I notice my Nettle Plant wasn't regrowing, even after fertilizing it, despite it working before. I had gotten one harvest out of it since fertilizing it.
I fertilized the Nettle, then saved and quit, re-launched the save, and the Nettle Plant had lost it's fertilization.
Fertilize replanted Nettle Plant, save, quit, and re-lauch. The Nettle Plant is no longer fertilized.