If they are native plants they would get by with mostly just water. Also would not be too costly to hire somebody to do the occasional trimming and fertilization.

I'm a gardener who obsesses with automation and irrigation, what I would do here is select plants that have a size limit (you can get vines and whatnot that top off at x feet), run some kind of irrigation down the building to distribute rainwater, and you can inject fertilizer into the line.