Hi I'm Trisha an organic gardener. Cold frames and hotbeds are easy to build structures that can help you extend your season or give your plants a jumpstart cold frames and hotbeds are basically the same structure the only difference is that one is heated only by the sun and the hot beds have an alternative heat source. These are easy structures to build or there are kits available like this dual cold frame they consist of a sash made of glass old windows can work very well or plastic polycarbonate and a support frame made of wood brick or cement block. The front should be at least one foot tall and the back taller with about a one inch rise for every foot of frame cold frames and hotbeds should be positioned with a full southern or south eastern exposure face the front either southeast or directly south a wind break to the north or northwest is recommended a straw bale a building even an evergreen hedge row will make a great wind break a wind break should not shade your frame.
Mobile cold frames like this one are great for over wintering your half-hearty perennials or they can be positioned a few inches in the ground for better insulation and for more permanent structure. A hotbed requires a little bit more preparation you're gonna need some hardware cloth, some sand, a heating cable and some burlap. For an electrically heated hotbed dig down six inches if the soil is not well drained dig down twelve inches and add a layer of gravel lay some burlap down either directly over the ground or over the gravel add about a four inch layer of sand this heating cable with a thermostat will keep your hotbed warm all winter long so you can grow vegetables throughout the winter you can even start your root cuttings or you can start your spring vegetable garden. The thermostat activates at temperatures below seventy four degrees and it produces three and a half watts of heat per linear foot for warmer climates you may only need ten watts of heat per square foot if that's the case space the cable four inches apart in colder areas change your spacing to three inches apart. For fourteen watts per square foot it's important to lay your cable on an evenly graded bed and not allow the cable to cross itself once you've laid your cable down add another two to three inches of sand just lay your hardware cloth over the sand build or place your cold frame on top now add four to six inches of good soil on top and your hotbed is ready to go. If you have a cold frame and not a hotbed you can insulate with a burlap bag filled with leaves or are you can add heat with a light bulb.
Temperature control is crucial too much heat is just as bad as too much cold a temperature actuated vent opener like this is a wonderful accessory to automatically control temperature. Sashes should be raised opposite the prevailing wind to prevent your seedlings from being burned by the wind. Water your plants early in the morning so that in the evening when the sashes are closed the foliage is dry. Grow food all year long in a cold frame or hotbed and grow organic for life!