Yea they will sprout but some will pop sooner than others. If you want to heat it up you can put the dome on top of the fridge, the computer, turn a light bulb on near by etc. I've never used a heating mat to germinate and mine have done ok. I make sure to remove the seeds that have germinated from the humid environment and get them under a fluorescent shop light asap so they don't mold or become leggy.

Many people do with out any heat, just a warm place or room temperature, it just takes longer. I get a little concerned about placing a covered dome in sunshine though. Never heard it talked about, but I worry that under the dome it could get way too hot.
Kenny

Here is a link that might be useful: Click here

One thing I have done to give some extra warmth, is place a cooling rack over a heating register and place the seed tray over that. When the heat for the house kicks on, it warms the tray. Works like a charm and does not get them too hot.

Woow I placed on a HD dish receiver and its warm. I see condensation inside what do I do?

I have used my gas oven, the pilot light seems to keep the inside warm enough. Just make sure you put a sign on the door so you don't bake them! Check every day.

Kris2001: Woow I placed on a HD dish receiver and its warm. I see condensation inside what do I do?
Thats normal. Keeps them from drying out. Sounds like your good to go.
Kenny

I just started coleus in a flat over a loosely coiled rope light. They all sprouted in 4-5 days. I've heard they like it hot and humid. It really seemed to work for them as I got 100% germination, and I'm not usually that lucky w/seeds.

If you have a water heater (to heat your hot water) you could place your flat on that, but watch it carefully, once they sprout remove the top and take them off the water heater, place in either full sun or under grow lights.

Alberta

You say coleus is what you are planting. Your normal household temperature is warm enough, unless you live in an a Igloo. Bright light is important for Coleus, a surface seeder, to germinate. The purpose of the dome is to conserve moisture and most times added water will not required until after germination, when the dome will be removed to avoid damping off problems. Al

I am new to starting my own seeds, and I agonized for hours over supply catalogs and articles on the internet before deciding to bite the bullet and use the top of my freezer and refrigerator to germinate my seeds. Boy am I glad I didn't spend a pile of money buying mats.

I germinated about 96 seeds in damp paper towels in ziploc baggies on top of my stand-up freezer. Just be sure to check the germination process frequently - several seed packs said they would take @ 10 days to germinate, but when I checked at day 6, they were already sprouted and had their cotyledonary leaves. The roots tend to grow into the paper towel if you let them go too long - I just cut the paper towel apart and buried it with the root in order to avoid disturbing the roots. I had about a 95% germination rate, and the plants seem to be healthy and happy now that I have transplanted them to a growing mixture.

I did another 72 plants in a Jiffy peat pellet greenhouse the same way (on top of the freezer), and have had overwhelming success. The freezer is your friend.

I also did the rack over the heating register and my onion seeds sprouted in 3 days!

You can also put them on top of the frig!! It's warm up there-
just one of the reasons kitties like to be up there (-:

I have also covered a card table with oilcloth, and put a space heater underneath it on low, that was you could start several flats at one time.

I put mine on top of the dryer, because at the early stage I have found they don't need too much light to sprout. I leave the gro dome off the top to let the humidity and condensation dry out for an hour or so, so there is no mold either.

Hope this helps.

I use the dryer as well. I never thought about it, but I was at my mother's house planting Gloriosa seeds. I just stuck the pot in a window for a few days, but she put it in the laundry room for some reason. Everything I read said it would take several weeks for germination, but it took just over a week before I saw my first leaf coming up. She does a lot of laundry, so I'm using her dryer as my heating pad. Right now, I've got some seeds in a baggie, and I put a towel down to prevent it from getting too hot, but in peat pots, it wasn't necessary.