You can make the greenhouse roof as little as one tile wide, so it makes an excellent replacement for awnings over hot tubs. Like so:
Unprotected hot tubs can be a tad dangerous in Seasons if your sims use them during a storm. I hate the way the awnings stay visible and get in the way.
Ack, there's no "toast" or "lightning bolt" smiley.
Btw, a plantsim (yuck) would probably be fairly happy in that house. But not a plantsim-vampire (double yuck) they need a purely technological solution.
MikeD