Herb · Lamiaceae
Rosemary
Salvia rosmarinus
Give it full sun and fast-draining soil, then water rarely, and this Mediterranean herb keeps giving for years.
Full sun
Every 7–14 days
USDA 7–11
2–6 ft · 0.6–1.8 m
Overview
Rosemary is a woody evergreen herb from the dry, sunny hills of the Mediterranean, and it never forgets where it comes from. It belongs to the mint family, yet it wants nothing to do with the rich, damp ground its cousins enjoy. Give it sun, grit, and a long dry leash, and it grows into a fragrant shrub you can clip for the kitchen all year.
The plant is a perennial that lives for years in the right spot, building up gnarled, woody stems clothed in narrow, needle-like leaves. Small blue flowers, sometimes pink or white, open in late winter and spring. In zones 7 through 11 it can stay outdoors year-round, and elsewhere it rides out the cold in a pot brought inside.
Few herbs are this forgiving once you grasp the one rule that matters. Rosemary is killed far more often by kindness than by neglect, drowned in soggy soil by a well-meaning gardener. Plant it lean, water it sparingly, and it asks for almost nothing else.
Care
The short version: full sun and sharp drainage, with water only once the soil has dried well down. Feed it lightly if at all, give it room for air to move, and keep it on the dry side year-round.
Light
Rosemary wants full sun, the more the better, at least 6 to 8 hours a day. It will limp along in part shade, but the growth turns thin and leggy and the flavor fades. Indoors, give it the brightest window you have.
Water
This is where most rosemary dies. Let the top half of the soil dry out before you water again, roughly every 7 to 14 days, and ease off further once the plant is established. Soggy roots are the single biggest threat, so when in doubt, wait.
Soil
Plant in light, sandy, sharply drained soil. Rosemary takes poor and rocky ground in stride but rots in heavy clay, so dig in grit or sand if your soil holds water. A pH of 6.5 to 7.0, near neutral, suits it best.
Temperature
Rosemary handles a wide range, from about 10°F to 86°F (-12°C to 30°C), though hardiness varies by cultivar. Hard freezes can kill tender types outright, so in cold zones grow a hardy selection or move pots indoors for winter.
Humidity
It prefers low humidity, around 30% to 50%, in keeping with its dry-country roots. Damp, stagnant air invites powdery mildew, so good airflow matters far more than any moisture you might add.
Feeding
Rosemary is a light feeder and tastes best when it's a little hungry. A single light dose of balanced fertilizer or compost in spring is plenty. Pile on more and you trade fragrance and flavor for soft, sappy growth.
Pruning
Trim lightly after flowering and harvest sprigs through the season to keep the plant bushy and shapely. The one hard rule: don't cut back into old leafless wood, which is slow to sprout again and may not come back at all.
Repotting
Move container plants up a size every 1 to 2 years, or whenever roots circle the pot, water drains through in seconds, or new growth stalls. Use a gritty, fast-draining mix and a pot with real drainage holes.
Size & spacing
24–71 in (60–180 cm) tall
When to plant
Rosemary runs on a slow clock. Seed sown indoors in late winter is hit or miss, so most gardeners set out plants once frost has passed in spring. In mild climates you can snip sprigs the year round, and the small blue flowers open from late winter into spring.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 10-12 weeks before last spring frost (germination is slow and erratic)
- Plant: after danger of frost has passed in spring
- Harvest: Small blue (occasionally pink or white) flowers in late winter to spring; leafy sprigs can be harvested year-round in mild climates.
Hardiness
USDA hardiness zones: 7–11
Temperature: down to -18°C
Troubleshooting
Almost every rosemary problem traces back to one of two things: too much water at the roots or too little air around the leaves. Read the early signs and you can step in before the plant slides. Match what you see below, then act while it still helps.
A plant that wilts and yellows even though the soil stays wet
When rosemary collapses in damp soil, the cause is root rot from overwatering or poor drainage, not thirst. Dig down and you'll find soft, brown roots that smell sour. Stop watering, repot into a gritty, fast-draining mix, and take a few healthy cuttings in case the plant doesn't pull through.
Fix:
- Stop watering and allow soil to dry
- Repot into fast-draining gritty mix and trim rotted roots
- Take healthy stem cuttings as a backup if the plant is failing
Fine webbing and a dull, speckled look to the leaves
Faint webbing and pale stippling point to spider mites, which hit indoor and stressed plants hardest in dry winter air. Turn a leaf over and you'll spot the tiny mites moving among the threads. Rinse the foliage hard, follow up with insecticidal soap or horticultural oil, and give the plant more air.
Fix:
- Rinse foliage with a strong stream of water
- Apply insecticidal soap or horticultural oil
- Increase airflow and reduce plant stress
Brittle, brown stems that drop their leaves after a hard winter
Bare, brittle wood after cold weather is winterkill, and it lands hardest on tender cultivars in marginal zones. Scratch the bark to tell the difference: live wood is green underneath, dead wood is dry and brown. Cut the dead stems back to living tissue in spring and let the plant push fresh growth from what survived.
Fix:
- Prune out dead wood back to living tissue in spring
- Allow plant to regrow from healthy stems
Dusty white film coating the leaves
This is powdery mildew, a fungus that settles in when air sits still around the plant. It shows up most on crowded indoor rosemary in stale winter air. Open up the spacing, drop the humidity, and pull off the worst of the coated foliage.
Fix:
- Improve air circulation and spacing
- Reduce humidity and avoid overhead watering
- Remove and discard affected foliage
Toxicity
Good news for households with pets and small children: rosemary is non-toxic all the way around. The ASPCA lists it as safe for cats, dogs, and horses, and the same culinary herb is fine on your own plate. The only thing to keep apart is the concentrated essential oil, which is a separate product and not for eating.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Rosemary is safe for cats, and the ASPCA lists it among its non-toxic plants. A curious nibble does no harm, though most cats aren't drawn to the strong scent.
Dogs None
Dogs can chew the leaves without trouble, and the herb sometimes turns up in pet foods as a natural preservative. Only an unusually large helping might bring on a mild, passing stomach upset.
Horses Safe
Horses can graze rosemary safely. The aromatic foliage isn't a favorite, so they rarely eat more than a taste.
Rabbits Safe
Fresh rosemary is fine for rabbits in small amounts as part of a varied diet. Hay and greens should still make up the bulk of what they eat.
Livestock Safe
Goats, sheep, and cattle can browse rosemary with no ill effect. The pungent leaves tend to keep most stock from eating much of it anyway.
Birds Safe
The herb poses no danger to backyard hens or pet birds. A sprig in the run is harmless, even if it mostly goes ignored.
People Safe
Rosemary is a kitchen staple, safe to cook with and eat for adults and children alike. The one thing to keep apart is the concentrated essential oil, which is a different product and not for eating.
Highly concentrated rosemary essential oil is a separate product that can irritate skin or be harmful if ingested in quantity, but the culinary herb and growing plant are non-toxic.
Varieties
Rosemary comes in a range of forms, from low trailing mats to tall upright shrubs, and a few cultivars matter most when you're choosing one for cold or for cooking.
Arp
One of the most cold-hardy cultivars, riding out colder winters than rosemary usually can.
Hill Hardy
An upright, cold-tolerant selection that holds up in marginal northern zones where most rosemary struggles.
Tuscan Blue
A vigorous upright grower with deep blue flowers, favored both for cooking and for clipping into low hedges.
Prostratus
A low, trailing groundcover form that spills over walls and pots but takes cold less well than the upright types.
How to propagate
Stem cuttingsEasy
Spring to summer from softwood or semi-ripe growth · 4-8 weeks to root
Cuttings are the surest way to get more rosemary, and most gardeners stick with them. Take 8 to 15 cm pieces of soft or half-ripe spring or summer growth, strip the lower leaves, and set them in a gritty, well-drained medium, where they put down roots in 4 to 8 weeks.
SeedDemanding
Indoors 10-12 weeks before last frost · Several weeks to germinate, then a full season to establish
Starting from seed tests your patience. Sow indoors 10 to 12 weeks before the last frost, but expect slow, scattered sprouting and a poor strike rate, with weeks to germinate and a full season before plants establish. That's why most growers reach for cuttings instead.
Myths
Rosemary needs frequent watering to stay healthy.
Once it has settled in, rosemary handles drought with ease and asks for very little water. Overwatering and soggy soil kill it far more often than dry spells ever do.
The rosemary plant is toxic to pets because rosemary oil can be harmful.
The ASPCA lists the growing plant and culinary herb as non-toxic to cats, dogs, and horses. Only the concentrated essential oil, a separate product, carries any irritation risk, and that's not what your pet meets in the garden or on the plate.