The greenhouse with the set is a community lot that you can put down elsewhere. So the only difference between theirs and yours is that yours is on a private lot.
Also, even with the planters, your plants shouldn't be going dormant while indoors - only when outdoors (or planted during a dormant season, I guess). So I guess make sure you're enclosing all your walls and putting a roof on it.
I, too, have had it since release, and the station/sunflowers is a plus to me (while carrying the sunshine in your inventory, it's a nice moodlet for most sims). Also, you can drag them to nooboo inventories for an additional mood boost to them.