Has anyone out there heard of 'Root Control Bags'? They are made of a non-woven felt-like material. You can grow trees and such in them. The roots grow right through and when axposed to the air, get air-pruned. I read about a peony-grower in the US that used them. Does anyone know where to get them in Canada? My local nurseries have never heard of the them BUT I KNOW THEY'RE OUT THERE SOMEWHERE!