I don't have a greenhouse
I'm real glad I have mine this time of year. I found it was nearly impossible to keep it cool enough in the summer. That's why my gals are in rolling tubs - outside all summer then back and forth at night in the fall, then inside all the time when days are cool.
I don't mean this like it sounds, but I actually have two "greenhouses". Here's my experiences with that.
The first is out of glass and aluminium, with those little flap windows that can be left elevated for air circulation, and a sliding door. I bought it at a garden supply store and had no hand in how it was designed, and I was not even thinking about stealth. It was a piece of work to assemble. The problem for any grow is keeping the interior at a plant-friendly temperature. Like
@greenjeans says, it can get really hot in there, so "hothouse" would be more accurate. In fact, after about mid-May, on sunny days it is way too hot in there for a grow. The real advantage of that greenhouse is in the off-seasons, like early Spring and then again after Summer's heat has faded in the Fall when it gets cold. It "lengthens" the growing season on both ends, but plants have to be moved out during the heat. It is also too small for the kind of plants I like to grow.
The second structure is the one currently in use, and built it myself. I designed it for stealth as well as for air circulation. Open on both ends, I set it up so the prevailing winds from the NE pass through from N to S. It faces E and gets good light from early morning till mid-afternoon in summer. On hot summer days, that NE breeze brings air movement and cooler temps inside, and the afternoon shade is more tolerable than the hot sun. (The plants are also on wheels, and can be rolled out if needed.) Then, when the weather gets cooler, tarps can be hung and later even a heater started up.
Overall it has been a real improvement for the grow, it enables me to offer the late-flowering sativas an environment they can tolerate. In fact, strains like the Malawi or Super Malawi Haze would hardly be possible for me to grow at this Northern latitude without it, because these tropical sativa strains finish in late November or early December. PHxM and Oldtimer's Haze would go into January, and maybe that is something for next year, depending on how this year's go.
Downside is obviously I am still learning about how to manage the heat that accumulates when it is closed up and the sun comes out, or the humidity spikes after a foliar spray (which can be lowered by taking off the front tarp and opening a back "window" to let the airflow through to remove the moist air). Like
@Grand Daddy Black says: Live and learn, in that order!
If It had a little humidity It'd be perfect !!!!
