Am thinking of planting a smoke bush in an area that is enclosed by a retaining wall, but am concerned about the root system eventually growing big enough to displace the wall.
How can I estimate the eventual root system size to prevent or mitigate displacement of the wall?
Note: I am a shrub and tree novice. So if my question or the way I've asked it seems "off the mark" or if more info is needed, then of course that feedback is welcome. I did an online search and found articles that stated the "spread" as 10-18 feet, but could not determine if that referred to the spread of the branches, the roots, or both.
For example, if I know the eventual root size, then do I add some additional distance between the wall and smokebush, such as roots = 15 feet so planting distance is 15 feet + 5 feet?