If you were going to take an existing song and change the words to make it a plant song...?
All she wants to do is plants, plants, don't mind the heat comin' off the street.
Take me out to the plant store... buy me that genus and flats of wax (Begonias)
She'll be comin' round the garden when she comes
Won't you fly, fly, free bird (of-paradise)
Paradise by the greenhouse light. ...Ain't no doubt about it, we were doubly blessed 'cuz our plants were so darn green and they had no pests!