Yes, not only after it rains but even if it doesn't rain for the early spring time. Just according to how bad they are, it is actually most effective if sprayed right on the darned slugs and snails, but works pretty well as a deterrent also. During the early spring I have had to spray every few days, then taper off to every week, then every two weeks, then as needed. But, I have lots of mulch every where, and they have so many places to hide, most people would not have that problem.
