Usually I prune my berberis bushes right down to few inches off the ground after they flower in late spring and they push up lovely new strong shoots as a hedge....but I have a variety called Helmand Pillar which is grown as a solitary bush in a flower bed , this grows as a columnar bush and mine is about five feet tall ...... but it is now really quite scruffy....can I prune Helmand Pillar in the same way or will that spoil its appearance ? Thankyou Debs