Thank you, everyone, for your ideas and experiences! I'm now thinking that the water bottles are not helping. Too small, not enough actual sun hitting them, etc. So out they go.... well, experiments are best if they cost nothing and don't make anything die....
You were right.
Everything in the greenhouse is looking extemely happy. I'll take a picture and post it later. I made a "greenhouse cozy". (You know, like a teapot cozy only bigger and without the calico print
) It's 60% shadecloth, sewn to fit over the greenhouse with minimal tie down. Can be swapped for heavier shadecloth this summer if needed. But right now it's ideal.
Thank you again,
Joanie