Rosemary is the woody, evergreen herb of roast dinners and Mediterranean cooking — needle-like leaves with a piney, resinous scent, on a shrub that can live for years and grow into a small bush. It is a perennial, not an annual like basil, and once established it needs almost nothing: sun, sharp drainage, and to be left alone. The gardener who kills rosemary almost always does it with kindness — too much water.
Rosemary takes 90–120 days to reach a useful size from seed, which is why most gardeners buy a plant or take a cutting instead — seed is slow, taking 14–28 days just to germinate, and the plant grows slowly in its first year. But a rosemary bought once can last a decade. This guide covers growing from seed or cutting, the drainage that matters more than anything, pruning, and harvesting through the year.
Rosemary at a glance
| Growing factor | What this crop needs |
|---|---|
| Sun | full sun |
| Soil pH | 6.0–7.0 |
| Days to germination | 14–28 |
| Days to maturity | 90–120 |
| Spacing | 24–36 inches |
| Water needs | low |
| Cold tolerance | tender |
| Family | Lamiaceae |
Starting seeds
Rosemary seed is best started indoors. Sow in trays or modules filled with fine seed compost, barely covering the seed, and keep the tray warm and moist — germination takes 14–28 days. Give seedlings as much light as you can once they appear. Our seed-starting calculator can work out your sowing date from your last frost, and the germination-time calculator helps you plan around the 14–28-day germination window.
Because this is a tender crop, timing follows the frost: in Zones 3–6 start indoors and plant out only once frosts are past and the soil has warmed; in Zones 7–9 the warm season is long and a second sowing is often possible; in Zones 10–13, which are frost-free, grow it through the cooler months with afternoon shade in the hottest weather. Check your dates with our frost-date calculator or the last-first frost lookup — and when in doubt, ask your local extension service.
Rosemary is started indoors from seed, and germination is slow — 14–28 days — with variable results, so sow more than you need. Most gardeners skip seed and grow rosemary from cuttings: take a 10 cm cutting in spring or summer, strip the lower leaves, and root it in gritty compost.
Transplanting and planting out
Harden seedlings off for a week before planting out: put them outside for a few hours a day, increasing the time and exposure, and bring them back in at night. Plant out at the final spacing of 24–36 inches apart, in holes the same depth as the pot. Water each plant in well and mulch around (not against) the stems to hold moisture. Our plant-spacing calculator shows how many plants fit your bed at 24–36-inch spacing.
Soil and feeding
Rosemary grows best in soil with a pH of 6.0–7.0, so test your soil before you plant — a cheap test kit tells you more than guessing ever will. Work in a little compost to improve structure, but keep the soil lean — herbs prefer soil that is not over-rich — and make sure the bed drains freely. Our soil-volume calculator and raised-bed soil calculator work out how much soil or compost your bed needs.
Feed lightly: herbs grown in soil that is too rich produce lots of soft leaf with diluted flavour. A little compost at planting time is usually enough, with at most a light feed in spring. Our fertiliser calculator works out how much to apply if your soil is genuinely poor.
Rosemary wants poor, sharp, well-drained soil with a pH of 6.0–7.0 — it grows in rocky Mediterranean hillsides, not in rich garden loam. Dig in grit or coarse sand rather than compost if your soil is heavy, and do not feed it: rich soil makes soft, sappy growth that is less flavoursome and more frost-tender.
Watering
This crop prefers life on the dry side. Water only when the soil has dried out, and then water deeply rather than little and often. Overwatering is the most common way to kill it — wet roots rot, and damp foliage invites mildew. In containers, let the pot dry between waterings and always empty the saucer. Our watering calculator gives a starting point for your bed size and soil, and the watering schedule generator can build a routine around it.
Sunlight and temperature
Give Rosemary full sun — at least six hours of direct sun a day, and more is better in most zones. Sun drives flavour and yield in this crop, and plants in shade stay leggy and unproductive. Our sunlight calculator can check whether your spot gets enough sun.
It is tender, so cold is the enemy: a single frost can finish it. Wait until frosts are past and the soil feels warm before planting out, and keep fleece or cloches handy for a late cold snap. In warm zones it will keep producing until the first cold nights of autumn.
Pests and diseases
The pests and diseases to watch for with Rosemary are aphids, spider mites and whiteflies.
Aphids cluster on tender new growth and under leaves, sucking sap and leaving sticky honeydew.
Spider mites are tiny, thrive in hot dry conditions, and leave fine webbing and speckled leaves.
Whiteflies cloud up from the undersides of leaves when disturbed.
Prevention beats cure: rotate crops so the same family does not grow in the same bed year after year, clear debris at the end of the season, and inspect the undersides of leaves weekly. Our pest identifier helper can help you name a pest from its damage, and the plant-disease checker can narrow down a leaf problem.
Companion plants
Good companions for Rosemary are tomatoes, peppers, marigolds and cabbage.
Tomatoes share this plant's love of sun and rich soil, and the pairing works well when both get enough space and airflow.
Peppers enjoy the same warm, sunny bed and similar watering, so they make a natural neighbour.
Marigolds are the classic companion: their roots and scent deter several soil pests, and their flowers bring in pollinators and beneficial insects.
Cabbage shares similar soil and water needs, and planting herbs nearby helps confuse the cabbage white butterfly.
Plant companions in the same bed rather than in a separate corner — that is how they do their work. Our companion-planting finder can suggest more pairings for your bed.
Harvesting
Rosemary is ready to harvest about 90–120 days after sowing, but a plant grown from a cutting is usable sooner — pick a few sprigs once it is established and growing strongly. Cut sprigs with secateurs, taking the tips of stems: this doubles as pruning and keeps the plant bushy. Harvest all year round — rosemary is evergreen — but pick in the morning, when the oils are strongest, and never take more than a third of the plant at once.
Rosemary dries beautifully, unlike basil: hang bunches upside down in a warm, airy place, then strip the needles into a jar. It also freezes well in oil. In spring, prune lightly after flowering to keep the plant compact — never cut into old, bare wood, because rosemary does not regrow from it. An unpruned rosemary becomes woody and leggy; a lightly pruned one stays dense and productive for years.
Common problems and fixes
| Problem | Likely cause | Fix |
|---|---|---|
| Plant dies over winter | cold and wet together | Grow in a pot and shelter for winter, or plant against a warm wall in sharp drainage. |
| Leaves turn brown and drop | root rot from overwatering | Stop watering, improve drainage, and repot into gritty compost if needed. |
| Plant becomes woody and leggy | never pruned, or pruned into old wood | Prune lightly each spring, cutting only green growth. |
Plant dies over winter
Likely cause: cold and wet together. Rosemary rarely dies of cold alone — it dies of cold and wet together. Wet roots in freezing weather rot, and the plant collapses in spring.
Leaves turn brown and drop
Likely cause: root rot from overwatering. Brown, dropping leaves on rosemary usually mean the roots are rotting in wet soil. Stop watering immediately, check that the pot drains, and if the plant is in the ground, improve drainage or move it to a raised bed.
Plant becomes woody and leggy
Likely cause: never pruned, or pruned into old wood. Rosemary that is never pruned becomes a woody, leggy shrub with bare stems. Prune lightly every spring after flowering, cutting back the green tips to keep it compact — but never cut into old, bare wood, because rosemary does not sprout from it.
Frequently asked questions
How long does rosemary take to grow?
Rosemary takes 90–120 days from seed to a usable plant, and seed germination alone takes 14–28 days. That is why most gardeners buy a plant or grow from cuttings, which establish much faster.
Is rosemary hard to grow?
No — rosemary is one of the easiest herbs once established, as long as it has sun and sharp drainage. The commonest mistake is overwatering: rosemary prefers to be dry.
Can rosemary survive winter?
It depends on your zone and your soil. Rosemary is tender and hard frosts can kill it, especially in wet soil.
Why is my rosemary dying?
Almost always overwatering or winter wet. Rosemary hates wet roots: check drainage, let the soil dry between waterings, and in winter keep it as dry as possible.