Swamp Myrtle Plant Care

Swamp Myrtle (Morella interrupta) belongs to the Myricaceae family within the Morella genus. Swamp Myrtle is native to Australia. Swamp Myrtle is also known as Australian Bayberry.

Swamp Myrtle displays an upright, spreading shrub growth habit, reaching up to 6 ft tall with a spread of approximately 8 ft. Swamp Myrtle produces small greenish-yellow catkins.

Leaf size: approximately 3 inches.

Water a young or newly planted Swamp Myrtle 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.

Swamp Myrtle thrives in full sun to partial shade.

Morella interrupta tolerates temperatures of 50–80°F. Swamp Myrtle prefers humidity levels of 40–70%.

Well-draining sandy loam with added organic matter. Good drainage is essential for Swamp Myrtle to prevent waterlogging, which leads to root rot and fungal issues.

Feed Swamp Myrtle every 8 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 sandy loam with added organic matter. Avoid low spots where water collects after rain.

Swamp Myrtle is suited to USDA Zone 12a.

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.

Swamp Myrtle can spread to about 8 ft (2.4 m) and reach about 6 ft (2 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 Swamp 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 tree in one year.

Swamp Myrtle is frost-tender (hardy to USDA zone 12). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Swamp Myrtle can be propagated through seeds, hardwood cuttings.

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

Swamp Myrtle is susceptible to aphids, scale insects, caterpillars. 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.

Swamp Myrtle grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Swamp Myrtle is native to Australia. In cooler regions, grow Swamp Myrtle as a houseplant or bring it indoors before the first frost.