Rosemary is an evergreen shrub with blue-hued flowers and narrow, aromatic leaves. A perennial in mild climates, rosemary typically grows in U.S. Department of Agriculture plant hardiness zones 6 to 10. Plant this Mediterranean herb as an annual in cold climates. Rosemary ranges from sprawling, prostrate cultivars to upright hedges. This woody shrub needs little care, but benefits from selective pruning throughout the year.
Pinch back rosemary tips at planting and at any time during the growing season to redirect new growth.Young rosemary plants grow from a single woody stem and long, slender branches. Pinch off the tips of the branches for bushier growth. Pinching encourages branching behind the pinch point. Young rosemary plants quickly put out lateral or side branches. Additional pinching on new growth encourages more side branches that grow into a compact shrub.
Its herbal qualities make rosemary a culinary favourite. Rosemary leaves flavour meats and casseroles. Add the herb to tomato sauces and cooked vegetables. Trim off sprigs of fresh rosemary any time of the year. Fresh rosemary planted outside a back door is easily accessible for the kitchen. Cut off a sprig with full green leaves just before cooking. Snip these leaves into sauces or strip off whole leaves for simmering dishes. Do not use the stem as it is often brittle. If you add the whole sprig, remove before serving as the woody stem may be a choking hazard. In spring, trim off a 6-inch branch and plant it directly in the ground for propagation.
Prune off damaged or dead branches immediately. Injured branches spread disease and attract insect pests. Like many herbal shrubs, rosemary develops weak and bare branches inside the plant. During the dormant season or early in spring, prune out dead or sparse inner branches. Cut them back to the main trunk or stem. This allows better air circulation and permits sunlight into the plant. Avoid pruning when rosemary is in bloom. Bees cover the fragrant blue flowers and sting unwary gardeners. Rosemary spreads by rooting where branches rest on the ground. Prune off ground-touching branches to minimise spreading. Remove bottom branches to discourage rodent nesting.
After blooming, shape by pruning off up to a third of the plant. For tall, slender spires, cut out older woody branches down to the base. For hedges or foundation plants, cut back overall branches to a mounded or square shape. Prune the shrubs at any time maintain their shape and space. Trailing rosemary is easily shaped to cascade over rocks or walls. In spring, prune away awkward branches and leave those that flow over the ground. For topiary rosemary, prune away errant branches at any time and pinch tips to retain the topiary design.