|My brother has seen plans in gardening magazines that involve a heat cable buried beneath the soil in a cold frame. Do you know of any suppliers that have this sort of heat cable or heat mat that can be buried underground?
|In my experience, plain linear heating cables are always set under a layer of sand or soil according to the manufacturer's directions while mats can be used on a bench. Charley's Greenhouses http://www.charleysgreenhouse.... offers cables and mats and has on-line plans for a propagating bed as well. Do be careful to always follow the manufacturer's instructions for safe use.