I have several blueberry bushes growing in pots of acid soil. I am considering growing them as follows - dig a suitably sized trench; line with either fabric weed control material (which is porous) or plastic sheeting pierced to allow drainage; and filled with ericaceous soil. I am not sure if the porous fabric would lead to a 'leeching-out' of the acidic qualities of the new soil. Has anyone any experience of this method? Any comments or advice would be much appreciated.