The days are getting shorter, the air colder. What can we do when we want to squeak out a few more weeks of growing?
A simple and fun way to grow vegetables year-round is to use a cold frame. Cold frames are easy to make and handy to use. Many gardeners stretch their growing seasons up to a month before and beyond the usual times, and some even grow throughout the winter. These helpful frames keep frost at bay, and also are useful to help acclimatize seedlings to the outdoors, starting plants early and to grow plants not usually found in your area. By using a cold frame, you can enjoy fresh vegetables such as lettuce, broccoli, cabbage, Brussels sprouts, turnips and carrots all through the year. Cold frames also protect the delicate seedlings and mature plants from animals and do not dry out as quickly as a regular garden.
A cold frame is a box-like structure with four walls to trap in any heat and protect the plants inside. It keeps the cold out, and the inside soil warm, so growing can continue even in bad weather. Its lid is transparent, so light can easily reach the plants. It can be made of anything, though usually from sturdy materials such as concrete or plywood. Hay is also suitable as it retains heat well. Using old windows as a lid works well, and they give the windows new life and purpose. Most gardeners use plexiglass or clear plastic sheets attached to a frame. Steer clear of using any wood treated with creosote or other chemicals as they can poison the garden by leaching into the ground.
Cold frames can be any size, so you can build to suit your lifestyle and yard. You can build the cold frame to be a permanent fixture in your yard, or you can build a temporary one which can be put away when you are finished with it. The lid commonly determines the dimensions of the structure. Frames larger than 2 by 4 feet are useful, but anything larger (say bigger than 3 by 6 feet), will make it difficult to reach the plants you are growing.
When building your own cold frame, make the back 4 to 6 inches higher than the front. This will create maximum light for the plants, as well as allowing water and snow to drain without a problem. Find a south-facing, sunny spot with good drainage and protection from the wind. It is also a good idea to set your garden up near a water source to save on time and energy. Before setting up the frame, first put in a layer of rough gravel. Next, put six inches of soil on top of the gravel; this creates drainage. You will want to keep the soil moist, but avoid letting it get soggy. There is such a thing as too much water.
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In your cold frame, you can grow plants in pots or right in the soil. It just depends on your preference. Remember to pay attention to the weather, or more importantly, the temperature. Inside your cold frame, the temperature should be below 75 degrees Fahrenheit for summer plants, and below 60 degrees Fahrenheit for spring and fall plants. If you need to cool the inside of the frame, simply lift the lid. If the temperature outside gets up to 40 degrees Fahrenheit, open the lid about six inches and place a block or stick to keep the lid open. Close the lid in the afternoon to keep heat in for the night as the air will cool down. If you want to make it easier, you can install an automatic venting device, and add a heating cable; it all depends on how serious you want to be with this project. Keep in mind as well, you may need to provide some sort of shade if things get too hot. It would be beneficial to place a thermometer in the cold frame to monitor temperature.
If the night is going to be uncommonly cold, your plants will need more protection than usual. Since more heat dissipates through the glass or plastic window, you can place blankets, hay, straw, even newspaper, on top to insulate the plants and keep the heat in. Heavy snow should be removed so the window doesn’t crack or break.
There are benefits to putting seeds directly into the ground of the cold frame. For example, if you find transplanting seedlings a hassle, this would eliminate any stress. When preparing seedlings for transplanting from the cold frame, leave the frame cracked open for a few days so the seedlings can adjust to the outside temperatures. It is best to plant your winter crop in August or September as the days are still long and sunny enough to start a proper germination. Otherwise, you can transplant seedlings grown indoors to the cold frame.
When using your cold frame for getting a head start on spring, plant seeds in the early spring at least six weeks before the last expected frost. This is a good time for lettuce, broccoli, kale and cabbage to be planted. Tomatoes and peppers should be planted four weeks before the last expected frost.
Cold frames are often called miniature greenhouses, and are wonderful places for children to learn about different plants and their care. They are also a great way to continue to enjoy fresh and chemical-free produce all throughout the year, enhancing a healthy lifestyle. Cold frames can also produce lovely flowers for display and gifts in any season.
When used for either food or flower, cold frames are a useful and fun way to include the whole family. Why not try one for a season and experience a gift that really keeps on giving, or growing, all year long?
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