Nervous? You and me both. I'd be very careful with rare tomato seedlings. Any thing even close to freezing and I'd put them in the shed for the night. I'd bring them out as soon as the sun came up, though. The exposure to low temps and rapidly fluctuating temps is what makes them hardy. Just my two cents worth.

Martha

I haven't started some of my tomatoes for this very reason. I guess I have been around this forum long enough to know that I should just do it...if I dont succeed, I can always start again. Just afraid of failure.

Like Martha, I give my tomatoes and all tenders protection if there's a frost. I'd take the covers off now if they've germinated- too much risk of frying them if it's warm. Just protect them overnight if a frost is possible, uncover after frosty conditions are gone.

Karen

Thanks for the responses! We're heading toward cooler weather, rainy and down into the 40's at night, so I'm going to leave the tops on a little longer in case we get even colder. (They're in clear, 1-gallon juice jugs, with the lids off.)
I think I'm so nervous because, while they were Winter-sown, they didn't really get a chance to freeze; I worry that they're not as hardy as they otherwise would have been. On the plus side, I'm over a month ahead of where they would have been, which bodes well for the longer-season types I'm trying. It balances, I guess. :)

We're going back to 20's at night, after a couple of weeks of 70's-80's day/40's-50's night. I'm freaking out too. I've got lupine, bachelor buttons, rose campion and delphinium sprouts in my milk jugs. I cut off all the tops for our heat wave and will spend some time tomorrow putting them back on.
No shed here, but there's an unheated attached garage.

I put the happy tomato plants in new peet pots with two leaves. They are strong and getting bigger. Anyway since I am a fluffy type gardener I put the peet pots in baskets - about 6 - 8 of them. They look very pretty. I put a nice bunch of paint plastic over them and hooked them securely. Hear there is a below freezing day coming up and I think the clear plastic should bring them up by 10 degrees. I'll take this off when it gets warmer and recycle it. It cost a whopping $1.39 at Sears Hardware, where I get hummus/manure for 2 bucks a bag with a 30 cent rebate. Guess who stockedup on that crap.
J

Seedlings are going like gangbusters! I brought the containers in one night, when temps dipped into the 20's, but otherwise they've held up extremely well. I was forced to transplant the Giant Beefsteaks (these are being grown for a friend of mine), they were so crowded in their container, and since their cups are uncovered I'll probably be moving them inside on colder nights.
I'm in awe of how well the Extreme North and Fantome Du Laos are doing! Plus, I just now have a Purple Dog Creek seedling; I only had 3 of these seeds, and they were sown over a month ago, so I had about given up on them. *happy dance*