New Guinea Poplar Plant Care

New Guinea Poplar (Homalanthus novoguineensis) belongs to the Euphorbiaceae family within the Homalanthus genus. New Guinea Poplar is native to Australia and nearby tropical islands in disturbed areas near rainforest. New Guinea Poplar is also known as Native Poplar.

New Guinea Poplar displays a tall, upright shrub growth habit, reaching up to 5 ft tall with a spread of approximately 3 ft. New Guinea Poplar produces small inconspicuous flowers.

Leaf size: approximately 6 inches.

Water a young or newly planted New Guinea Poplar 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.

New Guinea Poplar thrives in bright indirect light. Avoid placing New Guinea Poplar in direct, harsh sunlight for extended periods, as this can scorch the foliage.

Homalanthus novoguineensis tolerates temperatures of 65–80°F. New Guinea Poplar prefers humidity levels of 50–70%. A pebble tray or humidifier helps maintain adequate moisture around the plant.

Well-draining soil mix with added organic matter for moisture retention. Good drainage is essential for New Guinea Poplar to prevent waterlogging, which leads to root rot and fungal issues.

Feed New Guinea Poplar 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 bright indirect light and well-draining soil mix with added organic matter for moisture retention. Avoid low spots where water collects after rain.

New Guinea Poplar is suited to USDA Zone 13b.

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.

New Guinea Poplar can spread to about 3 ft (0.9 m) and reach about 5 ft (2 m) tall. Space plants about 3 ft (0.9 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 New Guinea Poplar 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.

New Guinea Poplar 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.

New Guinea Poplar can be propagated through seeds, stem cuttings. Similar propagation techniques also apply to stinging tree plant care, which shares the same genus.

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

New Guinea Poplar is susceptible to spider mites, scale insects, mealybugs. 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.

New Guinea Poplar grows outdoors in USDA Zone 13b. It survives winters down to planting zone 13b. New Guinea Poplar is native to Australia and nearby tropical islands in disturbed areas near rainforest. In cooler regions, grow New Guinea Poplar as a houseplant or bring it indoors before the first frost.