Blackboy Plant Care

Blackboy (Kingia australis) belongs to the Dasypogonaceae family within the Kingia genus. Blackboy is also known as Australian Grass Tree.

Blackboy displays a tall, single-stemmed growth habit, reaching up to 10 ft tall with a spread of approximately 2 ft. Blackboy produces cream-colored flowers in a dense spike.

Water a young or newly planted Blackboy every 14–21 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.

Blackboy thrives in full sun.

Kingia australis tolerates temperatures of 50–85°F. Blackboy prefers humidity levels of 40–70%.

Well-draining sandy soil with low organic content. Good drainage is essential for Blackboy to prevent waterlogging, which leads to root rot and fungal issues.

Choose a spot with full sun and well-draining sandy soil with low organic content. Avoid low spots where water collects after rain.

Blackboy 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.

Blackboy can spread to about 2 ft (0.6 m) and reach about 10 ft (3 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 tree spacing calculator.

Prune Blackboy 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.

Blackboy 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.

Blackboy can be propagated through seeds.

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Blackboy is susceptible to mealybugs, 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.

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