Expanding on Sarsmi's post, I also sell bonsai, vines, resources, etc. In addition to the plant and resource vendors, I also have a shop rune vendor I throw recalls on which, of course, sell steadily, and a garden deco vendor that sells vases, stoneware, corrupted trees and such.
Also, I have a "special" vendor who sells things seasonally. It's an opportunity to make a little extra gold without straying from being an exclusive plant shop. For example, I toss appropriate colored plants on her at Halloween, Christmas and so on. I sold a bunch of stuffies and roses in vases for Valentine's Day. Since there are no big holidays upcoming for awhile, I'll probably place extra rubble plants or tainted mushrooms on her. Good sellers and help keep the shop going.