Grevillea-robusta

Silk Oak

Common name(s): Silk Oak, Australian Silky Oak

Scientific name: Grevillea robusta

Plant family: Proteaceae

Origin: Australia, Southeast Queensland to New South Wales

Description: Tall tree up to 50 feet and a 30 foot plus spread. Thick trunk with heavy branches. The trunk is unusual with the crisscross of deep furrows. Leaves up to 6 – 13 inches long with multiple leaflets creating feather like appearance. Leaves are thick, dark green above and silver-gray below. Flowers are clusters of yellow-orange with fruit in small round, depressed seed pod.

Growing Conditions: Grows best in full sun with a lot of area to grow. Do not put near buildings. Once established it is drought tolerant. Soil varies from sand, clay and loam, some moisture and well drained. It seems to be tolerant of frost down to 17°F. It may be affected by caterpillars or root rot.

Wildlife: Attracts variety of wildlife form bees, insects, butterflies and hummingbirds.

Relation to Nehrling Gardens: Donated by Leu Botanical Gardens and planted in 2021.

Location in Gardens: Zone 2

Additional Information: As a fast growing tree it has become in some areas in Australia as invasive, crowding out other trees and taking over. This tree is considered an environmental weed in New South Wales and plant invasive of concern. It has currently naturalized in Lord Howe Island.
In Florida, IFAS (Institute of Florida Agriculture Services) has been monitoring the level of spread of the Silk Oak for North, Central and South Florida.