Not everything has to come out before winter. Several hardy vegetables happily sit in the ground through a Canadian winter, and a few actually taste better after a hard frost turns their starches to sugar. Here is what you can leave, how to protect it, and how far north it works.
Root crops: harvest through the cold
Carrots and parsnips are the classic overwintering roots. Frost sweetens them dramatically. In milder zones you can dig them all winter as long as you can get a fork in the ground; in colder zones, mulch heavily and harvest before the soil freezes solid, or leave them mulched and dig in early spring.
- After the first hard frosts, pile 8 to 12 inches of straw or shredded leaves over the row.
- The mulch keeps the ground diggable longer and stops the roots from turning woody.
- Parsnips especially are often left until spring on purpose; overwintered parsnips are wonderful.
Hardy greens: they shrug off frost
Kale, leeks, and Brussels sprouts stand up to serious cold and sweeten with it. Kale will often keep producing into December in milder zones and survive under snow to regrow in spring. Leeks can be mulched and pulled as needed through much of the winter. In the coldest prairie and northern zones, snow cover is what makes this work, an insulating blanket of snow protects far better than bare exposure to wind chill.
Plant-now, harvest-next-year
Two crops are meant to overwinter by design:
- Garlic is planted in fall, sits dormant all winter, and is harvested the following summer. (See our fall garlic guide.)
- Spring bulbs and some hardy herbs (chives, sorrel, established thyme) come back on their own; a light mulch after freeze-up helps.
How to protect an overwintering bed
- Mulch after the ground starts to freeze, not before. The point is to keep the cold steady, not to keep the soil warm.
- Straw, shredded leaves, or evergreen boughs all work. Thicker in colder zones.
- Mark your rows before the snow flies so you can find the carrots in January.
- Row cover or a cold frame extends the harvest window for greens in exposed gardens.
What NOT to leave out
Frost-tender crops, tomatoes, peppers, squash, beans, basil, are done at the first frost and should be pulled. Potatoes should be dug and stored; left in the ground they rot or freeze. When in doubt, if a plant is a warm-season annual, it is not overwintering.
Overwintering is the laziest kind of gardening: you already did the planting, and the cold does the rest. A thick mulch and a marker stake, and you can be pulling sweet carrots out of the snow while everyone else is waiting for spring.