You don’t need a heated greenhouse to grow fresh vegetables in winter; there are many simple season extenders and techniques that can take your garden from summer to fall to winter. In my books, The Year-Round Vegetable Gardener and Growing Under Cover, I share the various crop protectors and winter vegetables that allow me to enjoy a year-round harvest in my zone 5 garden. Maybe you’re already a winter gardener and have planned and planted for the cold season? Or, you’re new to season extending and are wondering if it’s too late to establish winter crops? Read on; I’ve got three easy ways to help you harvest into winter.
1. Protect what you’ve got. By the time summer shifts to fall, most vegetable gardeners still have some crops left in their gardens; root crops like carrots, beets, and parsnips, leafy greens like spinach, arugula, and kale, and stem crops like leeks, brussels sprouts, and scallions. Don’t let them die in the hard frosts. Instead, protect them with a mini tunnel, strawbale cold frame, or layer of mulch. It will extend your harvest by weeks, or even months, depending on the crops and which type of protection you use.
- Mini tunnels can be homemade using PVC or metal hoops, or bought as mini tunnel kits. For many years, I made mini tunnels from ten-foot lengths of half-inch diameter PVC conduit to grow fresh vegetables in winter. These were bent over my four-foot wide beds and slipped over one-foot long rebar stakes for stability. The stakes are spaced three to four-feet apart on either side of the vegetable beds. However, in recent years, I’ve transitioned into using sturdy metal hoops for my mini tunnels. I have a hoop bender that turns metal conduit into perfect hoops in mere minutes. You can read more about how I bend metal hoops here. No metal bender? You can still use metal hoops by buying pre-bent hoops like these. Both PVC and metal mini tunnels are covered with a heavyweight row cover or a piece of greenhouse poly with the ends secured against the winter weather.
- Strawbale cold frames are a snap to build, and a great way to shelter taller growing crops, like leeks, kale, collards, and Brussel sprouts for winter harvesting. To make a strawbale cold frame to grow fresh vegetables in winter, surround your crops with a rectangle or square of strawbales in late autumn, topping it with a piece of polycarbonate or an old door or window. Winter harvest by lifting the top to reach the vegetables beneath. Another super easy cold frame is a portable structure, like this one, that can be moved over crops as needed.
- Mulch is perhaps the cheapest way to grow fresh vegetables in winter. It’s the perfect season extender for cold-season root crops like carrots, beets, and parsnips. In late autumn, before the ground freezes, cover the bed with a one to two foot thick layer of shredded leaves or straw and top with an old bed sheet or row cover to hold the insulation in place. To harvest, lift the fabric cover, push back the mulch, and dig your roots. You’ll find more information on mulching winter vegetables here.
- Quick cloches are perfect for protecting container vegetables or mature garden plants like kale. To make one, slip a tomato cage overtop your plant, or or surround it with three to four bamboo posts. Cover with a clear garbage bag securing the bottom with a bungee cord or twine. Depending on your region and the type of vegetable, you may not be able to harvest all winter, but this will extend the harvest by weeks or months. For smaller plants, you can use simple plastic cloches found at most garden centres or online.
2. Think greens! Salad greens are among the toughest of crops, with a wide variety thriving in the cool and cold seasons. Most salad greens need to be direct seeded about 4 to 6 weeks before the first expected fall frost, but gardeners with cold frames can get away with planting a little later. For winter harvesting, stick to the most cold tolerant greens like kale (try Prizm, a recent All-America Selections Winner), mizuna, mache, mustard, claytonia, spinach, endive, and arugula.
- Mizuna is a winter superstar in our cold frames with pretty, serrated leaves that can be green or purple, depending on which type you are growing. My favorite variety is Red Kingdom, a 2016 All-America Selections National Winner for its quick growth and vibrant color. Unlike peppery mustard, mizuna has a mild flavor that’s great in salads, wraps, and sandwiches.
- Mache is ridiculously easy to grow and is so cold tolerant in my zone 5 garden that it doesn’t need protection. However, with our snowfalls, I grow it in frames and mini tunnels so it’s quick and easy to harvest. The plants form tidy rosettes in the garden and we eat them raw in salads by slicing the small plants off at ground level. After a quick wash, they’re tossed with olive oil, lemon juice, and a sprinkle of salt and enjoyed in a simple, but sensational salad.
- Tatsoi is a must if you want to grow fresh vegetables in winter. Like mache, it grows in a rosette, but tatsoi forms larger plants, typically up to a foot across. Pick the individual, deep green, spoon-shaped leaves for salads or stir-fries, or harvest the whole plant when still small and sauté with garlic, ginger, sesame oil, and a splash of soy sauce.
In zones 5 and above, you can continue to harvest unprotected cold-tolerant leafy greens into December and January. But, in my region, we tend to get a lot of snow and unprotected crops – even the cold-tolerant ones – quickly get buried, making harvesting difficult. This is where protective devices like mini hoops and cold frames come in handy.
3. Overwinter. Overwintered crops are those that are planted in late summer or autumn, covered for winter, and harvested at the very end of winter and into early spring. It’s easy to stretch the harvest into early winter with row covers, cloches, and tunnels, but come March, those initial crops will be eaten or have succumbed to cold winter weather if they weren’t properly protected.
Overwintering allows you to harvest greens at time when most of us are beginning to sow tomato seeds for spring. Does that sound difficult? Nope! It’s actually very easy to overwinter cold-tolerant leafy vegetables. For example, in my garden, I typically seed a few raised beds with spinach in late September to early October. The bed is then covered with a mini hoop tunnel in mid-autumn, and forgotten about until mid-March. At that point, I pop open the end of the tunnel and peek inside; the bed is full of spinach waiting to be harvested.
If you’re not a spinach fan, there are other crops that can be overwintered with this technique. I recommend sticking to the most cold tolerant vegetables like kale, spinach, arugula, Asian greens, tatsoi, Yukina Savoy, and mache. You’ll find more tips on overwintering crops here.
Tell us about your garden; do you grow fresh vegetables in winter?