Q: My ‘Provençal’ lavender plants are a few years old and very leggy, which is not so good since they line a walkway. How can I get them back into shape? — Holly Dietor, Glen Arm, Md.
A: All lavenders should be pruned once a year to keep them low and full. Since you haven’t pruned for a year or so, renovation will require several steps. Start this spring, when the plants begin to regrow. First, brush the branches with your fingers to knock off any dead foliage. Then, shorten half the old, gray stems — roughly every other one — to within a few inches of the base. If you see green buds sprouting near the base of an unpruned stem, cut to a quarter-inch above a bud. This thinning will admit more light, awakening buds that are low on remaining old stems. When green buds form near the base of these stems, cut the old wood back to the lowest emerging bud. By early summer, you will have shortened all the old stems to a few inches above the base. In midsummer, use hedge clippers or hand pruners to shape the plant into a symmetrical mound, like a shallow bowl turned upside down. Next year, you will have bushy lavender, which will need to be pruned only once. In zone 7, where you live, and northward, you can perform that annual haircut in early spring or in midsummer, right after heavy flowering. In milder climates, pruning should follow summer bloom.