Box Poison Plant Care

Box Poison (Gastrolobium stenophyllum) belongs to the Fabaceae family within the Gastrolobium genus. Box Poison is native to Western Australia.

Box Poison displays an upright, bushy shrub growth habit, reaching up to 4 ft tall with a spread of approximately 3 ft. Box Poison produces brightly colored pea-like flowers in clusters.

Leaf size: approximately 2 inches.

Water a young or newly planted Box Poison every 7–14 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established shrubs mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Box Poison thrives in full sun to partial shade.

Gastrolobium stenophyllum tolerates temperatures of 60–80°F. Box Poison prefers humidity levels of 40–60%.

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

Feed Box Poison every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established shrubs 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.

Box Poison is suited to USDA Zone 13a.

Plant container-grown or balled-and-burlapped shrubs in spring or early autumn, setting the root flare at soil level, and water well after planting.

Box Poison can spread to about 3 ft (0.9 m) and reach about 4 ft (1 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 plant spacing calculator.

Prune Box Poison 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 shrub in one year.

Box Poison 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.

Box Poison can be propagated through seeds, cuttings. Similar propagation techniques also apply to gastrolobium acrocaroli plant care, which shares the same genus.

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Box Poison is susceptible to aphids, caterpillars, 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.

Box Poison grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. Box Poison is native to Western Australia. In cooler regions, grow Box Poison as a houseplant or bring it indoors before the first frost.