Anna, the link that Tom posted has good info; but, as they point out, it is rather difficult. (I once had to move an asparagus bed that was totally overrun with quack grass and horsetail, and probably managed to kill 2/3 of the plants.) So, I would say give it a try, because if you don't try then you know for sure you won't have any of the plants. If spring isn't going to work (is your mom's house going to be sold?), I'd wait until late fall (or as long as you can), cut the stalks way down, and give it a try then. Also, if the plants have "berries" on them you might want to collect them once they turn red and start some plants from seed; I've had excellent luck at doing that to fill in some empty areas in my patch.
