Suzanne D. wrote:
I live in southern Utah, zone 7 or 8.

I ran across this from So Cal that has a lot of data for planting
time versus harvest time:

http://tchester.org/analysis/tomatoes/index.html

Here is my current take on growing tomatoes, although they will not
set fruit if daytime temps are over 90F they also won't set fruit if
nightime temps are lower than about 55F.

I believe that some early setting varieties are early because they
set at lower minimum night time temp. (Got a ref somewhere for that, Billy).

So, what are your night time temps going to be in a couple months?
How late in the season do your tomatoes set?

I'm thinking that you will do better to buy some plants already started.

Jeff