historically.. they painted windows white ...

more currently.. they tarp them with shade cloth.. of varying shade levels ...

as to your hiding them.. only you are going to be able to define what you can do.. in your GHouse .... at best we can only speculate ...

heck you could even rig up a large umbrella for shade .. the sky is the limit

ken

GLASS greenhouses were painted.

You might consider fashioning some boxes or panels using a light colored (not black) window screen. I would not try to prevent air circulation or you'll be asking for trouble. Increase humidity levels by keeping the inside walls and floors of the greenhouse sprayed wiith water.

If you find that you need to shade the whole greenhouse, shadecloth is your best bet. Even one with low density weave cuts down on light and heat dramatically.