A brief history of cold frames

Saturday, February 20, 2010

Where did cold frames come from? Old green house

Cold frames were originally designed as an adjunct to a heated greenhouse. The concept was that once the seedlings had been grown in the heated greenhouse, they could be hardened off in the adjoined unheated cold frame.

Traditional cold frame designs were planned when the greenhouse was build and the frame would have been incorporated into the brick foundations, frequently running along the whole length of one side. The cold frame was usually situated on the southern side of the greenhouse and may even have included a small door or hatch allowing access to the cold frame from within the greenhouse. All cold frames feature the ability to open the roof light (the glass lid of the cold frame), giving the ability to control the temperature relative to the outside environment.

Modern cold frames

Modern cold frames share the same features as their predecessors, the sloping glass roof, south facing position and the ability to open the roof light by varying degrees. These days, it is common to see cold frames used in isolation, both for the propagation and hardening off of young plants, frequently where there wouldn’t be enough space for a greenhouse. With the costs of heating greenhouses rising, many users are using soil warming cables and other methods to create so called “hot frames”. Ironically these hot frames are frequently used as an addition to an unheated greenhouse!

With renewed interest in vegetable gardening in recent years, cold frames have seen a comparable upsurge in usage, particularly as they are compact, inexpensive and easy to install. The ease of hardening off seedlings when using a cold frame coupled with the ability to grow crops earlier in the season makes a cold frame an excellent investment for any keen gardener.