Growing Rosemary
Rosemary (Salvia rosmarinus, formerly Rosmarinus officinalis) is a woody, evergreen perennial herb native to the Mediterranean region. It is one of the most rewarding herbs to grow because an established plant will produce abundantly for years, requires very little water or attention, and maintains its flavor year-round. Its needle-like leaves carry a strong, piney, slightly camphor-like aroma that pairs beautifully with roasted meats, potatoes, bread, and olive oil.
Planting
Rosemary can be started from seed, but germination is slow and erratic (often 2–4 weeks with only 50% success). Most gardeners start with nursery transplants or root cuttings from an existing plant. To take a cutting, snip a 4–6 inch stem tip, strip the lower leaves, and place in moist sand or perlite. Roots should develop in 3–4 weeks.
Plant in full sun with well-drained soil. Rosemary absolutely will not tolerate wet feet — root rot from poor drainage is the number one killer. In heavy or clay soils, plant in raised beds or containers where you can control drainage.
Care
Once established, rosemary needs very little water. In most climates, rainfall is sufficient except during extended dry spells. Overwatering is a far more common problem than underwatering. Do not fertilize heavily — lean soil actually produces more aromatic plants. A light application of compost in spring is more than enough.
Rosemary is hardy in USDA zones 7–10. In colder regions, grow it in a container and bring it indoors before the first frost. See Overwintering Herbs for tips on keeping rosemary alive through the winter indoors. Indoors, it needs the brightest window you have and good air circulation — it is prone to powdery mildew in stuffy, humid rooms.
Pruning
Prune rosemary regularly to maintain shape and prevent it from becoming woody and bare at the base. The best time to prune is after flowering in spring. Never cut into the old, woody growth where there are no visible green leaves — rosemary does not regenerate well from old wood. Instead, trim the green, flexible growth by up to one-third.
Harvesting and Using
Harvest sprigs as needed year-round. Strip the leaves from the woody stem by running your fingers down the sprig against the direction of growth. Fresh rosemary is potent — use about half the amount you would use of dried. It holds its flavor well during long cooking, making it ideal for roasts, stews, focaccia, and compound herb butters. Rosemary also dries exceptionally well; see Fresh vs. Dried Herbs.