Prune purple flowering salvia in the spring after the last frost has passed in your area, and when new, tender shoots become visible.
Cut back any dead, broken, damaged or diseased stems down to the crown above the soil line. Carefully pulling all the cuttings from the plant keep it healthy and tidy, and makes room for new shoots.
Reduce the plant's size or spread by cutting back the branch tips or removing up to one-third of the longest, most outsized stems down to the crown. Spread the pruning cuts evenly through the salvia so you end up with a natural-looking and roughly symmetrical result.
Deadheading spent flower heads in the later spring encourages increased and repeat flowering.