Scot, Do you have two lights so that you could turn on a light under the shelf also. The heat will rise and heat the soil. I have found that once I have the first tray under lights, I can drape a mylar solar blanket over the top of my shelves and it holds in the heat as well as reflects light back on the plants. I'm talking about one of those thin foil looking things that you buy in the camping department for about $3. I don't have a heat mat either, but I have never needed one. I also don't grow them in a room that is too warm, but I make sure they are warm during germination. I think they are healthier grown in a cooler room. Just MHO. Carol

I think you could safely leave them in the warmer room until they are all up.

They will be stockier plants grown at the cooler temperatures. If you put a thermometer under the lights at the height of the plants, you will find they are much warmer there than the rest of the room. Just be sure the room doesn't go a lot colder at night. My lights are stacked so the plants needing cooler growing temps are put down close to the floor which is tile over a concrete slab so it is cold as the outside (almost).

Scott,

Although the cooler temps in the sunroom might slow down the sprouting of the slow seeds, they'll still sprout. You'll get the quickest germination of tomato seeds at 75-95 degrees but they'll sprout at substantially cooler temps. I know from experience that volunteers sprout in my garden or around the edges of my compost piles in late March through late April when the soil is still pretty cool and the nighttime temps are downright cold.

Bottom heat speeds up germination but it certainly isn't necessary. I grew seedlings for probably 20 years or so before I bought a germination mat. I really only bought the mat could speed up germination and maintain a strict schedule of starting new seed flats every couple of days. After I seed a flat, it gets just a couple of days on the mat, and the seeds often are germinating well by the second day. Once the seeds are popping up, that flat comes off the mat and another one goes on it, and then I repeat that over and over and over again until all my seeds are up.

Before I had a germination mat, I used to place the freshly-planted flats on top of the refrigerator. On a pretty warm day, I'll carry a freshly-planted flat outside and set it on the concrete patio in full sun so it can soak up heat from the sunlight and the patio beneath it.

Once they're up, I keep all the seedlings except for the true heat lovers like peppers, at cool temps in the 50-70 degree range, usually on our screened-in back porch. Sometimes I'll let the seedlings stay outside all night once the nights are staying above 45 degrees. I carry a lot of flats in/out in late winter/early spring so the seedlings are growing at lower temps during the day, but still not exposed to below-freezing temps at night.

Seedlings grown in cooler conditions stay stockier and are easier to harden off than seedlings grown on at indoor temperatures for weeks and weeks. Of course, pepper plants are always the exception because they get cranky when they are cold.

Dawn

Soonergrandmom, That is a great idea about the mylar solar blanket.
I was worried about the room my seedlings were going to be in being a little to cool but it sounds like it will be okay.

Many years ago I purchased heat cables that are supposed to be put into the ground to make a hot-bed; but I stapled the cables (being careful not to get a staple into the cables) onto a board of the appropriate size. This was a lot cheaper than a heat mat and they have lasted for 8-10 years if you take care of them. I start my seeds on top of that in shallow trays covered with sheets of glass - I also pay attention to notes that advise whether seeds need light or darkness to germinate. As soon as they start coming up they come off the mats and under shop lights. My shop lights are on timers. I keep a fan on a timer to blow a light breeze over the plants several times a day - this makes a stockier plant. I have found that soaking pepper seeds for a day before planting will make them germinate much faster. I'm definitely not an expert but this works for me. I also agree that cooler temps after your seedling are up will result in stockier stronger plants - if I keep the room too warm they grow fast, tall, but spindly and weak.

As usual that is some great information.

I get a little frustrated with the germination time varying so much. I've moved all of the tomato plants to the grow lights even though I have only 50% that are up after 6 days. I actually probably have a perfect environment for germination and for seedling growth due to the furnace in the living room and my cool sunroom with the grow lights set up.

great thread! I feel a bit better now that my seeds are under a grow light, but in a room that is a bit cooler than the rest of the house.

In the past, I started on heating pads and waterbed heaters, as well as at room temps. Then they were moved either under lights (my pre-greenhouse days) or straight into the unheated greenhouse.

This year, my bottom heat options have all walked off and I can't find them anywhere so... Hubby's building me a box with a heat lamp in it, with screen on top on which the seed starting flats will go. I'll try to remember to take pics in a day or two.

(By the way, I save those little 3- and 6-cell trays from buying storebought plants to start my seeds in. Once they sprout, out pops the little trays and the rest of the flat can stay on heat.)

And, since I'm not feeling very comfy with this winter's temps, hubby's also in the midst of rigging me up a temporary light set up in the house. It's generally cool in here (we heat with wood, also) but the uninsulated greenhouse is sub-freezing on some nights -- far too cold for the seedlings. I'll keep them in the house, under the lights, this year until my Spidey senses tell me the greenhouse is safe for them.

I, too, like to keep the seedlings all on the cool side but I do baby the pepper seeds a bit more.

Diane

This is my first year growing under lights. What I do is sow seeds in 4" pots, then put them in a quart freezer bag. when they germinate, I remove the bag, and let them grow for a while. When I had a small greenhouse, I would bottom water, but now that I am growing in the house, I think top watering would be best. I am also trying to root cuttings from a mexican heather I brought back from Miami this week. I sowed all of Jay's tomato seeds that he sent today. and 5 varieties of flower seeds. I also winter sowed about 15 more varieties of flowers. All I have left is to sow 2 more varieties of tomatoes, eggplant, and pepper. James