I keep mine in those cells until I transplant outside. It works well for me. Transplanting my whole garden into more pots is a bit much. If you wanted to though you can do it in about a week!

Here is a link that might be useful: Home Gardening

After first det of true leaves I pot up to 4" pots but thats coming from starter pots. Your using larger pots to begin so you can afford to wait longer. Pot up before they become root bound and all will be well.

If you don't need the heat source shut it off now. You'll get better plants with cooler nightime temps.

Thats true m ,

Pot them up to a container (16 oz plastic cups work great). You want enough room for the roots to get BIG. Dark colored cups to keep light away from the roots, put them in in a very cool enviornment 50*-55* with your flou lights as close as possible (it won't even hurt if they touch the bulbs).

After two weeks move em to a bright window with your lights on them until the seasonal light gets longer and time to harden off.

You should have a stocky stemmed, incrediblely fibourous root systemed plant that should thrive outside.

Heat mat is for germination only. Once sprouted the heat mat is no longer needed and can cook the young roots.

You can actually pot-up at any time - many of us do it at the cotyledon stage - but the norm is 2 sets of true leaves because they are easier to handle then. Your 2 1/2 inch cells may be good for a couple of sets of true leaves or you can transplant them now - either way. Time for a mild dilute feeding if there is nothing in the mix.

Dave

Thank you everybody for the replies___:>) I will get my tomato seedlings off the heat mat now, and just use the grow lights....thanks again...I love it here, you peeps are a forum of gardening knowledge___:>)