Flowering outdoor plants

How tall do they usually grow until they flower?

There is a variety of factors that go into the question and the answer. In other words, it all depends.

Hmmm, well I live in Arizona, and my plants usually get light from 10am-5pm. And for the strain, just reg.

Did you just start them? The strain is also a factor, so if you don't know then that can make it more difficult. Also, if you just started them but aren't near the equator (I don't think Arizona is quite close enough), then I couldn't say with any certainty how much they would grow before trying to flower. Indoors you would have more control of these variables.