you should be fine if you plant out in cloches or wow 8 week after seed start.

I am in zone 7 too and I started some seedlings on 2/4. May 15 seems pretty late to be the last frost date. There is a document out there called freezefrost.pdf if you google that name you will probably find it. It is the best source of frost data.

Your plants could be pretty big by the time you plant them out, but as long as you have the space that is a good thing. In my area I plant my tomatoes out on May 1st. That is not the last frost date for my area, it is when the soil is warm. If you run out of space inside and you need to plant them early they would need some sort of protective covering. There are a lot of innovative products on the market to help extend the growing season.

Also if you want to slow down the growth of your tomatoes don't transplant them into bigger containers as they grow. They won't look as healthy as they otherwise would but when it is time to plant them outside just bury most of the stem and they will bounce back and be fine.

Sounds like you are going to have some large plants to transplant to the garden.

I will be planting my tomato seeds this coming week to have them ready for the garden the first week of April. I've found that 6 weeks before they go into the garden is just about right. My peppers get about 8 weeks or 2 months as they are slower growing.

You don't say where in zone 7 you are but this worked for me in both Tennessee and Alabama, zone 7. My zone here in Alabama is listed as 7a but temperatures and number of consecutive frost free days over the last 10 years put my zone more like 8a.

i am in the middle of nowhere nevada. its a tiny town called caliente if you want to google it. and right now, by no means is it caliente. like i said, this is my first time planting toms out of texas, and i quite frankly, have no idea when to put them in the ground. i just decided that maybe some tom seedlings would cheer me up in hopes for summer. i think it is warmer here too than 7a, everyone says 10 years ago that it would get -15 for almost a week and the coldest it has been since i have been here is 1 or 2.

I was raised in central Texas in the Austin area. Daddy always started planting on St. Paddy's Day. I have lived 35 miles from the Oklahoma panhandle for nearly 40 years now. Our lost frost is usually around May 1st. Even in Texas, planting dates vary greatly. Visit a local nursery or a neighbor for the best information in your new location. Check out the online info also. Best of all experiment. Stagger your planting and make a record of what worked best.

Most of all, have fun with it or why bother.

Back up 6 weeks from set out date for small cell sets (4 or 6 packs).

8-9 weeks for large container (6"-8") pots.

For a may 15th set out date, seed march 1st.

Any earlier than that, you will be leggy.