Interesting, and very different approach. :)

Since your shelves are tented (enclosed) you can accomplish a similar result by using an incandescent light fixture inside the tent. A 60 watt bulb puts out a fair amount of heat, a 100 watt bulb even more so in an enclosed area.

Still not a direct-to-the-soil heat source of course but can work.

Dave

I've been using my homemade rice heating pads placed underneath a baking sheet with the seeds on top of that, tented with a plastic cover, but this seems like a much better way to keep consistent heat for a longer period of time! Thanks!

I have two 2foot grow lights hanging above the seed starter.
Last night after I shut the lights off I noticed temps went down to low 60s.
Apparently the lamps give enough heat to raise temperature.
Went back up to mid 70s today after lights were back on.
I need to get a humidistat to check on humidity, I'm thinking it's good with the moisture on the inside walls. I realize everything needs to be opened up when sprouting occurs.
This is all experimentation,. which I enjoy doing.Sometimes I think more than actual gardening.....

Can anyone believe this ?
Not sure if I even do, or maybe it isnt unheard of and I am unaware.
The image here are of the seeds 48 hours after leaving the package

There are some great ideas in this thread! I usually just put my seed starting kit on top of the fridge. It's warm up there and they can't get bumped (I have children and a dog). This year, however, as we have moved into a new house, my cats love to sit on top of the fridge and nock everything down up there. Needless to say I am looking for a new setup this year.

Lights are a good source of heat. Here in Texas when we expect a freeze that could kill some tender plants we wrap a cage around that plant using what ever kind of structure that will surround and cover the plant most wrap this with plastic being sure it does not touch the plant. We place lights inside the structure for the heat source creating a small greenhouse. I am finding uses for those empty plastic milk cartons. By cutting the bottoms our and placing them over plants such as tomatoes as they stop producing as soon as it hits 95 which comes too soon in our area. I have also started to cut a hole in the bottoms of those plastic ice cream containers, leaving a flap which can be closed at night if the temps will drop too low for good growth. I am also thinking about maybe using other small white frosted containers for seed starting here in our area with a hole cut on the bottom for venting during warm days to prevent too much moisture build up. Again Thanks for the wonderful posts on gardenweb.
Paul