What is gardening?

[shentino]

What exactly do gardeners do?

My guesses

* Plant trees/harvest trees
* Clean up "weeds" (which I assume are the splotches of flowers/bright green moss that pop up outdoors)
* Remove soft rubble? (sometimes I see rocky areas that look like rubble, I'd like to clean those up somehow, but they're not objects like the kind workmen dispose of after bulldozing a wall)

If I'm right about any of these, there are quite often patches of weeds and flowers that my gardeners refuse to clean up even if I hire a hundred of them...is that a bug?