The previous owners of my house (who were worse gardners than I am) had rhododendrons planted along the one side of my house. They look like they have been there forever because the trucks were thick (6 inches in diamter) and they were tall. Well, foolish me thought that they would die if I cut them down to the ground, but yesterday I noticed green sprouts coming out of the trunks. Digging up the roots is going to be next to impossible. Next year I would like to plant my tomato plants along that side of the house. What can I use to permanently kill the roots where they will rot away this Winter and next Spring? I'm not too concerned if it will kill the grass in that area, as right now it's just a nice little patch of weeds and rhododendrons that refuse to stop growing.