Built a small greenhouse and have some questions
I'm new to gardening and am growing some vegetables in containers this year, living in central Oregon I know we have a very short growing season, so I was originally leaving all my plants inside at night, and bringing them outside during the day.
I've got 7 different 5-6 gallon pots with tomatoes, strawberries, bell peppers, and one pot with two hot pepper plants. So after awhile, I got tired of having to move them constantly, and also needed more room. My solution was to build a small greenhouse, my dad helped me with it the other day while he was visiting. Was pretty basic construction, we used wooden stakes from a garden store and 6 mil plastic sheets.
It came out pretty good I think, today it's only been around 80 degrees but I last read about 102 degrees inside the greenhouse. I do have some questions since I've never done this before.. how much does a greenhouse of this size need to be vented? It's pretty humid in there and I've had the door of it open all day, but am fairly sure it will need some other sort of ventilation. Should I cut a hole in the plastic on the opposite side of the door, to make a window?
Another question I have is whether laying the plastic sheet on the ground like I do is good, or if I should do something else. I didn't think it'd be a good idea to set them directly on the ground, but one thing I thought of is whether having that plastic would prevent the ground's heat getting into the greenhouse like I'd want it to at night. We have very cold nights where I live up until later in the summer.
Any recommendations you all have would be appreciated. I am trying to think of an idea to put a trellis inside so that when I transplant my kentucky wonder pole beans they will have something to grow on. Also of course my tomatoes will need something to grow on as well, should I get a tomato cage for each pot or use some kind of trellis for them as well?
Here's some pictures I took today of the set up.