I just got one this year. It is called Hydrofarm Seedling Heat Mat 20x20 Hydroponic. I can't give you much feedback as I just got this a couple of weeks ago but so far it works great. I also bought the grow lights as well and everything was shipped directly from the manufacturer. When I got the heat mat it was rolled up and I thought this thing is really stiff and wouldn't lie flat, but it did. I did buy this from a seller on Ebay (if you go there, read the feedback on sellers) and I did check many sites as well to read reviews but nothing really stood out as exceptional on the market. Took a chance and I gather from other folks they did as well. Julia

The cables are meant to be buried in the potting mix and not laid on top of shelves. I used a heating cable from Stokes several years ago. We built a heat table by making a framework of 2x4's, stapling hardware cloth to the bottom (to allow drainage), laying a sheet of landscape cloth in the bottom (to hold in the potting mix) then filling the "box" with several inches of ProMix, with the cable being buried in the mix. The whole thing was on folding legs that are available at HD etc. The table was setup in front of a large window and worked well for sticking cuttings for a couple months. Then suddenly the cable just quit working.....That was the end of that table. I went to using heat mats and found them much more versatile. I have now been using mats for about 5 years. I have one 4 foot one and 3 single tray size ones and they have been reliable and useful. You only want to put your seeds on heat for germination. Seedlings themselves prefer cooler temperatures and if left on heat will become elongated and weak. In fact, different seeds have different temperature requirements and some aren't put on heat for germination, such as columbines, delphiniums, coneflowers. You will need to look up the requirements for each kind of plant you intend to start.

Joyce I have a couple Hydrofarm mats and all heat unevenly. The only mat I have that has even heating is my 5' x 3' and that's made from a different material. Instead of the thin black plastic it's a thick heavy duty rubber. I bought it from a farm supply store years ago. I even out the heat on the smaller mats by placing a 1" thick piece of wood over the hot spot and setting the pot on that. That doesn't help when using the heat mats for a flat but it works well with pots. I've never tried a thermostat to see if that makes a difference but don't think that it would.

If you are starting under fluorescents, you really don't need a heat mat. I've done without for 50 years. Especially for a lot of greens - such as lettuce. Lettuce will start at temps just above freezing. You can easily start it in an unheated garage under lights nearly anywhere in the country. I keep the lights on a cycle that has them come on at night, and then they're off for the 6 warmest hours of the daytime. At 41F, it will take 15 days to germinate; at 50F, we're down to a week. At 59F, it takes 4 days to germinate. Good enough. Tomatoes don't really need bottom heat either. In fact, germination drops off as the soil temp rises to over 75F. You'll get 98% germination at 59F, in about 2 weeks. At 68F, you'll still get 98% germination, in about 8 days. By the time you hit a soil temp of 77F, germination is down to 97%, but it only takes 6 days to emergence. But by the time you hit 86F, germination is down to 83%. If you are starting inside in a heated space, tomatoes under fluorescents don't really benefit from bottom heat, and may be harmed - in combination with the heat from the lights, soil temps are likely to rise above the best temps. Peppers do best between 68F and 77F. Easily achievable, in a heated space, with lights alone. Even eggplants - for me at least - do fine under fluorescents without additional bottom heat. The tables I've seen give only a 60% germination rate, tops, at soil temp of 86F - but I swear I've never had germination nearly that bad. Maybe I've just never counted, or maybe the fact that I grow orientals almost exclusively makes a difference. I'll have to pay attention this year. But I've always started them with just the lights, no additional bottom heat, and they've always done fine. I'm guessing the sweet spot for eggplant is probably between 77F (reported 53% germination) and 86F where the 60% germination rate was reported. Also, I've no idea what type of eggplant they planted to get those measurements. I don't know, maybe some varieties really do have germination rates that low - but I'm pretty sure I've never planted such a variety. Spinach is right there in the same range (temperature wise) as lettuce. I imagine many leafy greens are in the same range. I really don't think a heating mat is all that useful. Better to spend the money on lights, a stand, plant trays, something to measure soil temp, and a fan, IMO. I've really not had a lot of use for a heating mat, myself. This post was edited by zensojourner on Wed, Dec 17, 14 at 18:13