I think your plan will work. Also anything to shade the sunny side works for me. Just Al foil has worked.

I think fiberglass should work.

Other ideas: Container within a container with Styrofoam popcorn layered in the bottom of the outer container and then stuffed along the sides in between the two containers. Drainage present in both containers.

Besides aluminum foil, painting the containers white can help as an alternative.

3-4" organic mulch on top to insulate the inner container. Standard rule is 6" clearance between plant and container wall for thermal mass/insulation; but insulative wall should mitigate that need.

I can attest that RootTrapper II containers work very well in rapid blueberry root development throughout the container. But gophers burrow right through the bottom. But if it were set within an outer hard container (and then insulated in between) that would not be a problem.

Provide western shade as well is easily accomplished with a 2 x 12 plank propped up on its side. I park mine also on and under the east side of a shade tree so they get overhead shade from about 11AM in the summer and transpiration cooling.

This post was edited by Fascist_Nation on Tue, Mar 18, 14 at 20:10