Almost anyone can grow a great garden in the summertime. But what about harvesting crops in the middle of spring, when your neighbors are just beginning to turn over their own ground? Creating an early harvest is what can separate the superior gardener from the run of the mill. Cold frames are great for stretching your garden’s growing season at both ends. In the spring, cold frames proved a sheltered area for seed starting and to harden off transplants that were grown indoors.
During the fall, cold frames enable you to harvest fresh vegetables longer by protecting your plants from frost and cold temperatures.
Building a cold frame can be a simple as attaching a discarded window sash to a box shaped framework of wooden boards or by placing a window sash over a group of straw bales arranged to form a rectangular base. Instead of constructing a homemade cold frame, you can purchase commercial units made out of high tech materials that are designed to retain warmth and transmit sunlight to the plants growing inside.
Inexpensive models are available that are constructed with a plastic or metal tube frame that’s covered by a transparent, woven plastic fabric. This style of cold frame is lightweight, portable and can easily be moved from one section of the garden to another, making them ideal for use in raised beds.
The more expensive types of cold frames use an aluminum framing that’s covered with twin walled polycarbonate panels. These units are sturdier and provide better insulation, but are not as portable and usually remain in a permanent, fixed location outside of the garden.
Yet another type of cold frame is the plastic tunnel cold frame. There are four really great aspects to the plastic tunnel: 1) It is easy to build and is made of standard materials. 2) It is cheap. 3) It is fast to put up and take down. 4) It will keep your plants warm and it will keep them from getting too hot.
For growing fall gardens, plants can be sown directly in the fixed location cold frame during late summer. Winter vegetables that were planted in the garden beds can be covered with one of the portable style cold frames.
When it turns colder still, or in a colder Northern climate, even with the shelter of a cold frame, plant growth will slow or stop as temperatures drop below freezing. But the cold frame will enable you to continue growing and harvesting organic vegetables well beyond your normal growing season.
When spring returns, many of the vegetables that were planted in the cold frames the previous fall will resume growing to offer extra early fresh produce at a time that the garden’s beds are still frozen and inactive.
At the end of winter, the cold frame can be used as a nursery bed for starting seedlings of lettuce, kale, spinach and other leafy greens. Sow the seeds thickly and let them germinate and grow inside the cold frame until spring arrives. When outdoor conditions are suitable the seedlings can be thinned and transplanted from the cold frame into the garden’s raised beds.
Cold frames can also be used in the spring to harden off transplants, which were started indoors and grown under lights. Placing the flats or containers of transplants inside the cold frame will allow them to gradually adjust to the harsher growing conditions encountered outdoors, without the need to bring the plants back inside during the night.
Crops growing inside cold frames can survive with little or no watering or other attention during the winter months. But you will need to keep a close eye on the plants growing in cold frames during the fall, and especially during the spring to ensure that they receive enough moisture and to vent the cold frame to prevent plants from overheating on warm days.
The location of your cold frame is essential to success. On every piece of property, there is usually some far warmer area. This is the one you should seek out for your cold frame. But a good site alone will not allow most plants to survive cold nighttime temperatures. For that you must create this artificial environment that will allow your seeds to germinate and your plants to prosper.
In places as cold as upstate New York, they set up their cold frames as early as the second half of March. Wait for one of those unusually warm days that we sometimes get in this area at the end of the winter when it is a joy to be working outside. With all the materials on hand, and perhaps an extra set of hands attached to a friend, it is not beyond the realm of possibility to construct a plastic tunnel cold frame and plant an entire garden in a long afternoon.
There are two factors that can cause serious damage in the plastic tunnel cold frame garden that require constant vigilance. The first is damage from excessive heat. The tunnel is a marvelous seed germinator, but the heat so wonderful for germination is excessive once the seedlings have emerged. A cloudless day in the 70s can take the temperature inside the tunnel to 150 degrees, and the crops you have nursed through the fierce March weather will wilt, scorch, bake and finally perish in the April sun.
Think ventilation. When in doubt, ventilate. If you run to Medford for the day on any but the coldest days, ventilate. End ventilation is almost always sufficient with the plastic tunnel cold frame. A little cold wind on your plants will do small damage compared to excessive heat!
Now, I know I go on and on about “Feed your soil! Bring on the organic matter!” The second problem can arise from TOO MUCH organic matter in the garden. Many of us take pride in the lovely structure of our soil, but too often our compost is not quire as broken down as it should be. Including this kind of stuff, or worse yet – manure, in a plastic tunnel garden is dooming it to failure! Fungi thrive in this kind of environment. The result will be rampant damping off and other diseases. Keep your plastic tunnels and cold frames a little more spare on organic content than an open-air garden. If there is any sign of weakness in the soil, you can always add a boost with some liquid fertilizer, like fish or seaweed emulsion.
The day you plant your garden in the tunnel, water it heavily and seal it shut. No more watering is required until the seeds have germinated. After that, watering depends on the temperature, how robust your seedlings have become and the amount of ventilation you are using. With no ventilation, your system is a closed one and should require almost no additional irrigation. The moment you ventilate, you will have to water in order to supply the rapidly growing plants with the moisture they need.
“This is all fine and wonderful,” you say, “but what exactly am I supposed to grow in this weird tunnel thing?” Ah. You will select those crops that most appeal to you and that suit the particular conditions found under plastic. You will want to plant very intensively, as in French intensive gardening. This technique measures its success by what percentage of the entire bed is completely covered with foliage at each moment of the season. Call it “The Art of Plentitude.”
Your initial planting should comprise crops that can take some cool weather; mostly various kinds of greens for cooking or eating in salads. The second planting is the seeds of warm-weather crops and next one is seedlings of warm-weather crops. Peas, onions and potatoes are not suitable for the tunnel or frame, but should instead be placed directly in the regular garden.
You will find that your first planting of greens to be a real blessing after a cold winter! Be sure to plant some particularly fast-growing things so you can amaze your friends and family (and even yourself!) with garden food with the snow barely off the ground. Garden cress seems to sprout the minute the seeds hit the ground and is a standard which will prove to be the first and fastest harvest from the cold frame garden – ready to eat in a couple of weeks. Next come radishes, which you can broadcast thickly, thinning some of the greens for immediate consumption. Then your lettuces. Broadcast early in the cold frame with a mixture of early season, mid-season and late season. Thin them severely and leave some head lettuce to carry you through most of the late summer. There is the “mesclun mix”, also known as “yuppie greens” that you can frequently harvest by cutting back with a scissors. And – finally – plant a lot of spinach. It’s insanely good for you on many, many levels and is deliciously succulent when grown under plastic.
When things warm up a bit, start your warm season crops from seed. At one end of your tunnel, start your zucchini, crooknecks or patty pan and on the other, your cucumbers. We’ve come to really like those small, round lemon cucumbers as well as the long, light colored Armenians. As they grow, you pretty much pick and eat all of their competition. When the plastic is removed from the frame, the huge squash plants hang way outside the frames. At the other end, train your cucumbers to a six-foot netted trellis, which uses very little planting space. As the cucumbers grow towards the sky, they give a harvest much more bountiful than when allowed to lie on the ground.
Cold frames come in really handy for tomatoes and peppers. You can actually set out plants here in the Rogue Valley six to eight weeks earlier than you would otherwise! Set out your tomato plants between rows of greens and harvest those greens as they compete with the tomatoes. Support those tomatoes on six-foot high wooden trellises and prune them rather severely! The partial shade made by the trellis is actually appreciated by the lettuces and other greens sharing that space once the sweltering days of July arrive and they are thinking of going to seed, which – in my mind is nothing short of betrayal.
Take your tunnel down around June 1 when all danger of frost is past and the plants want more room anyway. Hose down the plastic, let it air dry and roll it up into a black plastic garbage bag, to be stored for the following year. The frames for the tunnel can be left up indefinitely.
Cold frames have been around for just ages. The ones I have described here are cheap and convenient. Use a cold frame or tunnel for just one year and it is unlikely you will ever want to garden again without it.
During the fall, cold frames enable you to harvest fresh vegetables longer by protecting your plants from frost and cold temperatures.
Building a cold frame can be a simple as attaching a discarded window sash to a box shaped framework of wooden boards or by placing a window sash over a group of straw bales arranged to form a rectangular base. Instead of constructing a homemade cold frame, you can purchase commercial units made out of high tech materials that are designed to retain warmth and transmit sunlight to the plants growing inside.
Inexpensive models are available that are constructed with a plastic or metal tube frame that’s covered by a transparent, woven plastic fabric. This style of cold frame is lightweight, portable and can easily be moved from one section of the garden to another, making them ideal for use in raised beds.
The more expensive types of cold frames use an aluminum framing that’s covered with twin walled polycarbonate panels. These units are sturdier and provide better insulation, but are not as portable and usually remain in a permanent, fixed location outside of the garden.
Yet another type of cold frame is the plastic tunnel cold frame. There are four really great aspects to the plastic tunnel: 1) It is easy to build and is made of standard materials. 2) It is cheap. 3) It is fast to put up and take down. 4) It will keep your plants warm and it will keep them from getting too hot.
For growing fall gardens, plants can be sown directly in the fixed location cold frame during late summer. Winter vegetables that were planted in the garden beds can be covered with one of the portable style cold frames.
When it turns colder still, or in a colder Northern climate, even with the shelter of a cold frame, plant growth will slow or stop as temperatures drop below freezing. But the cold frame will enable you to continue growing and harvesting organic vegetables well beyond your normal growing season.
When spring returns, many of the vegetables that were planted in the cold frames the previous fall will resume growing to offer extra early fresh produce at a time that the garden’s beds are still frozen and inactive.
At the end of winter, the cold frame can be used as a nursery bed for starting seedlings of lettuce, kale, spinach and other leafy greens. Sow the seeds thickly and let them germinate and grow inside the cold frame until spring arrives. When outdoor conditions are suitable the seedlings can be thinned and transplanted from the cold frame into the garden’s raised beds.
Cold frames can also be used in the spring to harden off transplants, which were started indoors and grown under lights. Placing the flats or containers of transplants inside the cold frame will allow them to gradually adjust to the harsher growing conditions encountered outdoors, without the need to bring the plants back inside during the night.
Crops growing inside cold frames can survive with little or no watering or other attention during the winter months. But you will need to keep a close eye on the plants growing in cold frames during the fall, and especially during the spring to ensure that they receive enough moisture and to vent the cold frame to prevent plants from overheating on warm days.
The location of your cold frame is essential to success. On every piece of property, there is usually some far warmer area. This is the one you should seek out for your cold frame. But a good site alone will not allow most plants to survive cold nighttime temperatures. For that you must create this artificial environment that will allow your seeds to germinate and your plants to prosper.
In places as cold as upstate New York, they set up their cold frames as early as the second half of March. Wait for one of those unusually warm days that we sometimes get in this area at the end of the winter when it is a joy to be working outside. With all the materials on hand, and perhaps an extra set of hands attached to a friend, it is not beyond the realm of possibility to construct a plastic tunnel cold frame and plant an entire garden in a long afternoon.
There are two factors that can cause serious damage in the plastic tunnel cold frame garden that require constant vigilance. The first is damage from excessive heat. The tunnel is a marvelous seed germinator, but the heat so wonderful for germination is excessive once the seedlings have emerged. A cloudless day in the 70s can take the temperature inside the tunnel to 150 degrees, and the crops you have nursed through the fierce March weather will wilt, scorch, bake and finally perish in the April sun.
Think ventilation. When in doubt, ventilate. If you run to Medford for the day on any but the coldest days, ventilate. End ventilation is almost always sufficient with the plastic tunnel cold frame. A little cold wind on your plants will do small damage compared to excessive heat!
Now, I know I go on and on about “Feed your soil! Bring on the organic matter!” The second problem can arise from TOO MUCH organic matter in the garden. Many of us take pride in the lovely structure of our soil, but too often our compost is not quire as broken down as it should be. Including this kind of stuff, or worse yet – manure, in a plastic tunnel garden is dooming it to failure! Fungi thrive in this kind of environment. The result will be rampant damping off and other diseases. Keep your plastic tunnels and cold frames a little more spare on organic content than an open-air garden. If there is any sign of weakness in the soil, you can always add a boost with some liquid fertilizer, like fish or seaweed emulsion.
The day you plant your garden in the tunnel, water it heavily and seal it shut. No more watering is required until the seeds have germinated. After that, watering depends on the temperature, how robust your seedlings have become and the amount of ventilation you are using. With no ventilation, your system is a closed one and should require almost no additional irrigation. The moment you ventilate, you will have to water in order to supply the rapidly growing plants with the moisture they need.
“This is all fine and wonderful,” you say, “but what exactly am I supposed to grow in this weird tunnel thing?” Ah. You will select those crops that most appeal to you and that suit the particular conditions found under plastic. You will want to plant very intensively, as in French intensive gardening. This technique measures its success by what percentage of the entire bed is completely covered with foliage at each moment of the season. Call it “The Art of Plentitude.”
Your initial planting should comprise crops that can take some cool weather; mostly various kinds of greens for cooking or eating in salads. The second planting is the seeds of warm-weather crops and next one is seedlings of warm-weather crops. Peas, onions and potatoes are not suitable for the tunnel or frame, but should instead be placed directly in the regular garden.
You will find that your first planting of greens to be a real blessing after a cold winter! Be sure to plant some particularly fast-growing things so you can amaze your friends and family (and even yourself!) with garden food with the snow barely off the ground. Garden cress seems to sprout the minute the seeds hit the ground and is a standard which will prove to be the first and fastest harvest from the cold frame garden – ready to eat in a couple of weeks. Next come radishes, which you can broadcast thickly, thinning some of the greens for immediate consumption. Then your lettuces. Broadcast early in the cold frame with a mixture of early season, mid-season and late season. Thin them severely and leave some head lettuce to carry you through most of the late summer. There is the “mesclun mix”, also known as “yuppie greens” that you can frequently harvest by cutting back with a scissors. And – finally – plant a lot of spinach. It’s insanely good for you on many, many levels and is deliciously succulent when grown under plastic.
When things warm up a bit, start your warm season crops from seed. At one end of your tunnel, start your zucchini, crooknecks or patty pan and on the other, your cucumbers. We’ve come to really like those small, round lemon cucumbers as well as the long, light colored Armenians. As they grow, you pretty much pick and eat all of their competition. When the plastic is removed from the frame, the huge squash plants hang way outside the frames. At the other end, train your cucumbers to a six-foot netted trellis, which uses very little planting space. As the cucumbers grow towards the sky, they give a harvest much more bountiful than when allowed to lie on the ground.
Cold frames come in really handy for tomatoes and peppers. You can actually set out plants here in the Rogue Valley six to eight weeks earlier than you would otherwise! Set out your tomato plants between rows of greens and harvest those greens as they compete with the tomatoes. Support those tomatoes on six-foot high wooden trellises and prune them rather severely! The partial shade made by the trellis is actually appreciated by the lettuces and other greens sharing that space once the sweltering days of July arrive and they are thinking of going to seed, which – in my mind is nothing short of betrayal.
Take your tunnel down around June 1 when all danger of frost is past and the plants want more room anyway. Hose down the plastic, let it air dry and roll it up into a black plastic garbage bag, to be stored for the following year. The frames for the tunnel can be left up indefinitely.
Cold frames have been around for just ages. The ones I have described here are cheap and convenient. Use a cold frame or tunnel for just one year and it is unlikely you will ever want to garden again without it.
If you would like to have some plans for simple cold frames or plastic tunnels, please email thegardengrrl@gmail.com.
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