The herb Rosemary, Rosmarinus officinalis, is winter hearty in zones 7-10. Franklin County is in zone 6 so is not reliably hearty here. Perennial woody plants such as Rosemary should not be pruned in the fall. Usually no pruning of these plants is done within 6-8 weeks of a severe freeze. Pruning in the fall can stimulate new growth with that growth not having time to harden off and thus being killed by frost. Mulching the plants with 2-3 inches of organic matter after the first hard freeze will protect the roots. After the plants have been uncovered in late winter necessary pruning can be accomplished.

Sources: Michigan State University, North Carolina State University, and University of Illinois.