Whether a holly bush can be pruned in the fall depends on the type of holly bush. Most holly bushes should be pruned when they're dormant in the winter.
Some holly bushes, like the American holly can be lightly pruned whenever they need it. However, if it is pruned in the summer, there will not be as many berries come fall and winter. Japanese holly bushes can also be lightly pruned anytime from midsummer to late winter. Yaupon holly should not be pruned at all, unless they need to be shaped. This type of holly must be pruned in the winter.