Yes, the glass is too transparent. You might want to try a relection map on the panes to give it some zip. Another yes on the vents since most of the greenhouses I have seen have them to counteract overheating. A floor would also work well. One other thought, the door doesn't really look as though it's scaled correctly. You can probably correct that by making the pots smaller and the worktable shorter.

See your point about the table. The pots were just thrown in for show, in a rush too:) What kind of floor - wooden decking kind of thing?

Probably a stone or brick floor would be best. Wood might be damaged by the heat and humitity in a greenhouse. Marali

Uh-oh, just went and made a wooden one - see my new post above somewhere.