I am in zone 7a also... I water/increase humidity with a mister system 24" from the ground... attached to the walls of the greenhouse... FYI... I do grow in ground... not pots...
I’m in zone 8. 8x16 greenhouse. Mostly Tropicals, heavy on the orchids and Nepenthes, but some food things, too. I water with a shower head waterer. I make sure to soak the gravel and the boardwalk. I just watered and am sitting in here feeling tropical!