Rosemary (Rosmarinus officinalis) is a Mediterranean shrub that evolved on rocky, sun-baked hillsides with thin soil and summer drought. Understand that origin and every care decision becomes obvious: it wants conditions that would stress most garden plants. Give it those conditions and a single plant can live for a decade or more, growing into a woody, fragrant shrub that doubles as a landscape specimen.
Where rosemary grows: zones, sun, and soil
Rosemary is reliably winter-hardy in zones 8 through 10. In zone 7, established plants usually survive with some protection, though a hard cold snap below about 10 degrees F can kill them. Cold-hardy cultivars such as 'Arp' and 'Hills Hardy' extend the range into zone 6 with some shelter, but anything north of zone 6 should plan on container culture. For zone hardiness specific to your location, see the rosemary plant profile.
Sun matters enormously. Rosemary growing in partial shade produces weaker, more disease-prone plants with poorer flavor and less essential-oil concentration. A south- or west-facing bed is ideal.
Drainage is the single most important soil factor. Rosemary will rot quickly in waterlogged ground, especially over winter. If your native soil is clay-heavy or slow-draining, amend generously with coarse sand or grit before planting, or build a raised bed. Lean soil with average fertility is fine; rich, heavily fertilized soil produces lush but soft growth that is more susceptible to disease and less flavorful.
Planting: transplants and cuttings, not seed
Starting rosemary from seed is possible but rarely worth the effort. Germination is slow (up to three weeks), viability is low, and seedlings take a long time to reach a usable size. The standard approach is to:
- Buy transplants from a nursery and plant them after your last frost date in spring, or in early fall in zones 8-10 where winters are mild.
- Root stem cuttings from an established plant by taking 3-4 inch cuttings from non-flowering, softwood growth in late spring or early summer. Strip the lower leaves, dip in rooting hormone, and insert into a perlite-heavy mix. They root in 3-4 weeks.
Set transplants at the same depth they were in their nursery container. Do not plant deeper. Space standard upright varieties 2 feet apart; trailing or prostrate types can be spaced a bit closer.
Watering and feeding: less is more
Once established, rosemary is genuinely drought-tolerant. The rule is: water deeply, then let the soil dry completely before watering again. Young transplants need more frequent watering for their first season while roots develop, but as soon as the plant is established, cut back sharply.
Overwatering is the number-one way rosemary dies. Soggy roots invite root rot and powdery mildew, both of which can kill a plant quickly. When in doubt, do not water.
Fertilizer requirements are similarly minimal. Rosemary growing in decent garden soil needs little or no supplemental feeding. A light application of balanced organic fertilizer in early spring is sufficient for in-ground plants. Container plants, which deplete potting mix nutrients faster, benefit from a dilute feed once or twice during the growing season. Avoid high-nitrogen fertilizers, which promote lush growth at the expense of flavor and cold hardiness.
Pruning and harvesting
You can harvest rosemary any time during the growing season by snipping individual stems. A good rule: never remove more than one-third of the plant at any one picking.
For shaping and to keep plants from becoming too woody and open, prune after flowering in spring. Cut back into green wood but not into the thick, mature woody stems, which do not reliably re-sprout. Light, frequent trimming throughout the season keeps the plant compact. A good pair of bypass pruners like the Felco F-2 makes the work easy on woody stems without crushing them.
For a full harvest, cut stems in the morning after dew dries, when essential oil concentration is highest. Strip needles from the lower portion of the stem and use fresh, or dry by hanging in a warm, airy space for 1-2 weeks.
Overwintering: the zone 6-and-below reality
In zones where rosemary cannot survive outdoors, container growing is the practical solution.
Overwintering rosemary in a container
Choose the right pot
Use a terra cotta or well-draining container at least 12 inches wide. Unglazed terra cotta breathes and dries faster than plastic, reducing root rot risk.
Use a lean, gritty mix
Blend potting mix with perlite at roughly 1:1 by volume. Standard potting soil holds too much water for rosemary in the reduced light of indoors.
Bring it in before hard frost
Move the pot indoors when nighttime temperatures consistently approach the low 30s F. Do not wait for a freeze.
Give it maximum light
A south-facing window is the minimum. A supplemental grow light helps enormously in northern winters when window light is weak.
Water sparingly
Indoors in low light, rosemary's water needs drop significantly. Water only when the top inch of mix is completely dry.
Return outdoors after last frost
Harden off gradually over 7-10 days before leaving the plant in full outdoor sun.
Common problems
Rosemary is notably pest- and disease-resistant when grown in the right conditions. Most problems trace back to moisture.
- Root rot: almost always caused by overwatering or poor drainage. The plant wilts and fails to recover with watering. Prevention is far easier than cure: improve drainage at planting. See root rot.
- Powdery mildew: a white coating on leaves, more common in humid climates or when air circulation is poor. Prune for airflow, avoid overhead watering. See powdery mildew.
- Spider mites: sometimes appear on indoor plants in dry winter air. Increase humidity slightly and rinse with water. See spider mites.
- Aphids: occasional, especially on new growth. Knock off with a strong water spray. See aphids.
Companion planting and garden use
Rosemary is a good companion for sage, thyme, and other Mediterranean herbs that share its preference for dry, lean conditions. It is also widely planted near brassicas as a potential pest deterrent, and near basil in the herb garden. See the companion planting guide for more herb pairings.
Is rosemary a perennial or annual?
Rosemary is a perennial shrub, meaning the same plant can live and regrow year after year. However, it is only truly hardy in the ground in USDA zones 7-10. In colder zones it behaves as a tender perennial: grow it in a container and bring it indoors each winter to keep the same plant going from year to year.
Why does my rosemary keep dying?
The most common cause is overwatering combined with poor drainage, which causes root rot. Rosemary evolved in dry, rocky Mediterranean soil and is far more tolerant of drought than of soggy conditions. Check that your pot or bed drains freely, reduce watering frequency, and let the soil dry completely between waterings. Inadequate sun is the second most common cause.
Can rosemary survive winter outdoors?
In zones 8-10, yes, with no special care. In zone 7, established plants often survive with some mulch protection around the root zone after a hard frost hardens the soil. In zone 6, cold-hardy cultivars like 'Arp' can sometimes overwinter in a sheltered, south-facing spot, but survival is not guaranteed. In zones 5 and below, bring rosemary indoors in a container for winter.
When should I harvest rosemary?
You can harvest rosemary any time the plant is actively growing. The best time of day is morning after dew has dried, when essential oil levels are highest. For a full harvest, cut 3-4 inch sprigs from the tips of stems but never remove more than one-third of the plant at a time. New plants should be harvested lightly in their first year while they establish.
Can rosemary grow in a pot indoors?
Yes. Rosemary can grow indoors year-round in a sunny window, though it needs as much direct light as possible and very careful watering (much less than you would expect). The biggest challenge indoors is low humidity combined with overwatering. A south-facing window or a supplemental grow light, lean gritty potting mix, and infrequent watering are the keys to success.
The bottom line
Grow rosemary in the hottest, sunniest, leanest, best-drained spot in your garden and water it sparingly. North of zone 7, plan on a container so you can bring it inside before winter. Get the drainage right and the neglect right, and rosemary will repay you with a fragrant, long-lived shrub that asks for almost nothing.