I had planter boxes of purple salvia on my deck a few years ago, and came out one morning to find each one beheaded, and the flower lying in the dirt next to where it once stood. I almost thought it was the lunatic kid next door, because it was creepy! But I found out it was birds -- I usually don't have trouble with birds (
), I feed them and I put pinwheels up, and that seems to ward them off. I didn't have a pinwheel on these because it was awkward, but I replanted the box and put one in and no problem. I don't have salvia this year, but I do have bee balm in containers with pinwheels and so far, so good! HTH!