How to Build a Cold Frame – REGENERATIVE.com

How to Build a Cold Frame

On a permaculture plot, the gardener is always looking for ways to maximize yield. There are many ways of trying to achieve this, including interplanting different species to fit more plants into a space, and choosing native species which are adapted to the local climate, so are more likely to thrive and produce an abundant crop.

One of the key factors in determining what will grow and how well it will grow in a site is the climate. In the early stages of making a permaculture design, analysis of the climate – from patterns of rainfall and drought, to winds, temperature and frost – is central to deciding what to plant where.

However, a permaculture gardener can also use a variety of techniques to improve or lessen the impact of climate and weather conditions, often prolonging the growing season for fruiting crops, thus maximizing yield. Techniques include using plants and manmade structures to influence microclimates, starting seeds indoors or in a greenhouse so they have a ‘head start’ when they are planted out in the garden, and mulching to prevent the soil temperature falling too far. Another method of prolonging the growing season is to use a cold frame.

Essentially, a cold frame acts like a miniature greenhouse. It has four walls that enclose plants, and a transparent lid that allows sunlight to enter. The structure serves to protect the plants from the worst of the weather – such as snow, frost and wind – and traps heat from the sun, making the temperature inside the cold frame significantly higher than the surrounding air. This can serve to extend the growing season by as much as a month either end, meaning you can get more crops. In some more temperate climates, a cold frame may enable you to grow plants throughout the winter that would not normally survive the cooler temperatures. You can either establish a permanent cold frame, or make one that you can move and store during the warmer weather. You can purchase prefabricated cold frames, but constructing one yourself is very easy and can be done with recycled and repurposed materials.

Siting
The ideal position for a cold frame is a south facing location that receives full sun. By facing south, the frame will get the maximum amount of sunshine during the day. It is also advisable to site the cold frame adjacent to a building or other large structure to protect it from strong winds, which will cause the temperature to lower.

Gather Materials
While you can purchase a cold frame completed readymade, or indeed buy the constituent parts new and construct it yourself, the greenest and most cost-effective method is to source discarded materials and work with those. The main thing you are looking for is an old window with the glass intact. This will form the lid of the cold frame. You want to avoid frames that have been treated with lead-based paint. If you cannot find a window frame that still has the glass attached, or you are in a climate where the glass is unlikely to withstand the extremes of weather (for instance, in areas that get heavy snowfall, the glass may not hold up against the weight of the snow) you could salvage some plastic or fibreglass and stretch that across the frame. If you can’t find even the frame, you can easily construct a lid from some old lengths of wood and cover with the plastic. Besides the lid, you will also need something with which to make the rectangular frame that encloses the plants and supports the lid. This is usually wooden boards but could be old bricks or breezeblocks. If using lumber, try to source untreated wood so you are not introducing any chemicals to the site.

Sizing
You could in theory, make a cold frame as large as you like, depending on the suitability of the site and the size of the materials you have sourced, but a standard size is a rectangle that is 3 feet wide and six feet long. This allows the gardener to reach all parts of the bed inside to harvest the crops, and is likely to work in conjunction with a recycled window (or two, depending on the size).

Slope
You want the cold frame to be higher at the back than at the front, so the lid is sloping. This has two advantages: firstly, it allows more sunlight to reach the plants inside, and secondly it means that rain and snow will drain off the cold frame. So if you are using boards to make the frame, cut the front one so it is shallower than the back, and cut the side boards at an angle. If using bricks or blocks, simply add an extra layer to the back wall.

Construction
Construct a frame from the boards or the other material you are using. Lay the lid over the frame. If you wish, you can add hinges to the photodune-4187952-winter-crop-on-a-field-sback of the lid to make lifting it easier, but you can simply lay it on top and remove it completely when you want to access the plants inside. If you wish, you can add insulation to the insides of the frame walls.

Tips
If using concrete blocks, consider painting them (with a non lead-based paint) black to absorb more heat. Piling soil, leaves, woodchips or straw around the outside of the frame will help to insulate it. You can also up the temperature inside the cold frame by adding fresh manure under a layer of soil, or simply placing a bowl of water inside. Water absorbs more heat than the ground and releases it more slowly, so will add heat during the night. Be aware that even though the idea behind the cold frame is to trap heat, on very sunny days (even those during winter) it can get so hot inside that the plants become damaged, so check the cold frame regularly and, if necessary, open the lid to vent some hot air, or provide some shade to protect it from the highest temperatures.

44 comments

This looks like a green house to me. I plant in a cold frame every year. A coupe of landscape timbers and an old patio door.

Yep, its a greenhouse, but glad for the instructions about building the cold frame…

would love one

My dad raised lettuce and radishes in cold frames way back in the 1930s.

MARLENE LOOK AT THIS

Absolutely!

this is so beautiful .

I grow kale and spinach all winter in a cold frame in bowling green, ky.

It’s a pain in the ass!

have you ever seen the book Four Season Gardening ? I think that’s what it’s called – AWESOME ideas for 4 season growing – cold frames within hoophouses – one of my fav garden books

NRCS has a cost-share program for a seasonal high tunnel like the one Eliot Coleman is shown in above in Cynthia’s post. We have a 30×72 that ran close to 6,000 dollars for the kit required by the study. If you want a lower-cost option that you can build on your own out of wood, Dr. Khan from Tuskegee University has designed one that can be built for 2500.00. The 6mil UV protected poly film covering is only good for about 4 seasons, but other than that the ongoing expenses are minimal, and because it’s considered a temporary structure one usually isn’t required to have a building permit. For a simple cold frame, stack bales of straw and lay a window on top of the opening. A stick can prop up the lid during the day and some christmas lights can be used to keep it warmer inside at night. Use the straw as mulch come spring. Keep growing!

I made one out of old windows and 2x4s and a few hinges. I dug the ground out and put in compost, and attached it to the side of the garage. I started my seedlings there while it was still frosting out.

I don t Knows where You guys live but its 25 below zéro today everything would freeze ,

It’s not 25 below underground! Passive solar is a great alternative to 4 season gardening too!

I used fresh cow manure which I put down on the bottom of the cold frame floor about 21/2 ft below, then added soil and then sand on top. This created a lot of heat as it composted over the winter turning my cold frame into a hot frame. I had another cold frame beside it made in the usual way to move my baby plants into to harden off in the spring. It worked beautifully for many years but I sold my property and studiedly live in a strata townhouse now. Miss those days with the huge garden, chickens, a couple pigs and only had a mclarys cookstove( wood stove) for heat and cooking.

I’m going to have a complete 28 window set of aluminum triple track glass storm windows removed from our house to be replaced after an exterior painting project with much more efficient and tightly sealed modern double track high wfficiency storm windows. Reserve the old windows now for your field…

there are all kinds of books on the subject at your local library…or you can contact your local extension office for tons of information…or you can go to the flower show in Madison-Feb13-15…or ask your Mom and I to pick up info when we go to the flower show…:]

Im learning lots of things from my friends who grew up in the 30s.

Yes one successfully one not

this is beautiful I wish I liked to fool with these but just cant do it

Beren Hollins

Kerry Ratcliffe

Thanks Steve! I love when my friends know me so well they show me this stuff!

It is not about today Beaulieu Jacqueline , it is about extending the season , I live in the Yukon and here a coldframe extends the season by about three to four weeks !

Katya Keen..reminded me of your project on the island

Can do it with bales of hay cubed. Then add old glass storm door on top. r

Jenny you and my son both “liked” the same Permaculture!!

I live in the city and my husband and I grow almost the entirety of our fresh food in our backyard with cold frames for winter. It must take these people ages to water and tend to this space. I would definitely not recommend this system, but good on them for growing their own food.

Love my cold frames could grow all year round in mine Little bit of supplumental lighting owered by solar Main garden has 6 frames 3ft wide by 20 ft long covered with polytunnel 3ft deap Massive 16ftby 16ft composts to feed them 7 types of worms

Esquimalt bc canada

You all have so much more cold to deal with. This is the first time that I don’t have much overwintering in the back yard in Victoria. We usually plant some lettuce in August and pick at it all winter. Always kale and we do have some in the front yard right now. We just built a new lasagne garden to fit our cold frame now we can rotate it over three different beds for the tomatoes and Basil, my main focus. We get late blight here so no cover no tomatoes. Thanks for the link.

My neice is a Permaculture Instructor!!

Elba Castillo esta es una idea para tu jardin…..

This looks like alot of fun!!

Where do you live?? I’d love a couple!

I believe this grant requires 3 years of in ground growing, then you can do whatever you want with the high tunnel. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/programs/financial/eqip/?cid=nrcseprd1342638

Danielle Louise x

Not sure if this posted already or in another group but you can get a grant for a cold frame if you grow in ground 3 years. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/programs/financial/eqip/?cid=nrcseprd1342638

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