Well, I have a makeshift setup with one of those heavy duty plastic shelves (4 or 5 shelves). I had some heavy black plastic that I have duct taped around the top and upper portion of the shelf. I have a cheapy little space heater at the bottom of the shelf, and a regular shop light wired up near the top of the shelf, and a two dollar thermometer sitting next to seed tray. I check my temp 2 or 3 times a day. Heat rises from the cheapy heater and warms the upper portion of the shelf nicely. My temps have been holding steady at right between 80 and 85 f. My seeds are planted in tray with either some very fine seed starting mix or some perfect starts (futuregarden.com). I used the seed starting mix last year and had nearly 100 percent germination.