I have recently been buying up as many of these as I can, they actually do well as actual homesteads for your NPCs and Houseguests. I have been gradually transforming the outside area of Grand Psijic Villa into Arboria from Dragon Quest XI by placing these greenhouses around the large open areas and along the cliffs, then filling them with furniture like little see-through glass houses. I hope to post screenshots once its fully fleshed out, but I suggest picking these up as it can turn homes with huge open spaces look lively like your very own town / village.