If you've not set clear expectations before now with BIL, I don't think there's much you can do. If you'd set it up in advance ( not two days before you leave) that in exchange for lesser rent, these are some things I will expect of you : mow grass (sounds like that's covered), weed these beds, these flowers over here grow best when deadheaded (wave arms above beds), these require daily watering (point), during the season this plant will grow very tall - stakes or trellis are needed...Tie with this string. In other words, it's just too late. In all honesty, if you've not trained him it's just not going to be done because he has neither the education nor the desire to do it properly. Unfortunately, that may be true of outside help as well. Without clear direction and expectations laid out, I don't think anyone will meet your standard. Perhaps the best you can hope for is a notch above "abandoned homestead" upon your return.