Dead roses and soil
I pulled all my knockout rose bushes due to a fungus. Do I need to treat the soil before planting something in that flower bed? The bed is now empty except for mulch.
I would take a couple samples of the soils in and have them tested. Let them know why you are having the soils tested so they know they are looking for something that killed the rosebushes. Knockouts are not easy to kill by any means! If it was the nasty Rose Rosette Virus that caused the problem, Having the soils tested is always a good idea so that you know what you may be dealing with if it is not the rose rosette virus.