Keeping out the cold!

Welcome back to a belated episode of Lost in the Farmer’s Market, As this post was intended for last week some editing has been done to shorten the entire thing and you the reader will get two episodes this week. For note no market information will be in this post, only the straight facts about cold frames. The GMO-Hybrid-Open Pollenated topic will be covered in this week’s normal post and will include the market information for this weekends (Feb 1) farmer’s market. Without any further delay we present this week’s topic.

The cold frame is a simplistic device used in gardening, though the models as seen through seed catalogs and garden suppliers has made things a bit confused because their models often make interesting claims.  For reference a cold frame is essentially defined as an auxiliary structure typically used in tandem with or as a supporting element for a greenhouse. Cold frames often take form as a low structure typically no taller than three feet that bears a transparent roof that is removable or that can be raised on hinges to allow access. The purpose of a cold frame is to protect plants from adverse weather (cold or wet) and provide additional growing space allowing for an earlier or later growing season. In some cases cold frames are used for storage of dormant potted plants such as amaryllis, tulips and certain types or root vegetable.  Typically a cold frame is not heated, and thus its heated version is appropriately called a ‘Hot Box’.

This model falls under one of the more ornate home gardener types. While perfectly affordable it’s obviously not intended for mass production use, even so it’s design is very practical. (Jung Seed)

With all that said cold frames come in a slew of styles and materials but also these propagation units serve as a critical point in gardening use because they can be built from almost anything. Commercial models make use of aluminum fittings and polycarbonate panels to allow full entry of light whereas units marketed to home gardeners may be comprised of rot-resistant wood fittings and polycarbonate, Plexiglas or glass fittings depending on cost level. With that said the ones you buy are as varied as your willingness to spend.  With that said it is not expensive to build a cold frame yourself nor do you need those fancy parts and pieces to do so.

This type of cold frame comes in single (pictured) and double-sided models and is composed of polycarbonate panels and aluminum fittings. It is clearly intended for both home gardeners and semi-professionals. The price range is good and its size allows for numerous units to be placed in rows. (Park seed)

Of course it bears mentioning that when one is building their own cold frames one might not build them entirely above ground. In-Ground Cold frames typically are no more then 6-8” above ground level and may be upwards of two to three feet below ground. Such units may be walled with brick, or some sort of edging or more commonly cinder block. The advantage to this sort of cold frame is that the soil itself is a great insulator, you require a minimum of materials, weed encroachment is limited and barring major weather they rarely have water issues.

 This in-ground unit is constructed into a hill with an eastern facing to maximize light exposure for the plants inside. Notice the coverings up top are hinged and effectively permanent. The interior is lined also to prevent root encroachment.

Now when one is talking about building their own cold the options for how and with what are quite open. At the ranch we’ve constructed two working models thus far pending the installation of a third. Let’s start with the one I like to call the “Prairie Deluxe”. It’s called that because as the pictures show the walls are mainly made of wood planks and the main support are brick struts. Wood by the way unless actively burning has a poor thermal efficiency and therefore this unit is only good at short term storage of larger plants. Even with the lack of efficiency, the use of a blue tarp allows might to pass through and thus, the plants still get some light and transfer of air and moisture can occur albeit at a reduced rate.

As you can see it's very simply designed. We literally turned one of the low-tech growing benches into a cold frame by moving the wooden planks to the sides.

The original supports act as the only hard structure in the design, broken or irregular bricks hold the planks in place. The  brighter blue tarp in the background serves as the cover.

The second model is more in line with the principles of a basic cold frame. Nicknamed the “Brick****haus” (insert humorous expletive after brick). This tiny cold frame makes use of albedo, location and refraction to prevent cold damage to the plants inside. The bricks are faced so that the smooth side is facing in while the rough decorative side is facing out. This is because the decorative size is darker, and tends to trap more heat from solar exposure; the smooth sides tend to reflect it more. The inside thus never fully freezes. The glass on top is made of two panes of tempered glass for outdoor use. Both panes were salvaged from the wrecked door after the break in. Inside this unit right now are several Cilantro plants which can withstand freezing and cold weather anyway but benefit from the wind protection and protection from the recent temperature fluctuations. Ironically I guess you could say that some of that cilantro is likely to be the first herbs at the booth in the market in 2014.

Very simple by design, the brick cold frame is portable and very efficient by cost and material standards.

In short, cold frames are a useful tool to the home gardener as well as the producer, in a way they are the step before one considers the installation of a true greenhouse. Given the strange weather as of late; cold frames may become quite important to the sustainability movement because of their versatility and variety of styles to meet every gardener’s preference and budget. Of course the final decision rests with all of you out there what is it that you would like to see?  This brings to a close a belated episode of LITFM, Stay tuned for our next episode which discusses in brief the issues of GMO, Hybrids and Open Pollenated plants.

As always folks, Keep em Growin!