Grevillea : Greenhouse Plants
C – cool, minimum of 7°C (45°F) / W – warm, minimum of 13°C (55°F)
The plant that will spring into most people’s minds is the elegant Silk Oak, Grevillea robusta, from New South Wales which is widely raised from seed and used as a foliage plant with great effect, especially as a tall plant for greenhouse displays. The leaves are soft and-like but I have never seen this plant flower under glass even if grown to 9 m (15 ft) tall. This is by far the easiest to cultivate and does not seem fussy as to . I grow mine in a loam-based in cool conditions. More difficult to grow are the species that will reward your efforts with curious flowers. G. banksii from Queensland is very choice, making a shrub of 2 m (7 ft) tall if planted out. It has silver-grey leaves which are silky beneath and red flowers. Seed will germinate well in late spring at a temperature of 15°C (60°F). They need a lime-free compost and seem to dislike phosphates in the compost. After germination they need looking after very carefully, air circulation being important. Prick them out just as the proper leaves begin to show.
Cuttings are possible, if difficult. I have found midsummer as good a time to take them as any; try to take side shoots 10 cm (4 in) long with a heel if possible. They do not like the close atmosphere of a propagating case and are best stood on the greenhouse staging. G. Sulphurea with its small yellow flowers and G. rosmarinifolia with red flowers are good subjects for the cool or frost free house. You will be relieved to know that they are easier to care for and propagate than G. banksii.