Silky Oak Plant Care

Silky Oak (Grevillea robusta) belongs to the Proteaceae family within the Grevillea genus. Silky Oak is also known as Southern Silky Oak, Ivory Silk Oak.

Silky Oak displays an upright, bushy shrub growth habit, reaching up to 6 ft tall with a spread of approximately 4 ft. Silky Oak produces showy clusters of red, pink, or white flowers.

Leaf size: approximately 4 inches.

Water a young or newly planted Silky Oak 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.

Silky Oak thrives in full sun to partial shade.

Grevillea robusta tolerates temperatures of 50–80°F. Silky Oak prefers humidity levels of 40–70%.

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

Feed Silky Oak 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 full sun to partial shade and well-draining sandy loam with added organic matter. Avoid low spots where water collects after rain.

Silky Oak 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.

Silky Oak can spread to about 4 ft (1.2 m) and reach about 6 ft (2 m) tall. Space plants about 4 ft (1.2 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 Silky Oak 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.

Silky Oak 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.

Silky Oak can be propagated through seeds, cuttings. Similar propagation techniques also apply to acacia grevillea plant care, which shares the same genus.

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Silky Oak is susceptible to aphids, scale insects, caterpillars. 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.

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