I bought tomato plants too early to plant outside. How do I keep them healthy indoors?

I got a bit ahead of myself and purchased tomato plants to transplant into my garden. I did some research and found out it is not recommended to plant in our area before May 15th (today is April 21st) due to frost. How can I keep the plants healthy indoors? Will I need to put them in bigger pots or will they do ok in what I purchased them in?

I bought tomato plants too early to plant outside. How do I keep them healthy indoors?
~*~Keep them in the pots that you purchased them in. Place them in a sunny window and keep them watered. When it is time to put them outside make sure that you harden them off by getting them used to the sun and wind before placing them outside permanently.
Reply:Yes they will stay healthy indoors. Just place them in a sunny location, and water them by placing them in a pan of warm water. Never over water them because they will rot at the soil line. I live in northern Ohio area , and I grow my vegies from seeds each year. I don't plant any flowers or tomatos until all warnings of frost has past around May 28th.
Reply:They should be OK for a couple weeks. Water well and set them in the sun on warm days. You could use half strength miracle grow to water them, every other watering. If it is cold outside, put them by a window or under a fluorescent light. IF THE ROOTS START COMING OUT THE BOTTOM OF THE POT, TRANSPLANT TO A LARGER POT.
Reply:Just make sure you keep watering them. When you plant them you can plant them deeper to keep them from falling over. They will send out roots from the stem when you plant them deeper too.
Reply:Where do you live? I live in zone 6 - northeast Ohio...usually it's recommended not to put plants out this early, but it's been pretty warm in my neck of the woods, and only going down to the mid 50's at night. I potted a couple of geraniums today, and talked to a woman who worked in the Garden Dept. at Home Depot before I put them out. She says, that the way they protect their plants at those big stores when keeping them out overnight this early, is watch for frost warnings on the weather, and if it's supposed to frost they cover it with this very fine sort of blanket...are you a sewing gal? If so, it reminds me interfacing you use in sewing, it's just enough to protect the plant. I'm sure you could buy it there or at a nursery. I've also heard of gently covering them with newspaper 3 or more sheets thick...however you'll have to fiddle with the paper to keep it from crushing your plant, and blowing away! You could also put them out during the day and just bring them in at night. Usually by the first week of may, approaching very quickly now, you're pretty safe from frost. I think for two or three weeks they'll be ok in the planters they came in if you decide to hold off on planting...you're plant will tell you if it's unhappy, it will turn yellow or wilt/droop, or bust right out of it's container! :) Really, those "rules of thumb" are more or less guidelines, but nothing's set in stone. The biggest thing is just protecting the plant from frost, and it's really not that tough. Good luck!
Reply:The best place to keep your tomato plants indoors is in a window sill that gets plenty of sun. Make sure you water the plants once they dry out. They should be fine like this for several weeks. They will actually do much better like this, then they would if you put them outside. Tomatoes are heat loving plants, they do not like the cool weather, which typically stunts their growth. Make sure to harden them off, once you are ready to put them outside (once nights are ~60F). They will need some time to accumulate to the presumed temperature difference between your house and the outside. A very quick transition will shock the plant, and cause undesirable effects.