Castor aralia Plant Care

Castor aralia (Kalopanax septemlobus) belongs to the Araliaceae family within the Kalopanax genus. Castor aralia is native to northeastern Asia, from Sakhalin and Japan west to southwestern China. Castor aralia is also known as Seven-lobed castor aralia, Korean castor aralia, Tree aralia.

Castor aralia displays a tall, upright tree growth habit, reaching up to 30 ft tall with a spread of approximately 15 ft. Castor aralia produces small white flowers in umbrella-shaped clusters.

Leaf size: approximately 12 inches.

Water a young or newly planted Castor aralia 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.

Castor aralia thrives in partial shade to full sun.

Kalopanax septemlobus tolerates temperatures of 50–85°F. Castor aralia prefers humidity levels of 40–70%.

Rich, well-draining soil with added organic matter like compost or peat moss. Good drainage is essential for Castor aralia to prevent waterlogging, which leads to root rot and fungal issues.

Feed Castor aralia 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 partial shade to full sun and rich, well-draining soil with added organic matter like compost or peat moss. Avoid low spots where water collects after rain.

Castor aralia 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.

Castor aralia can spread to about 15 ft (4.6 m) and reach about 30 ft (9 m) tall. Space plants about 15 ft (4.6 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 tree spacing calculator.

Prune Castor aralia 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.

Castor aralia 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.

Castor aralia can be propagated through seeds, root cuttings.

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

Castor aralia is susceptible to spider mites, scale insects. 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.

Castor aralia grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Castor aralia is native to northeastern Asia, from Sakhalin and Japan west to southwestern China. In cooler regions, grow Castor aralia as a houseplant or bring it indoors before the first frost.