That's why I gave up on heating pads intended for relief from back pain, etc. I bit the bullet and bought a pad and thermostat intended for plant propagation.

I don't think it matters how constant the heat is if you're starting seeds for zone 5/6 perennials. More constant heat will probably get you faster germination, but the seeds will eventually sprout anyway and once they're up, the mat can go.

For plants like tomatoes, peppers and basil that really prefer warm soil to get started in, I think you will wind up with delayed germination or, in the worst case, rotted seeds if you plant them in soil that just isn't warm enough.

My seedling heat mat wasn't particularly expensive - maybe $12? It's just a plain black plastic one but it's on its fifth year in service. The heat holds better when it sits on a piece of cardboard.

This seller has regular seed starting heat mats for 19.00 and 4.90 shipping which is pretty cheap
http://cgi.ebay.com/SEED-GERMINATION-HEAT-MAT-For-10-x-20-Seedling-Trays_W0QQitemZ110228123426QQihZ001QQcategoryZ43555QQcmdZViewItemQQ_trksidZp1713.m153.l1262

I don't use heating mats. I have my seed trays in a room in the basement with a constant 70 degrees

No basements here. I got my heating mat and thermostat from Sunset Hydro off eBay. They pay shipping. Of course, they aren't giving it away: the price is slightly higher than other vendors, but for me the mat and thermostat were about four bucks cheaper when the dust settled.

My advice is to check craiglist, ebay or garage sales for older heating pads. We've got two old ones that have thermostats but don't turn off, they just maintain that temperature. I used them on my seeds, and I'm pretty sure that's not the reason they failed. hehe

Here is a link that might be useful: Sinfonian's gardening adventure

I use a old water bed heat mat. Cost 2.00 bucks at garage sale.

I use rope lights laid out under the seed trays. They give plenty of heat for germination of my tomatos, eggplant and peppers. They are the clear flexible plastic tubing with clear or colored lights spaced about an inch apart inside. they are used to accent home or room features like windows, roof lines, etc. A 12 footer can be laid out with three four foot looped runs in the shape of an "N". You can put two flats on them. Dollar or discount stores have then for less than 10 bucks.

Some cool alternatives here! I don't use heating pads either, but put seed trays on top of tall cabinets around the house. It's always warm enough up there since heat rises. I do this with as many as 10 trays at a time.

I picked up a heating mat to help with Stevia and pepper germination, this year. Perhaps I spent a bit much in my desire for immediate heat mat acquisition, but it seems to be doing the job. In 6 days on a heat mat, running 14-16 hours a day all my Stevia have germinated, and I have about a dozen bell pepper sprouts, out of 72. I plan to start a flat of tomatoes this weekend, as well as some more tender, slow growing herbs, then do more peppers next week sometime.

I've never grown from seed, so this is turning out to be quite the experiment.

I've always relied on either radiators or floor heating vents around the house. The heat isn't constant, but I figure it's not in nature, either. It seems to work. I'd be afraid to re-wire a heating pad, especially knowing it's going to be moist and unattended for long stretches of time, but that's just me.

How many hours do you guys leave the heat mats or rope lights on? Do you turn them off at night?

Thank you,

MH

mehearty - Leave the heat on constantly until germination takes place. Breaking the heat cycle slows or stalls the germination process.

Dave

Thank you Dave =)