Grevilleas are sometimes known as spider flowers due to the flower form of some of the species. The genus Grevillea are over 300 species and belongs to the protea family (Proteaceae). Most are endemic to Australia with some occurring in New Guinea, New Caledonia, Sulawesi and Vanuatu. The name, Grevillea, is in honour of Sir Charles Greville who was one of the founders of the Royal Horticultural Society.
Grevilleas are evergreens with distinctive flower clusters. As well as the spider-like flower, some have flowers like a toothbrush while others have large brushes. Most are nectar-rich, making them very attractive to birds, insects and animals, all of which act as pollinators. There is now a good selection of hybrid cultivars.
An example of a grevillea with toothbrush-type flowers is Grevillea hookeriana or, not surprisingly, the toothbrush grevillea. It is a large shrub with bright red flowers. It sometimes flowers throughout the year but is most prolific from August to December.
Grevilleas range from groundcovers to tree-size. The prostrate form of Grevillea tridentifera is suited to heavy clay soils and forms a dense groundcover with finely divided light green leaves. Scented cream flowers form in dense clusters, on (often) upright branches from August to November. The upright branches should be removed after flowering to retain prostrate growth habit.
Grevillea brownii is another showy, low-growing plant, endemic to Western Australia. There are also taller forms in cultivation. Clusters of very bright red flowers appear mainly from May to November. This is an ideal choice as a groundcover under other shrubs. It is also a good choice for sandy soils.
Grevillea confertifolia, also known as Grampians Grevillea or Strawberry Grevillea appears in both prostrate and erect forms. It has narrow, pointed leaves and is adaptable to a range of conditions including heavy, wet soil.
The Grey Spider-flower (Grevillea buxifolia) has flowers of an unusual grey and brown combination. The new growth is a rusty colour and the leaves are oval and hairy. It is suited to a semi-shaded position and is frost-hardy.
Slightly larger, growing to around 1.5 metres, is Grevillea speciosa or the Red Spider-flower which is endemic to New South Wales. The bright red spider flowers appear in wheel-like heads mainly from June to December. If pruned regularly, it will retain its compact shape.
The Lavender Grevillea (Grevillea lavandulacea) grows to 2.5m and has grey-green, needle-like foliage. It has clusters of bright pink to red flowers throughout the year. It is an adaptable and widely cultivated species which prefers a warm, well-drained position. It is a good choice for alkaline soils and will cope with prolonged dry periods.
The Blue grevillea (Grevillea shiressii) is a favourite of nectar-seeking birds. The bluish-green flowers appear mainly from July to December. It is a quick growing, bushy plant suited to sand or gravelly soils. Grevillea asparagoides is another favourite with birds, providing nesting sites and nectar for small native species. The shrub has many branches and the leaves divide into stiff, narrow segments.
One of the taller species is Grevillea barklyana which can reach 5 metres or more. It has pale pink toothbrush flower heads, does well in shaded situations and is frost-hardy. It is a quick growing plant.
One of the tallest of the grevilleas is the Silky Oak or Grevillea robusta. This may grow as tall as 40 metres in its native Queensland habitat. Although the silky oak may initially take some years to flower, it then provides a striking display of bright orange flowers and makes a magnificent landscape tree. Overseas, it has also found a new career as an indoor plant.
Most grevilleas prefer an open sunny position, preferably on freely draining loamy soils. Many thrive in phosphorous deficient soils. They are found over a wide range of climatic conditions. Some have a heady, sweet fragrance, some are short-lived, some have unique floral clusters. All are beautiful.
