Growing vegetables in the winter is really a matter of harvesting, not so much growing. The idea is to get the vegetables growing during the late summer and then harvest them during the winter by protecting them from exposure to the elements and denying them water. Water in the plant cells is what freezes and kills the plants, so watering must stop as frost starts to set in.
It's necessary to select cold hardy vegetables -- think kohlrabi, broccoli and cabbage -- the cruciferous vegetables. You can't grow or harvest summer vegetables like cucumbers, tomatoes, peppers and squash during the winter.
Winter Vegetables
Some of the most cold hardy vegetables are leek and kale. Many of the Asian greens like Bok Choi are also cold hardy.
Leek is a plant commonly used in soups and stews, and can be substituted for onion in many recipes. This type of plant offers us the stalk for consumption. The white lower portion of the stalk is often sliced across for nice "rounds" in a soup or it can be used much like an onion in stir fried vegetables and the like. Leeks can "winter over" in growing zones 4 and higher if given some protection.
Kale is a green, much like Swiss chard, mustard or turnip greens. We consume the leaves of the plant. It is used in soups, stews and prepared as a steamed green by itself. It's very cold hardy and can withstand frost and winter weather with little or no protection in zones 6 and higher. Given a little protection, Kale will survive in zones 4 during the winter.
I have harvested Bok Choi from my unheated greenhouse after minus 14 F. Lettuce can easily go below freezing, and radishes, turnips, peas, broccoli, Brussels sprouts and cabbage are also very cold tolerant.
Protection During the Winter
The basic resources necessary 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, a single cover is all that's necessary. In colder climates like zones 4 and lower, 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 give you much more room to work, and it keeps you out of the winter weather as well.
The clear plastic covering of a garden structure 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 very quickly.
Cold weather growing and harvesting of vegetables must be done at ground level, so the natural heat from the earth will be trapped by the layers of clear covering. That's one reason why root crops and other close to the ground vegetables are the best selection for winter gardening - they can easily be covered with a row cover or cold frame.
Think of each layer of plastic as a blanket. For cold weather use one blanket, for very cold weather use two.
Harvesting
Most of what you're going to do in the winter is harvest. Planting and growing are for the most part out of the question. You need to save that for spring.
As long as you haven't watered your plants during the winter, they should be in relatively decent shape for harvesting. The key is to allow them to warm up a bit before harvesting. Let them get well above freezing for at least a couple of hours before you attempt to harvest.
This might mean waiting a day or so in between harvests, but if you don't wait until it warms up under those "blankets," you'll be harvesting mush. Let the sun do its job and warm things up for a few hours before you start gathering your crispy crops from that life-size refrigerator.
It's necessary to select cold hardy vegetables -- think kohlrabi, broccoli and cabbage -- the cruciferous vegetables. You can't grow or harvest summer vegetables like cucumbers, tomatoes, peppers and squash during the winter.
Winter Vegetables
Some of the most cold hardy vegetables are leek and kale. Many of the Asian greens like Bok Choi are also cold hardy.
Leek is a plant commonly used in soups and stews, and can be substituted for onion in many recipes. This type of plant offers us the stalk for consumption. The white lower portion of the stalk is often sliced across for nice "rounds" in a soup or it can be used much like an onion in stir fried vegetables and the like. Leeks can "winter over" in growing zones 4 and higher if given some protection.
Kale is a green, much like Swiss chard, mustard or turnip greens. We consume the leaves of the plant. It is used in soups, stews and prepared as a steamed green by itself. It's very cold hardy and can withstand frost and winter weather with little or no protection in zones 6 and higher. Given a little protection, Kale will survive in zones 4 during the winter.
I have harvested Bok Choi from my unheated greenhouse after minus 14 F. Lettuce can easily go below freezing, and radishes, turnips, peas, broccoli, Brussels sprouts and cabbage are also very cold tolerant.
Protection During the Winter
The basic resources necessary 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, a single cover is all that's necessary. In colder climates like zones 4 and lower, 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 give you much more room to work, and it keeps you out of the winter weather as well.
The clear plastic covering of a garden structure 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 very quickly.
Cold weather growing and harvesting of vegetables must be done at ground level, so the natural heat from the earth will be trapped by the layers of clear covering. That's one reason why root crops and other close to the ground vegetables are the best selection for winter gardening - they can easily be covered with a row cover or cold frame.
Think of each layer of plastic as a blanket. For cold weather use one blanket, for very cold weather use two.
Harvesting
Most of what you're going to do in the winter is harvest. Planting and growing are for the most part out of the question. You need to save that for spring.
As long as you haven't watered your plants during the winter, they should be in relatively decent shape for harvesting. The key is to allow them to warm up a bit before harvesting. Let them get well above freezing for at least a couple of hours before you attempt to harvest.
This might mean waiting a day or so in between harvests, but if you don't wait until it warms up under those "blankets," you'll be harvesting mush. Let the sun do its job and warm things up for a few hours before you start gathering your crispy crops from that life-size refrigerator.
Clair Schwan is an experienced vegetable gardener year round. See how he accomplishes winter vegetable gardening with his homemade greenhouses. The key is to grow winter vegetables so you're not fighting nature.
Article Source: http://EzineArticles.com/?expert=Clair_Schwan 
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