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This article will show you how it is possible to garden year-round. You may not think it at first, but you can have fresh, healthy, produce even through the winter!
There are several ways to extend the season and keep your garden productive with hardy leafy greens and root crops surviving chilly weather.
You can employ essential techniques for preserving your crops through frost and low temperatures by doing the following:
- Use Low Tunnels to Extend Your Season
- Protect Your Winter Plants
- Select the Right Cool-Weather Crops
Use Low Tunnels to Extend Your Season
In the late 19th century and early 20th century, Parisian market gardeners continued to grow throughout the winter to keep tables in France stocked with fresh produce.
Without reliance on petroleum-based technology to fuel their growth, the French relied on green manures and animal manures to keep their crops warm during the winter. Horse manure, for instance, allowed them to continually fertilize their small plots for maximum efficiency. The gardens may be gone now, but you can still see the markets here.
Four-Season Gardening with Eliot Coleman
We have lost many of these techniques and tips for growing crops in winter conditions. Fortunately however, Eliot Coleman, a market gardener in Harborside, Maine, revived these organic farming methods in the 1990s. Since then, he has advocated for four-season growing and has inspired and motivated growers to extend their growing seasons.
After careful observation and experimentation, Eliot noticed that many winter vegetables were more sensitive to temperature changes than the seasonal reduction in the sun's irradiance (a measure of the sun's radiation, measured in watts per square meter).
By focusing on low-cost methods to raise the soil and air temperature, he was able to get two extra seasons of growing (fall and winter).
After experimenting with various solutions, he invented a two-layer low tunnel hoop house solution that is economical and easy to set up for your raised beds.
How to Build a Low Tunnel
- Purchase 1/2" aluminum electric conduit (usually comes in 10ft lengths).
- Bend each conduit to the desired arc using a bender tool.
- Use the conduits as ribbing and secure them in place.
- As the weather cools, add row cover or knitted shade cover over the ribbing (Use clips or snap clamps to secure the row cover)
- When the weather further cools, add transparent greenhouse film for the second layer of protection.
Overall, this method can keep the temperature inside the low tunnel about six degrees warmer than the outside weather, which in many cases is just enough to keep hardy vegetables from receiving frost damage.
You can read more about fall gardening protection here.
Protect Your Winter Plants
A cold frame consists of a box with a clear sloped lid, usually glass or plastic. The structure can be buried in the ground and collects the sun's heat during the day. A well-made cold frame can shift your USADA growing zone up by one zone. For example, if you are in Zone 6, the cold frame could allow you to grow like it is in Zone 7.
You may need to vent the air in the box on warm days during the winter.
An old technique involves placing a clear glass or plastic bowl with a wide lip over each plant. Seedlings and young plants get established better in this environment. A variation on this involves the container having walls filled with water. The water absorbs heat during the day and, even when frozen, protects the plants inside (think of an igloo)
These techniques help to insulate your crops from the cold weather, but they won't change the environment enough that you can grow summer-fruiting crops like tomatoes and melons.
Your choice of winter-hardy vegetables is key to ensuring that they can handle whatever the weather may be.
Select the Right Cool-Weather Crops
As far as annual vegetables go, leafy greens and root crops seem better to handle frost temperatures (below 32 degrees Fahrenheit). Here's a good selection of these crops:
A hardy form of cabbage that can establishes a deep enough root that it can survive
the lettuce family is quite broad, and there are many heirloom varieties (Artic King, Ice Queen, etc.) that are hardy down to freezing (and even then can survive the winter if their roots are established).
Mache is a nice hardy salad green that grows fast and tastes great for a change of pace.
A short, spreading green first found by miners looking for food during the 1849 California gold rush. It has a nice crunch similar to bean sprouts and is high in vitamin C.
There are a number of brassicas other than Kale that do well in cold weater (most brassicas prefer cooler weather to thrive). Collards are like big, loose cabbages. You can harvest Brussel Sprouts' leaves separate of their more well-know side shoots. And Tatsoi is very tasty in stir-fries (although I've found it not quite so hardy as the others).
Spinach is another hardy green vegetable. It's important to start this one earlier in the summer/fall to establish it well. I've noted that it doesn't grow much if you transfer the seedlings too late into the fall.
Farmers use alfafa, clover and winter peas typically more for "soil building." So I'm not including them on this list. I've also left out growing winter grains like barley and oats since it isn't practical to grow them in a suburban or urban garden.
Where regular peas start to die off around freezing temperatures, Fava beans are a bit more hardy and withstand temperatures down to 20 degrees. They also establish a deeper root system and more foliage than peas, so they can produce more green fertilizer. The only pain with Fava beans is that they require double shelling, which is time-consuming and as a fruiting crop, there are not going to be too many pollinators out and about until March at the earliest.
Carrots are a hardy biennial that actually grows sweeter as the winter weather sets in as they convert some of their starch into sugars to survive the cold temperatures. If you time your plantings correctly, you can pull up carrots the whole winter.
A relative of the carrot, parsnips require fresh seed to be viable, but they grow steadily during the winter months and rapidly increase in size during the early spring months. Like carrots, they taste sweeter in the winter months.
Beets grow slowly during the winter months. But you can harvest their leaves and use them during the winter in the same way as spinach and swiss chard. Because Beets grow greens so quickly, you can continuously harvest their leaves during the winter and pick the beetroots in the spring.
Many onions are also biennial, so plant them in the fall and harvest them in the spring/summer of the following year. Of particular interest for winter growing are leeks and garlic, which can handle most of the cold weather thrown at them without any problem.
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