How to Grow Rosemary

Rosemary (Salvia rosmarinus, formerly Rosmarinus officinalis) is a fragrant, evergreen Mediterranean shrub grown for its needle-like aromatic leaves, used extensively in Mediterranean cuisine with roasted meats, potatoes, and bread. In frost-free climates, rosemary grows into a substantial shrub several feet tall that may live for decades. In colder climates, it's grown as an annual or container plant brought indoors for winter.

Rosemary is one of the most drought-tolerant and low-maintenance herbs available to home gardeners. Once established, it thrives on neglect — requiring minimal water, no fertilization, and just annual shaping. The challenge is providing it with what it fundamentally needs: sharp drainage, full sun, and protection from temperatures below 10°F. Poor drainage in clay soil or overwatering kills rosemary faster than cold.

Growing Tips

Never overwater rosemary. The number one cause of rosemary death — both indoors and outdoors — is root rot from excess moisture or poor drainage. In heavy clay soil, amend heavily with coarse sand or perlite, or grow in raised beds. In containers, use cactus/succulent mix rather than standard potting soil.
Prune rosemary lightly after flowering in spring or after the main flush of new growth. Never cut back into old, brown wood — rosemary doesn't regenerate from woody stems without leaves the way many other shrubs do. Always leave green growth on any stem you're pruning.
Take stem cuttings in late summer to propagate plants for indoor overwintering or to share. Take 4–6 inch cuttings from non-flowering tips, remove lower leaves, dip in rooting hormone powder, and insert into moist perlite or coarse sand. Keep moist but not wet. Roots form in 3–6 weeks.
Indoor rosemary is prone to powdery mildew and spider mites in the low humidity of heated winter homes. Improve air circulation, keep the plant in the sunniest window available, and mist occasionally (though wet leaves can promote mildew — balance is key). A humidifier in the room helps.
Harvest rosemary by cutting fresh stem tips 4–6 inches long. Regular harvesting maintains the plant's bushy shape. Fresh rosemary keeps for 2–3 weeks wrapped in a damp paper towel in the refrigerator. Dried rosemary retains excellent flavor for 1–2 years — dry by hanging bundles in a warm, ventilated location for 1–2 weeks.

Companion Planting

Rosemary's aromatic oils are cited as deterrents to certain pest insects, with limited but supportive research for reduced cabbage moth oviposition nearby. As a drought-tolerant perennial, rosemary is an ideal companion for other Mediterranean herbs (thyme, sage, oregano) in well-drained beds. The planner helps you place rosemary and other perennial herbs in dedicated permanent zones.

FAQ

When should I plant rosemary?

Plant rosemary transplants in spring after your last frost date, or in fall in warm climates (Zones 7+). Rosemary is a perennial in Zones 7–10 and can be planted anytime in those zones. In colder zones (5–6), plant in spring and protect through winter or grow in containers brought indoors. In Zones 3–4, treat as a container annual, overwintering indoors on a sunny window.

Why is my rosemary dying?

The most common causes, in order of frequency: 1) Root rot from overwatering or poor drainage — rosemary needs sharp drainage and infrequent watering. 2) Winter cold damage — temperatures below 10°F kill most varieties outdoors. 3) Indoor low-light and low-humidity conditions causing decline. 4) Powdery mildew from poor air circulation. Check the roots — if they're brown and mushy, root rot is the issue; if white and firm, look for other causes.

Does rosemary come back every year?

In Zones 7–10, yes — rosemary is an evergreen perennial that grows year-round. In Zones 5–6, it's a tender perennial that survives mild winters in protected sites but may die in harsh winters. In Zones 3–4, rosemary does not survive outdoor winters and must be brought indoors or treated as an annual. Choose cold-hardy varieties like 'Arp' or 'Madeleine Hill' for the best chance of survival in marginal zones.

Can I grow rosemary indoors?

Yes, though it requires substantial light — a south-facing window with 6+ hours of direct sun is the minimum. Supplement with grow lights if sunlight is insufficient. Water sparingly, allow soil to dry between waterings, ensure the container drains well, and provide some air circulation. The main challenges are insufficient light and overwatering, both of which lead to gradual decline.

How do I use rosemary in cooking?

Rosemary's strong, resinous flavor works best with robust preparations. Use fresh or dried sprigs with roasted meats (especially lamb, chicken, and pork), roasted potatoes, bread dough (focaccia), and olive oil for dipping. Use fresh sprigs as skewers for grilled meats. A sprig in olive oil for 2 weeks creates an excellent infused oil. Strip leaves from the woody stem and chop finely for seasoning — fresh rosemary leaves are tough when left whole but excellent when minced fine.