Rosemary (Salvia rosmarinus) is an evergreen shrub with aromatic leaves and small mauve, blue, pink or white flowers. It likes a warm, sunny location with light, free-draining soil, and is also happy in containers. It copes well in poor soil and exposed or coastal sites. Originally from Mediterranean climes, rosemary is hardy through most of the UK can tolerating temperatures down to -10 to -5°C (14 to 23°F). It may need some winter protection in colder areas of the UK or frost-prone sites.
Rosemary is drought-tolerant once established and needs little maintenance, apart from clipping annually to keep it compact and bushy. Left unpruned, it can become straggly and bare at the base. Even with regular trimming, it is often best to replace rosemary every five years or so with a new young plant, and luckily it’s very easy to grow from cuttings.
Rosemary is a type of sage, so is ideal for growing alongside other sages and similar shrubby Mediterranean herbs, such as lavender, thyme and hyssop. It makes an attractive centrepiece for a herb garden or herb container and earns its keep in flower borders by providing year-round evergreen structure and scent. Pruned annually, it’s great where space is tight, such as in small sunny courtyards, patios and containers. The flowers, in spring and summer, are popular with bees and other pollinating insects.
Month by Month
The most widely grown rosemary is Salvia rosmarinus. It has pale blue flowers and aromatic leaves that are ideal for many culinary uses. You can grow it simply as an attractive, aromatic shrub.
There are also many varieties to choose from, varying in size, flower colour and style of growth. Some are compact, others tall and upright or low and trailing. Flowers can range in colour from white to pale pink, mauve, purple and blue. Growing several different varieties together can create attractive contrasts. All the various types of rosemary like similarly warm sunny sites with free-draining soil.
To help you choose, why not visit the herb collections at RHS gardens, where you’ll find all kinds of herbs, including many types of rosemary. You can see how they’re grown, compare the varieties and aromas, and pick up useful growing tips. Alternatively, visit a herb nursery to explore the range of varieties on offer.
What and where to buy
Rosemary plants are widely sold by gardening retailers all year round, from small plug plants (recently rooted cuttings) up to well-established shrubs in 2 litre pots. Young plants are even sold in most supermarkets.
For the widest choice of varieties, try herb nurseries and larger plant retailers.
Seeds are also available from garden centres and seed retailers.
Rosemary is usually grown by buying young plants or by rooting cuttings. It likes a warm sunny spot and light free-draining soil. It’s easy to plant and should settle in quickly.
Rosemary can be grown from seed, but germination is often slow and plants will take several years to grow large enough to start harvesting. It’s much quicker and easier to start with bought plants or cuttings (see below).
However, if you do wish to grow from seed, start them off indoors in spring.
Thin out the seedlings into individual pots once large enough to handle, then keep in a warm, bright spot and water regularly. They can be planted outside once they’re at least 10cm (4in) tall.
Choose a planting site with light, well-drained soil. Rosemary hates having wet roots, especially in winter. So if you have heavy soil, plant rosemary in raised beds, where drainage will be better, or in containers. Space rosemary plants at least 45cm (18in) apart.
The best time to plant rosemary is in spring, once the soil is starting to warm up. However, it can be planted right through to early autumn in mild weather. If you plant it in summer, avoid hot spells and water regularly until it’s well rooted in.
Rosemary is very easy to grow and needs little maintenance once established in a warm sunny spot with free-draining soil.
Rosemary is fairly drought tolerant, but new plants should be watered regularly for at least the first summer. Established plants only require watering in long spells of hot dry weather.
Plants in containers need regular watering, especially in summer, as the compost will dry out very quickly.
Apply a thick layer of mulch, such as garden compost or gravel, around the base of rosemary in autumn, to protect the roots from winter cold. If you're using garden compost, leave a gap around the base of the stem to avoid rotting. See our guide to mulching.
Rosemary growing in the ground doesn’t need feeding and should thrive even in poor soil. But rosemary in a container should be given a balanced fertiliser annually after it’s finished flowering.
To keep rosemary compact and encourage fresh young foliage, trim it back lightly every year after the flowers fade, but avoid cutting back into old wood.
Rosemary is generally hardy to -10 to 5°C (14 to 23°F), especially older, well-established plants. Still, it’s worth applying a thick mulch in autumn to help insulate the roots – especially around younger plants or in colder locations and frost-prone sites. You can also cover plants with fleece whenever harsh frosts are forecast.
Plants in containers are more vulnerable to cold, so ideally move them to a sheltered spot over winter or cover them with fleece. Cold, wet compost can cause rosemary’s roots to rot and die.
Rosemary is easy to grow from semi-ripe cuttings in late summer and heel cuttings in spring. Low-growing stems can also be pegged into the ground to root and form a new plant – see our guide to layering.
The leaves can be used fresh or dried for later use.
To dry rosemary, hang up sprigs in a warm, dark, well-ventilated place. When fully dried, strip off the leaves and store in an air-tight jar.
Rosemary can be used to flavour all kinds of dishes, from stews to fish and meat, as well as bread, pasta and much more. It goes particularly with roast lamb. Sprigs can also be used to infuse olive oil. Rosemary tea is said to aid digestion.
Rosemary is usually robust and healthy when grown in suitable warm, sunny, well-drained conditions.
Waterlogging and severe cold can cause problems:
Wet soil or potting compost, especially in winter, can cause roots to rot and die, so ensure there is always good drainage. Plant in raised beds or containers if your soil is heavy
Low temperatures and harsh frosts can damage the shoots or even kill young plants, so cover with fleece in cold spells. To protect the roots, add a thick layer of mulch over the root zone in autumn. The roots of potted plants are particularly vulnerable to cold, so move them to a more sheltered spot over winter
Few pests trouble rosemary, apart from:
Scale insects – which can weaken growth and lead to black sooty mould on the leaves
Rosemary beetles – both the larvae and green-striped metallic-looking beetles eat the leaves
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