I peeked at those just sprouting seeds this morning and tiny little seed leaves were open. These are Salvia seedlings, so strictly speaking, they don't belong in this forumSo I have some seeds waiting to sprout/just starting to germinate on a seedling heating mat in lower 60's room (heating mat supplies +10º) but no lights, and some cool weather seedlings that sprouted already (from which I TOOK that heating mat after germination) but which are under lights. I'll be transferring the germinated seedlings under the lights out to the main Grow Light Area in the cold (we're talking upper 20's to 30's) no-window garage tomorrow after I set the area up with extra heat (40's to 50's) and new tubes of light, moving the just barely sprouted seedlings under the light, and setting out another tray of seeds on the heating mat.
But I did manage to get the basics set up in my main Grow Light Area (seed starting/growing area lit with lights) to move out the salad mix box (8 seeds each: lettuce, radish, beets, rainbow chard, miner's lettuce) Checked on them after one hour and, in the 28ºF garage, the GLA soil surface temp was 50ºF. So it's just about right. (I'll check before lights out to make sure they're not going to freeze.)After that, I was able to move the wee Salvias to the lighted indoor seedling area.
Tomorrow, I'll start the 2 kinds of cotton seeds and Broccoflower, Brussels Sprouts, Kale, 3x cabbage, and 4x Lettuce. Once these sprout, they'll also go out in the GLA.
The key to my transplant production shuffle is going to be moving the cold weather crops OUTSIDE just as the warm weathers germinate and need to go in the main GLA area (which will need to be modified to generate more heat, but by then, the garage temperature *should* remain up in the 30's and above. I want to set up some low tunnels, but, at the moment, the garden beds are all still covered in 20+ inches of snow!
I'm a bit worried myself. This is not my first year of gardening by any means, but it is the first I have started seedlings for just about everything. I normally went to the nursery's and bought all my plants. Just stay tuned to this site and everything will be okay.
You are in basically the same weather pattern as me give or take. I have been doing so much research that say's to plant later than I normally do. I have everything planned out for the 90% frost date not the 50%. So that has everything 
!
They have plenty of light, directly under the grow tubes 2" or so since day one, can't figure out what am I doing wrong...
But I need room in house, so in the ground the sooner the better.