Bornean ironwood Plant Care

Bornean ironwood (Eusideroxylon zwageri) belongs to the Lauraceae family within the Eusideroxylon genus. Bornean ironwood is native to Borneo and Sumatra. Bornean ironwood is also known as Billian.

Bornean ironwood displays a tall, evergreen tree growth habit, reaching up to 50 ft tall with a spread of approximately 20 ft. Bornean ironwood produces small, inconspicuous flowers.

Leaf size: approximately 6 inches.

Water a young or newly planted Bornean ironwood 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.

Bornean ironwood thrives in partial to full sun.

Eusideroxylon zwageri tolerates temperatures of 65–80°F. Bornean ironwood prefers humidity levels of 50–70%. 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 Bornean ironwood to prevent waterlogging, which leads to root rot and fungal issues.

Feed Bornean ironwood 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 partial to full sun and well-draining loamy soil with added organic matter for moisture retention. Avoid low spots where water collects after rain.

Bornean ironwood 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.

Bornean ironwood can spread to about 20 ft (6.1 m) and reach about 50 ft (15 m) tall. Space plants about 20 ft (6.1 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 Bornean ironwood 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.

Bornean ironwood 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.

Bornean ironwood can be propagated through seeds, stem cuttings.

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Bornean ironwood is susceptible to 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.

Bornean ironwood grows outdoors in USDA Zone 13b. It survives winters down to planting zone 13b. Bornean ironwood is native to Borneo and Sumatra. In cooler regions, grow Bornean ironwood as a houseplant or bring it indoors before the first frost.