Jackie, the greenhouse is not a good thing for your semps. As Bev mentioned, it can get to warm and not enough air circulation. If you have an unheated garage, that would be a good place for them on rainy days. Once they get some damage from lack of good air circulation, to much direct sun, etc, the soggy soil only causes more stress to the plants.
Keep them dry for now. I would also place Uranus on a paper towel, not on the slick plate. The paper towel will help absorb the excess moisture. Or a paper plate.
Again, most of the time when new plants arrive, I plant them in shallow nursery trays and place on my covered deck out back. When they start to look a like they might be showing signs of drying out to much, I give them a small drink. After they get going I move them out to the beds.
Moving them to the beds works best in the spring or later fall when temperatures are more moderate and we have some rain.