Happy Shatterday Jaga, a couple of things. If you have a dirt floor you need to cover it with plastic or a tarp to help with the moisture coming up from the ground. It's hard this time of year to not have mold. Also running a fan can help to dry the the plants so mold has a harder time growing. Sulfur will help by burning it in the greenhouse. Amazon sells them or you can make your own. Mine is a ceiling light can, fixture, with a green flood light bulb and a can above the bulb to put the sulfur in. Plug in and you are filling the greenhouse with sulfur smoke.I just had to take a few bits of mould from 3of the plants.
I am hoping that someone has a good way of dealing with mould, outside in a sweaty greenhouse made from plastic?