Water bed heaters work well as under-mat heaters, and are designed to be somewhat moisture-resistant. A pan filled with sand can be placed over a mat to diffuse the heat to an area much larger than the original mat. I have put a heat mat under a metal oil drip pan, bought at an automobile parts store. I lined the pan with heavy-duty plastic (to prevent water corrosion of the pan) and filled it with sand. I set the plants on the sand.
For colder areas this can be enclosed in a topless and bottomless box built from a sheet of polystyrene house insulation. The foil side goes inside the help reflect light. A light can be suspended overhead. The top can be covered with clear landscape plastic to retain heat yet transmit light.
|
Threaded Mode
