Here is a link to the step-be-step FAQ here on how to grow tomatoes from seed. Be sure to check out all the other FAQs here too - just click on the FAQ button on the top of the forum page - as there is one on the lights needed, temperatures, transplanting once germinated (be sure to remove the cover as soon as they sprout), etc.

Dave

Here is a link that might be useful: FAQ - How to Grow Tomatoes from Seed

optimal temp for tomatoes is 70-75 degrees, with 65-85 being the good range (from jeavons "how to grow more veg")

I wouldn't want to put young plants at 50 degrees, although at the end of the season, old timers can take it, and the soil is probably still warmer than that.

In zone 4, you'll be waiting a long time to put them out. Here in zone 5 april is a no no for tomatoes without protections.

If you can provide a little heat to them in the garage till whatever your plant out date is, that might work if they have enough light. I'd try to keep them at a minimum of 60, but I'd aim for about 65-68, unless you want them to grow a little more, then 70 would likely have them growing at the expected rate, a bit cooler would slow them down.

I made room in the basement so I can have 6-9 flats under lights should be able to keep it at 60 in that room and put a fan on them 2 times a day. then in mid april I can put them under a coldframe or the greenhouse.