Posted: 24/06/2014 at 11:38
It will do more than help if you extend the border. It will be the difference between success and failure
Plants to go up a wall shouldn't be planted right up against the wall, the soil will be dry and the roots of the tree next door will be competing as well, The tree will still be there and using water and nutrients, removing a few superficial roots will make no difference to the tree.
The roots of your plants will be restricted by a wall on one side, they need space all round.