Mulching

The easiest, quickest, and cheapest overwintering technique is to use a mulch of straw or shredded leaves. This requires a slightly earlier planting date than with the mini hoop tunnel approach, as mulched plants will come through the winter better if they are at least semi-mature. Therefore, sow seed four to six weeks before the average first frost date. Then, when the temperature is hovering near freezing on a regular basis, mulch the young plants with about a foot (30 cm) of organic materials. Cover with a row cover or bed sheet to keep the leaves and straw from blowing away and say good night until March.

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2) Mini Hoop Tunnels

My favourite way to overwinter greens is with a mini hoop tunnel. I use these handy and quick-to-build structures all year long: in early spring to get a jump start on the garden, in mid-summer they’re covered with shadecloth to delay bolting for salad crops, in winter they create a microclimate around tall crops like kale, leeks, and collards. But, mini hoop tunnels are also ideal for overwintering. They allow plenty of light to reach the crops, which jump-starts growth as the day length increases in February.

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My tunnels are made from lengths of 1/2-inch (1.25 cm) PVC conduit bent in a U-shape over my 4 by 10-foot (1.2 by 3 meter) garden beds. Each end of the conduit is slipped over a 1-foot (30 cm) rebar stake. A center support sheds snow and a cover of 6 mil greenhouse plastic blocks winter wind and traps solar energy. The beds are seeded in late September to early October, but are not given their winter covers until November. (Full details on my mini hoop tunnels and other winter harvesting techniques in my best-selling, award-winning book, The Year Round Vegetable Gardener).

Growing winter vegetables: Overwintering superstars!

I’ve grown a wide selection of vegetables in my overwintering tunnels, but focus mainly on hardy greens like spinach, arugula, mache, claytonia, mizuna, tatsoi, mustard, kale, and endive. Once you’ve chosen the type of crop you want to grow, further whittle your selection to the most cold-tolerant varieties. Find out which are the best winter picks by reading your seed catalogues and packets carefully. For example, ‘Tyee’ is an outstanding cold hardy spinach that winters better than ‘Bloomsdale’.

Are you growing winter vegetables in your garden?