I think pruning your hedges that far back in the fall is a bit risky. I have seen laurel hedges recover from stumps in the ground but it took three years before they looked green again. A better solution would be to wait until new growth in spring is seen - April or May and then prune so the summer growth would quickly cover the woody stumps. This would also be a thoughtful way to protect the birds from winter storms. If you must prune in the fall limit the amputation to one third of the top and side growth. Laurel hedges will freeze and die almost to the ground if there is a hard winter but they always seem to sprout up again in late spring - and look naked for years as they recover. This high maintenance monster is not my personal favorite but I do have several that have volunteered in my own yard and the big green leaves do add some winter structure. Keep growing, Marianne Binetti