coastal rosemary Plant Care

coastal rosemary (Robsonodendron maritimum) belongs to the Celastraceae family within the Robsonodendron genus. coastal rosemary is native to the coastal regions of South Africa. coastal rosemary is also known as seaside lavender.

coastal rosemary displays a tall, upright tree growth habit, reaching up to 15 ft tall with a spread of approximately 8 ft. coastal rosemary produces small clusters of white, fragrant flowers.

Leaf size: approximately 6 inches.

Water a young or newly planted coastal rosemary every 7–14 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established trees mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

coastal rosemary thrives in full sun to partial shade.

Robsonodendron maritimum tolerates temperatures of 60–85°F. coastal rosemary prefers humidity levels of 50–80%. A pebble tray or humidifier helps maintain adequate moisture around the plant.

Well-draining loamy soil with added organic matter for moisture retention. Good drainage is essential for coastal rosemary to prevent waterlogging, which leads to root rot and fungal issues.

Feed coastal rosemary every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established trees in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with full sun to partial shade and well-draining loamy soil with added organic matter for moisture retention. Avoid low spots where water collects after rain.

coastal rosemary is suited to USDA Zone 9b – 11b.

Plant container-grown or balled-and-burlapped trees in spring or early autumn, setting the root flare at soil level, and water well after planting.

coastal rosemary can spread to about 8 ft (2.4 m) and reach about 15 ft (5 m) tall. Space plants about 8 ft (2.4 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the tree spacing calculator.

Prune coastal rosemary while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the tree in one year.

coastal rosemary is frost-tender (hardy to USDA zone 9). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

coastal rosemary can be propagated through seeds, stem cuttings.

See all plants toxic to cats and plants toxic to dogs.

coastal rosemary is susceptible to aphids, scale insects, spider mites. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.

coastal rosemary grows outdoors in USDA Zone 9b – 11b. It survives winters down to planting zone 9b. coastal rosemary is native to the coastal regions of South Africa. In cooler regions, grow coastal rosemary as a houseplant or bring it indoors before the first frost.