Cold frames can become an essential piece of your gardening equipment by lengthening the growing season and by protecting your young plants from frostbite resulting from a surprise frost. The usual temperature difference inside a cold frame is 5-10 degrees higher than the outside temperature and this can drastically improve the conditions required for an early start on seeds and transplants. It also gives the gardener more time at the end of the season. In some climates, this seemingly minor difference in temperature can actually provide a year-long growing season by allowing you to grow through the winter.

Cold frames are composed of a back wall which is higher than the other three and a hinged top that is transparent to let in the sunlight required for growing and heating. They need to be set in sunny, southern facing locations which are well drained. Providing shelter from cooling winter winds is also a plus if it is possible. This protection can be provided by a structure such as your house, garage or shed or you can use a fence or thick hedge. Cold frames can be made of many different materials, including wood, plastic, concrete blocks and hay bales. The transparent lid can be Plexiglas, an old window or just a sheet of plastic. They can be built or bought. If the outside climate is still too cold to produce warm enough conditions in these little greenhouses, you can purchase heating cables to place in the soil at the bottom of the cold frame for that extra boost in temperature.

Some newer cold frames use passive solar energy storage in the form of black-painted barrels filled with water. During the day, the water in these barrels heats up. After the sun goes down, the heat is slowly released throughout the night to maintain the warmth in the frame.

Juwel cold frames can be found in various sizes and prices to accommodate most peoples' needs including a system which allows for the addition of an extension unit later on after you've fallen in love with the longer growing season cold frames provide. Parasene sells both single level and double level cold frames. The double level one allows for a larger amount of plants to be accommodated in a smaller footprint.

Either way, single or double, built or bought, cold frames are a wonderful addition to the garden!

To learn more about cold frames and cold frame related products, visit MasterGardening.com