I'll give ya my take on it. I do not have much knowledge on starting seeds the way you are. I start mine in a greenhouse so it is a bit different.

I do use heatmats and domes to start my seeds. Mainly so they get an even temperature and humidity to get the seeds sprouted evenly.

Personally i keep my peppers on heated mats to keep the roots happy and lessen any chance of stunting them or stressing them.If it is really warm out in the greenhouse i will remove the heat mat during the day time and replace it for the night.

Doing different plants can be a challange when some like it warm and some like it cool.trying to keep them temps at a happy medium is not always easy.

I'd get the broccoli off the heat once they sprout. they should only take a few days to sprout on a warm moist enviroment.peppers will take a few days longer most of the time.

And remove the domes if you use them as soon as you see the seeds germinating. other wise the seedlings may mold on you and get leggy trying to gather light through the dome.

I dont know if any of this is helpful to you or not. I know there are several folks on here that do start seeds like you are doing. Hopefully they will add some more advice for you.

Mia,

If I was starting seeds in a greenhouse like Busy1 does, I'd leave peppers on the heat mats after they sprout because they don't like cold temperatures. Also, being exposed to cold temperatures can cause the pepper plants to stunt or stall or to remain unproductive long after the cold temperatures have abated.

Since I start my seeds indoors at the present time (my geenhouse is under construction, though, so next year will be a different story), I take the flat off the heat mat as soon as the seeds have sprouted because the indoor air temperatures are warm enough for them. My seed-starting shelf is indoors in a room that that stays moderately warm, although cooler than the rest of the house at times because we have closed off the HVAC vent during seed-starting so the room stays cool. I like to keep that room around 60-65 degrees, although it may get a bit cooler on cold nights.

So, feel free to rotate your peppers off the mat as soon as they sprout and use the mat to start something else.

I only use the mat for peppers. Everything else sprouts just fine without it, but that's indoors. Your garage may be cooler than my seed-starting room and you may need the mat or some other heat source at night.

Having said all that, a heat mat is not required, not even for pepper and eggplant seedlings which tend to be sort of finicky. I started pepper and eggplant seeds indoors for years and years without a heat mat. The seeds just sprout more slowly without a heat mat, but you often can place the flat on top of a refrigerator, a clothes dryer (while it is running) or some other heat source and get good results too.

I'm linking Tom Clothier's Seed Germination database below. Look at each individual type of vegetable and you'll see which ones sprout more quickly at warmer temperatures, and which ones don't really need a heat mat. The info might come in handy when you're making decisions about whether to grow on a mat or not, or whether to direct-sow. It also tells you how quickly you can expect direct-sown seeds to sprout in various soil temperatures. You can check you soil's temperatures with a plain old kitchen thermometer. (I keep my kitchen thermometer in the shed so no one carries it inside and uses it with food by mistake.)

If you have more questions, just ask and everyone will be glad to answer. We have many, many experienced seed-starters here.

Good luck,

Dawn

Here is a link that might be useful: Seed Germination/Temperature Database

....and not so experienced seed-starters who can lurk and glean all manner of information!

bwahahaha!!
dody :)

Thanks so much for all the info, busy1 and Dawn. To have my own greenhouse *sigh* if only! I went home at lunchtime to remove the domes (having left them on thinking "ooh, it's like a tropical vacation for these seedlings"). I'm guessing the domes should come off even if every cell hasn't sprouted? Next year I will know better than to mix different temps, different plants, etc. in one tray.

I did try the flats on top of the fridge first, but maybe because ours has a freezer on top, the top of the fridge was very cold! I ended up putting them on the counter over the dishwasher until the first sprouts came out, then about a day or two later (when they starting leaning toward the kitchen window) moved them out to the garage and the florescents.

That chart is very useful. I'd looked at it before from searching the FAQs but didn't really understand what I was looking at until you all helped explain it to me. Sometimes you gotta wait for it to click, I guess. Now I'm going to stop and pick up a thermometer on the way home. I'd thought I would just use the old mercury one in the medicine cabinet, but found it only started reading at 94 degrees so will find something else.

Thanks for all the help, everyone!

Mia,

I've been wanting a greenhouse forever and was starting to think we'd never get around to building one. I received the geenhouse kit as a Christmas present from my DH, but since he's either at work, or commuting to/from work (he drives about 85 miles one-way) or out fighting fires (he's the chief of our volunteer fire dept.), I wasn't sure we'd even start building it this year. We tend to take forever to finish any project we start.

Now that I'm about to have my own little greenhouse, I want Busy1's greenhouse because it is so much bigger than mine! Busy1 has been very gracious and helpful in offering me advice on aspects of greenhouse-building and operating.

The issue with the dome over the seedlings is a complicated one. Because I grow indoors in a room that has a southward-facing window and a westward-facing window, I remove the dome as soon as the seeds sprout because that specific room stays warm and humid and the plants can stay too humid and develop damping off if I leave the dome on. Busy1's seed-starting is in a greenhouse so the conditions are different, hence the need to keep the dome on. With seed-starting, it is sort of a learn-as-you-go process because the conditions will vary depending on whether your seed-starting flat is in a warm room indoors, a cool room or basement indoors, a garage, a shed, a sunporch or a greenhouse. With time, you'll figure out what works for you in your specific conditions just as the rest of us have figured out what works for us in our conditions.

Next year, I expect to pick Busy1's brain a lot to learn what I'll have to do differently when starting seeds outside in a fairly cool greenhouse. I'll likely keep the greenhouse somewhat warm with a greenhouse heater, but it won't be nearly as warm as the house, so I'll have to modify my procedures accordingly.

Because of efforts to make refrigerators more energy-efficient, I don't think most modern-day refrigerators get as warm on the top as they used to. I can remember 20 or 30 years ago that seeds sprouted quickly on top of refrigerators, but I think refrigerator tops aren't as warm now as they were then.

It does take some experience with growing from seed, both in the ground and in flats, for the germination and temperature chart to make a lot of sense. For example, once you're waited 20 or 30 days for carrots to sprout in cold soil, the numbers on the page really mean something to you. One year, in an effort to get carrot seeds to sprout (my whole garden slopes, so I have trouble getting carrot seeds to sprout before rain washes them downhill into the woods), I started them inside, using cardboard rolls (from toilet tissue, paper towels and wrapping paper). The seeds sprouted in 5 or 6 days (this was years before I found the germination chart) and it was too cold to transplant them out, but I planted them out into really cool soil and air temps and they did fine, even though they were in the ground about 3 or 4 weeks early. I got lucky that year because it wasn't a terribly cold February. So, I got to see first-hand the difference between how long carrot seeds take in cold soil vs. warm soil.

It is the same thing with peppers. I grew peppers indoors for eons before I bought a heat mat. They germinated fine, though slowly. Then, with the heat mat, they popped right up in just a few days. What an amazing difference! I love my heat mat because I do grow a lot of peppers, but I only use it for a week or two out of the year.

Many years ago, I'd see both soil thermometers and compost thermometers in one of my favorite organic gardening stores in Fort Worth, and I'd roll my eyes and say to myself "why in the world would anyone take their soil's or copost's temperature?" Now I find myself being the one taking my soil's temperature, although I certainly didn't drive to a gardening supply store and buy a fancy soil thermometer that is virtually identical to a simple meat thermometer that you can buy in the kitchen supply section at any store. I refuse to take the temperature of my compost, and to do that, you really would need a compost thermometer with a long probe like the ones sold by garden supply companies.

Dawn

Thanks again everyone for the info. I've been reading the other recent posts on seed starting and greenhouses and cannot believe how nice you all are to go out of your way to help others along their gardening journey!

I got my heat mat on Monday night, hooked it up, and by the next morning all the tomato plants had sprouted (they were planted the week before at room temp). Anxiously awaiting some activity on the peppers! With cold temps in the garage I've only gotten the soil temp up to 72 (from 50!) but it's still much improved.

Gratefully,
Mia