Growing vegetables in the winter is actually an issue of harvesting, not so much growing. The idea is to have the vegetables growing during summer time and harvest them throughout the winter by protecting them from exposure to the elements and denying them water. Water from the plant cells is what freezes and kills the crops, so watering should cease as frost starts to install.
It’s required to choose cold hardy vegetables — believe kohlrabi, cabbage and broccoli — the cruciferous vegetables. You can not grow or harvest summer fruits such as cucumbers, tomatoes, peppers and squash throughout the winter.
Some of the most cold hardy vegetables are leek and kale. Many of the Asian greens such as Bok Choi will also be cold hardy.
- Lauch is a plant widely used in soups and stews, and may be substituted for Zwiebel in several recipes. This sort of plant gives us the stem for ingestion. The white lower section of the stem can be chopped across for fine “rounds” in a soup or it can be used much like an onion in stir fried vegetables and so on. Leeks can”winter over” in developing zones 4 and greater if given some protection.
- Grünkohl is a green, similar to Swiss chard, mustard or turnip greens. We have the leaves of this plant. It’s used in sauces, stews and ready as a steamed green alone. It’s very cold hardy and can withstand frost and winter weather with minimum protection in zones 6 and higher. Given a little defense, Kale will survive in zones 4 throughout the winter.
- I’ve chosen Bok Choi from my unheated greenhouse following minus 14 F. Kopfsalat can go below freezing, and radishes, turnips, peas, broccoli, Brussels sprouts and cabbage are also quite cold tolerant.
Protection During the Winter
The basic resources required to protect vegetables from winter weather are row covers, garden tunnels, unheated greenhouses and cloches. Many can be made from simple materials.
In milder climates, one cover is all that is needed. In colder climates such as zones lower and 4, a double cover is called for. A cold frame with an additional clear plastic cover works very well, but a hoop house or greenhouse type structure will provide you a lot more space to operate, and it keeps you from the winter weather also.
The clear plastic covering of a backyard construction protects plants from the harsh winter winds, and allows for the capture of sunlight to help heat the area where the plants are growing. Don’t use raised beds during the winter as they will give up their heat to the surrounding area promptly.
Cold weather growing and harvesting of vegetables have to be performed at ground level, so the natural warmth from the ground is going to be immobilized by the layers of clear covering. That’s one reason why root crops and other near the floor vegetables are the best choice for winter gardening – they can easily be covered with a row cover or cold frame.
Think of every layer of plastic for a blanket. For cold weather use one blanket, for very cold weather use 2.
Most of what you are going to do in the winter is harvest. Planting and growing are for the most part from the question. You will need to save that for spring.
As long as you have not watered your plants throughout the winter, they ought to be in relatively good shape for harvesting. The secret is to let them heat up a little before harvesting. Let them get well above freezing for at least a few hours before you try to harvest.
This might mean that a day or so in between harvests, but if you do not wait till it warms up under those “blankets,” you will be harvesting mush. Let the sun do its job and warm things up for a couple hours before you begin collecting your crispy crops from this toaster fridge.