I know azaleas are shallow rooted in general but would like some approximate depths of far they are likely to go. I want to plant some azalea kaempferi ‘johanna’ In a 2 ft high raised berm comprised of pine bark, compost, and some native soil. I do this to provide the excellent drainage they need. Will their roots eventually grow down the 2 feet? If so, is it bad that their roots touch yard soil when everything else above it is pine bark, compost mix? Will they go into shock because of the change in soil?