DaveP wrote:

There's no problem with any of the tree heathers you mention. They
all form root mats that do not penetrate down very far and most
importantly, are incapable of pushing through relatively thin plastic
barriers. The same is true of the Azalea section of Rhododendron
(both evergreen and deciduous forms) and most dwarf Rhododendrons.
Andromedas and Pieris are also similarly rooted and work well with
heathers.

Thanks very much, Dave, for the assuracne re. the tree-heathers. And
thanks very much too for mentioning Andromedas and Pieris.

I knew about rhodis and azaleas and have a couple of them in already.

Cheers,
Eddy.