A gardener is someone who looks after plants.
Elim Garak claimed to be a gardener while working at the Cardassian embassy on Romulus. He also claimed that Edosian orchids were his specialty. (DS9: "Broken Link", "Inter Arma Enim Silent Leges")
In Q's anti-time future, Geordi LaForge claimed that Leah Brahms was "quite a gardener". (TNG: "All Good Things...")