Winter Gardening

We all love fresh items from the garden. It is a bundle of goodness to bring in a fresh harvest for immediate consumption. I don't think everything we eat needs to be raw, but I do think our food should be as fresh as possible. I love cutting a zucchini or yellow squash, and seeing the beads of fluid bulging out from the cut edge. That is healthy eating fresh from the garden!

We love our 3 season harvest, but how do we get a harvest from that elusive 4th season? Garden plants generally will not tolerate the mistreatment of winter. Some plants do not do well in cold tempratures, and most will die if frozen. We live in the northern USA, so we have cold winter weather with plenty of snow. The further north, the less the total hours of sunlight possible in the winter months. Available sunlight is further limited by winter cloudy weather.

I would like to explore options for growing fresh produce during the winter.

1. You can grow crops more cold tolerant.
2. You can insulate from the cold.
3. You can add heat to the plant environment.
4. You can start plants in the fall to give them a head start for winter harvest.

To be successful with winter gardening, I think the best plan is to try not to fight nature. Change the crops you grow to those most friendly to cold weather. Use covers as your insulation, and as a last resort, add heat. Many winter growers plan on no added heat to their growing areas, and if you start with this as your plan, it will be much easier to make good plant variety choices, and good practices. Heating a growing space can require a LOT of heat, so consider this carefully before you decide to heat a space. Also note, that any system you use will be fragile. If you depend on heat, then it only takes a few hours of failure to freeze the crop. Several people I know heat their greenhouses with wood, and all through the winter they get up in the middle of the night, and stoke the fire in the greenhouse. They were painfully aware of how demanding this is on your schedule and vacation options. Also remember the quantity of wood that will be required for such an endeavor.


What to plant?

If you want to focus on plants that are cold hardy, consider these:

• Arugula                   15 F / -9 C
• Beets                        20 F / -7 C
• Broccoli                   25 F / -4 C
• Brussel sprouts         0 F / -16 C
• Cabbage                   5 F / -14 C
• Carrot                      15 F / -9 C
• Cauliflower              25 F / -4 C
• Chard                       20 F / -7 C
• Clattonia (miners l)  10 F / -12 C
• Chinese cabbage      15 F / -9 C
• Collard                     10 F / -12 C
• Corn salad                 8 F / -13 C
• Endive                       5 F / -15 C
• Favas                         10 F / -12 C
• Kale                           8 F / -13 C
• Kohlrabi                     15 F / -9 C
• Garlic                         8 F / -13 C
• Leek                           8 F / -13 C
• Lettuce                       24 F / -4 C
• Minutina                    15 F / -9 C
• Mustard greens          15 F / -9 C
• Parsnip                       8 F / -13 C
• Rutabaga                    15 F / -9 C
• Spinach                      8 F / -13 C
• Turnip                        15 F / -9 C

We enjoy kale year round, even in terribly cold temps. We have kale all summer, and it stays strong during the fall. In winter the kale crowns collect a cap of snow and with this very minimal protection, we can collect kale all through the winter. It is a model hardy winter garden plant. It seems to freeze solid, and during a warm spell, it thaws and continues growing. If it does not have a snow cap, the crown could be desiccated and die. In my experience, drying out is more damaging than cold temperatures. We suggest a large fall crop of kale, as our chickens love the greens all through the winter, when there are fewer other greens to offer them.

Lettuce is another hardy winter plant. I have seen it freeze stiff, but with a little warmth it will gently thaw and continue to live. Harvest the greens when thawed if you want to use them as salad greens. If you pick them frozen they will be wilted when they thaw. Again, some minimal covering on your winter garden will prevent your plants from desiccating. Freezing may be tolerated, but not freeze drying.

Another crop we have had good winter success is broccoli. The leaf tissue can be burned with a hard freeze, but the plant withstands light freezing very well. I suggest you plan your crop harvest for early to mid winter, and with the cold temps, the crop should hold quite well.

Cauliflower is another brassica that will do well in winter. Tie the topmost leaves to shade and cover the head to keep it white.

Winter gardening is even better!

I find the brassicas do even better in the cold weather than in the summer. Additional benefits to winter gardening according to Eliot Coleman are:

1. Reduced pest problems
2. Reduced disease problems
3. Less need to water
4. Lower weed pressure

Another factor in favor of winter gardening is that many of the root crops convert some of their storage starch to sugars, as this helps raise their freezing tolerance. A wonderful side benefit for the gardener is the food becomes sweeter. I have noted that many of the crops that do well in the winter do not ship well. If you want some quality kale in the winter, you will need to grow it yourself.

Green house

With a simple plastic layer cover, we have seen temperatures moderated. Some consider each layer of plastic comparable to land 500 miles south. The University of Michigan has demonstration green houses using high tunnels, and a floating row covers (2 layers) and they are able to have beautiful cold season crops all winter long with no addition of heat. Remember the temperatures listed above. You do not have to keep the plants warm, you just have to mitigate the harshest of the cold lows. A friend local to us grows greens all winter with minimal heat using a single layer plastic high tunnel green house.

When to plant?

Most all seeds require some warmth to germinate well. I suggest starting the plants in the fall, and get a good size root and plant developed before the winter cold hits. The plants will not grow when the temperatures are close to or below freezing. Depending on your area, and your targets for harvest, you will want to adjust your schedule. Many suggest July or early August for a fall / winter crop.


Sprouts in a jar, all year long

We find alfalfa sprouts in a quart jar will germinate in our kitchen window any time of the year. Winter seems even better for sprouts than summer, as we have less spoilage of the older sprouts. Take 1.5 Tablespoons of seeds, and soak in a cup of water in a quart glass jar. After the seeds soak well, perhaps 8 - 12 hours, drain off the water, and set the sprouts jar on a window sil. We rinse / hydrate the sprouts twice a day. They will sprout in a day or so, and will be ready to eat in 4-6 days. Depending on how many you can incorporate into your diet, you can progressively start the jars to have a constant supply of healthy sprouts. Microgreens are plants just beyond the sprouts stage, say around 2 inches tall.


How-to ideas:

• Indoor planters before southern exposure windows.
• Planters such as 5 gal buckets, stored under a sheet of plastic, with a heat light in a protected space, such as a barn or garage.
• Greenhouse using plastic or glass as an insulation covering.
• Use a second row cover within the greenhouse, offering 2 layers of insulation.
• I am interested in earth-air tubes, which takes heat from the deep ground when air is blown through it. Air could enter the tube at a frigid 10 degrees, and exit unto the greenhouse at 47 degrees (or your local deep earth temperature).
• I have seen 55 gal barrels of water used in green houses as a back wall growing stand. Water has a very high specific heat, meaning it stores heat well, and can slowly release this stored heat through the night into a greenhouse environment.
• A friend of mine is interested in developing plans and statistics for green houses sunk into the ground around 4 feet, and adding insulation to the southern side of the green house.

Since we like to eat year round, I think we should get some good experience growing food year round as well. What experiences do you have to share?


Resources

• Food Saftey with Sprouts (pdf)