Cold frames have been used for hundred of years to extend food growing into the colder parts of the year. The Romans used cold frames of straw or stone and used sheets of mica for lids. A greenhouse may be heated, but a cold frame typically warms up only with the sun. If you end up in a situation where you need to rely more heavily on the food that you can grow yourself, cold frames allow you to harvest more food into the winter when you would normally have to rely on food you were able to story during the summer and fall.
This article from Off Grid Survival gives you an overview the cold frame and how to make some – Cold, Hard, Survival: Why Cold Frames Are Essential for SHTF Food Gardens.
Toward the end of summer or early fall, it may seem too early to start thinking about winter. And it may be too late to start thinking about a solid harvest. But when it comes to survival, you’ll need to consider the importance of surviving through winter and what you can do now to survive long-term.
Sure, hunting or fishing might get you by if you’re skilled enough. And food stores might help to supplement any fresh kill or frozen meats. But the real challenge is providing yourself and your family with access to fresh food in the dead of winter that can not only get you through winter, but also springboard your garden next summer.
This is where the cold frame comes in.
What is a Cold Frame?
For the purposes of gardening, a cold frame is a transparent-roofed enclosure that is used to protect plants from cold weather. The transparent top of the enclosures allows sunlight into the box while preventing heat from escaping.
This simple device is a proven method for growing fresh food through winter and priming summer gardens earlier than weather permits. They take less space than a traditional garden, require less maintenance, and have the potential to provide far more food than the empty produce section at a supermarket.
The Benefits of Cold Frame Gardening and Food Growing
Cold frames are essential in every long-term survival skill set. These simple, yet effective exoskeletons help to extend the harvest timeline well beyond the first frost of the year. This means an early or late winter doesn’t impact your food supply as much as it does other people. During times when food is scarce and access is limited, a cold frame can provide fresh produce essential to survival. Valuable spices and herbs aid in adding flavor to otherwise bland foods. They can be dehydrated or serve as barter items. Plus, you and your family can have access to natural fiber, vitamins, and minerals essential to a healthy diet.
Cold frames help to promote an early growing period. Regions that have late frosts have to delay planting much longer, which creates a much shorter growing season. But with cold frames, starts can begin much earlier without the need for a giant greenhouse. Transplants from a cold frame have a greater potential to produce than if you were to wait until the last freeze of the year.
Beyond the dangers of early or late frosts, some of the benefits of a cold frame include less stress on plants, protection from wind, less erosion, fewer weeds, and easy access. If properly oriented and built with care, these units can keep plants alive longer, allow sowing sooner, and generate food during the darkest days…
The frame itself is dirt simple. The concept centers around retaining heat in the soil to allow plants to grow despite snow, frost, or even frozen ground nearby. Frames retain heat by absorbing sunlight in an enclosed space, much like a greenhouse. It can be as basic as a 2-liter bottle over a plant, or as complex as a conservatory. The most effective form for small-scale home gardens is a rectangular box about 2’ wide by 3-4’ long.
To create a cold frame, first locate a piece of un-tinted, single-pane glass such as an old wooden window or aluminum storm window. Anything before the era of vinyl windows will work well. Double-paned windows often contain Argonne gas or tinting that may interfere with natural sunlight, heat gain, or heat loss. If you’re handy in the shop, you may be able to build your frame out of wood and order up the glass to fit from a glass shop in your area. Clear corrugated plastic also serves the same purpose – let light in and keep the cold out.
If you are looking for something that will hold up better than glass, I suggest cheking out Lexan — this stuff can be shot with a .22lr bullet and not break!
The glass, Lexan, or clear plastic goes on top of an exterior framework. The framework consists of a simple, low-profile box that can be made of 2X6 studs or even plywood. Wood is joined and secured at the corners to provide a box that rests directly on the ground. Just remember – the thicker the wood, the better the insulation will be. Alternatives to wood frames might include brick, foam, or insulated metal siding. Regardless of the materials used to create the framework, you’ll want to build it to match the size of the window or glass frame you intend to use. You may be able to add hinges to lift the glass for access or install a repurposed sliding glass window.
You should have a rectangle of wood framework with a glass panel or frame on top that can be lifted or opened for access. Now, orient the glass to where the longest side runs parallel to the equator. You want to capture as much sunlight as possible and if snow or rainwater is an issue, adding a slope to the frame will make snow removal and access much easier. The orientation and a good slope will garner the best results possible.
Once the frame is built, oriented and set in place on the ground, you can remove dirt a few inches down and either direct-sow your plants or provide a layer of compost to help get the seedlings started. By starting in late summer or early fall, you’ll have better luck with a regular harvest in mid-winter. By sowing in late winter or early spring, you’ll have heartier plants to transplant into your survival garden during summer.
If extreme temperatures or limited sunlight prevents the cold frame from heating up, you can add a light, heat tape, a heating mat, or additional insulation around the frame to aid in heat retention. Zones 1 through 5 will likely need more insulation and lighting than zones 6-10. Additional insulation can be obtained through foam, additional wood, or even organic insulation like grass clippings or seedless yard waste.
Unlike a greenhouse, a cold frame allows for a heightened level of discretion. The low-profile design is easy to disguise with shrubs or debris to prevent theft in times of chaos. This means that even in an urban setting, with limited space and relatively high visibility, you could still maintain a solid level of security and still have access to fresh food…
Fine Gardening: Easy to Build Cold Frame
Gardener’s Path: 10 of the Best DIY Greenhouses and Cold Frames for Your Backyard
The Self Sufficient Living: 10 Easy DIY Cold Frame Plans to Extend the Growing Season
Tenth Acre Farm: Protect Cold Weather Crops with a Cold Frame