I have started some tomatoes in a cold frame with supplemental florescent light and they have grown to about 5"in 3 weeks to give you some idea how fast they can grow.

no problem that can`t be worked out.Plants will be ready to plant out at 12in. as soon as plants buds for 1st true leasves,.pot up and put in 50 to 60 degrees. water from bottom with one fourth strength fish fertilizer. If they get to tall let them fall over it will not hurt them. Toms are tough and can take some hard treatment. In 3 weeks you should put them outside, In light wind-light sun 1to 2 hours a day, Increasing time outside each day. I use 12 oz dixie cups with 3-4 small holes in bottom of each cup to plant up, after cutting off one half 1/2 its tap root.

Starting in the next month or two is probably too early. When is your last frost date? I think I started mine some time in March last year and that may have been too early. I had them in the ground in late April which was taking a chance on frost. I think the plants might be hard to care for that high up but you can find a spot I'm sure. I had some lights under my stairs which is where my dog likes to sleep; I had to get down on my hands and knees to care for those. The dog was very upset.

LOL!

Well, here in Salt Lake County, UT, we have long winters & summers, and short springs and autumns. It's weird; things start warming up in late February, but there are a lot of false starts, and it's not uncommon for us to have a lone snow storm in late April, even if we hadn't had snow in weeks.

I don't know the spring frost date off hand. Judging by the sources on the web, it's probably somewhere between 4/18 and 4/26 (one site said 5/18, but I think that's way off).

If 'spring frost date' literally refers to the average date of the last frost, then late April seems plausible, as Winter often takes a dying gasp around then.

But generally, frosts are few and far between by then. If we have a frost in late April, it usually follows a week or two without frosts, so even though late April might typically be the spring frost date, I don't know if that's the best date to go by (maybe you guys can help me figure this out).

I mean, the average low creeps above freezing by March 11th, according to Weather.com. I know that this is only an average, and that in any typical year, I can expect several frosts after this date, but late April still seems a bit late to me.

But what do I know? Over the last few years, I bought my tomato plants at the garden center, and I always waited until May to plant them.

Use cool white bulbs. Plant bulbs don't deliver as much light and are usually over priced. There are pics of great setups and some good info on the subject in the forum below.

Here is a link that might be useful: Growing under Lights

Google intellicast.com or get to it somehow. Enter your nearest town, below city in tiny print click on historic averages. In monthly averages double click on April or May. You will see the daily averages for that month and the record lows. For Salt Lake City which I tried it looks like the first week in May is good. Tomatoes don't like cold weather so it is not just frost you have to consider. You might chance a few late April with walls of water on something like that.

From the date to plant outside you need to count backward the time to germinate and several weeks for the plant to grow. That way your plants will fit in your house.