Building a cold frame

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Radio interview source: Justin Hancock, senior garden editor, BHG.com

It's possible to eek a few more weeks out of your garden by building a cold frame. Cold frames rely on the sun for their source of heat, acting as a mini greenhouse.

Justin Hancock is the senior garden editor for BHG.com, and says a cold frame isn't complicated to make. Basically, it's four wooden walls to hold heat and a transparent roof to let in light. It doesn't even have to be a permanent structure.

"One nifty trick I've done in the past is to do hinges on each corner on opposite corners," Hancock says. "That way when you're not using the cold frame, like in the summer, you can fold it up flat and store it in your garage. And then just put the two sets of non-hinged corners together to create your box. And then on top, place your plexiglass or whatever."

Some people use old windows and doors over the top of their cold frames. Use something like a short 2x4 to hold the glass open a bit on warmer days, because you don't want to cook your vegetables. Propping it open allows heat to escape and air to circulate.