floralia
A 2002 eroge by Xuse involving gardening somehow. Obscure in the West, but apparently did well in Japan; it has an expansion, floralia plus, and several of the heroines got their own spinoffs.
Website: http://www.xuse.co.jp/product/008_ralia/
Spinoffs:
* shino-sensei no yuuwaku jugyou
* ui-chan no niizuma diary
* yunchu ~ojou-sama wa go-houshi chuu~