Swan River myrtle Plant Care

Swan River myrtle (Hypocalymma robustum) belongs to the Myrtaceae family within the Hypocalymma genus. Swan River myrtle is native to the south-west of Western Australia.

Swan River myrtle displays a compact shrub with dense foliage growth habit, reaching up to 3 ft tall with a spread of approximately 2 ft. Swan River myrtle produces small clusters of white or pink flowers.

Leaf size: approximately 4 inches.

Water a young or newly planted Swan River myrtle every 7–10 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established shrubs mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Swan River myrtle thrives in bright indirect light. Avoid placing Swan River myrtle in direct, harsh sunlight for extended periods, as this can scorch the foliage.

Hypocalymma robustum tolerates temperatures of 60–75°F. Swan River myrtle prefers humidity levels of 50–70%. A pebble tray or humidifier helps maintain adequate moisture around the plant.

Well-draining acidic soil mix with added organic matter like peat moss. Good drainage is essential for Swan River myrtle to prevent waterlogging, which leads to root rot and fungal issues.

Feed Swan River myrtle every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established shrubs 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 bright indirect light and well-draining acidic soil mix with added organic matter like peat moss. Avoid low spots where water collects after rain.

Swan River myrtle is suited to USDA Zone 13a.

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

Swan River myrtle can spread to about 2 ft (0.6 m) and reach about 3 ft (1 m) tall. Space plants about 2 ft (0.6 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 plant spacing calculator.

Prune Swan River myrtle 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 shrub in one year.

Swan River myrtle is frost-tender (hardy to USDA zone 13). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Swan River myrtle can be propagated through softwood cuttings, seeds. Similar propagation techniques also apply to white myrtle plant care, which shares the same genus.

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

Swan River myrtle 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.

Swan River myrtle grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. Swan River myrtle is native to the south-west of Western Australia. In cooler regions, grow Swan River myrtle as a houseplant or bring it indoors before the first frost.