Rhody Root System
Can someone tell me if a rhody's root system grows horizontally and shallow or vertically and deep? I have an electrical sub-panel in my yard that I want to screen with some rhodies. I have built a small stone wall around the sub-panel and created planter "boxes" out of stone as part of the wall. The bottom of these boxes are just bare ground - meaning they are not completely enclosed boxes. I am thinking about filling the boxes with dirt/compost and planting rhodies in them, but I am wondering if they will try to grow horizontally through the boxes or if they will grow vertically down to the bottom of the boxes and into the ground underneath the boxes.