Two years ago, I built a new porch between two very healthy holly bushes. I used sonotubes and portland cement to anchor the posts.This spring, both bushes have suddenly gone brown and seem gone.Any speculation on why?
It is possible that you damaged the roots of the hollies when you dug the holes. Also the very alkaline nature of the concrete leaching into the soil could also harm acid-loving hollies. Follow up all that stress with one of the coldest, windiest winters in recent memory and it was probably more than the hollies could take…especially if they face toward the west or north. Broadleaf evergreens like holly and rhododendron really too a beating over this last winter.