Grevillea the spider flower - Shirley Clemo

The Grevillea is a wild flower of Australia belonging to the Protea family, named after the Greek God Proteus, who had the ability to change his appearance and form, as Grevilleas have done.

The genus Grevillea was named for Charles F Greville (1749-1809), who was president for some time of the Royal Horticultural Society. There are many species-around 280 known - and apart from Australia a few occur in New Guinea, Celebes and New Caledonia. More than half are found in Western Australia but those from the eastern side of that country are easier to grow in our gardens.

There are five inflorescence types :

1. The erect cluster, where flowers are born terminally
2. The toothbrush type, with flowers born terminally in a one sided spike
3. The central inflorescence, with flowers born terminally all around the stem
4. The long, feathery-soft inflorescence
5. The pendant cluster, where flowers are born terminally or along the branch but hang down below the branch.

The striking flowers of these plants always attract attention. Most visitors to our garden at Pine Lodge, St Austell, have never seen or even heard of them before. The structure, and the fact that they have no petals makes them unusual. The coloured calyx is divided into four segments and the anthers are born in the hollows at the ends, while the pistil stands out boldly.

Grevilleas have been grown in this country since the early 1800s. Apart from the species, there are hundreds of hybrids, although only a few are hardy in this country. For the last 10 years I have been raising plants and trying them outside but only those listed have survived. I brought back seed in 1992 of a new hybrid to England and it has withstood the winter of 1996-1997. The temperature here at Pine Lodge dropped to minus 6.5 degrees C (20 decrees F). It is a cross between the upright red form of Grevillea juniperina and the prostrate yellow form and has come true from seed. Named Grevilleas j. "Molongo", it is prostrate, apricot in colour and very vigorous.

The Grevilleas we manage to grow are quite fast growing but they insist on an acid soil-even when taking cuttings, only very ericaceous potting compost should be used. We never feed the Grevilleas in the garden-in the wild they grow in very poor soil. They resent root disturbance, and very careful putting on and planting is advised. I have never found any damage or disease affecting plants grown outside. I have grown plants in part shade, Sun and windy places. All have been tolerant of all conditions, although there has been a little less flowering in shady spots.

The leaf forms of Grevilleas are very diverse,

1. Holly leaf
2. Narrow leaf
3. Oval leaf
4. Saw-tooth leaf
5. Fishbone leaf
6. Needle leaf
7. Twice-lobed
8. Heavily lobed.

Most homes do not possess large gardens these days, so pruning is a must. Grevilleas do not mind being pruned, in fact it keeps them more compact and encourages more flowers, and the plant will live longer. If left unpruned, they tend to be come gaunt and the lower branches unflowering. The best time to prune is after the main flowering season is over, May/June, but they will continue to flower if left. Next year's flowers will be born on the end of the branches. Always use sharp saboteurs to avoid tearing. If Grevilleas go unpruned for many years, they will not take kindly to heavy pruning. It is better to replace with a young plant.

Grevilleas, on the whole, like well-drained soil and a pH of 6 to 7. Most are pollinated in the wild by nectar-feeding birds, and of all the Grevilleas I have grown, I have only ever found seed on one plant, a ground cover Grevillea juniperina, prostrate yellow, perhaps pollinated by a crawling insect.

I find Grevilleas easy to propagate from cuttings. I take heel cuttings in May to get the plant well established before winter's short days and misty weather, which they abhor. I use a root-promoting hormone cutting powder and take 3 inch (7.5 centimetre) cuttings. I have used half by volume vermiculate and sand and half by volume of sand and peat. This year I am propogating in cells. It gives a better survival rate and less root disturbance. When taking cuttings, trim off the lower leaves of the cutting with a sharp knife or pull the needle leaves upwards to stop tearing of the stem. All soft growth or flowers should be removed. Most should produce roots within two months. Some I have noticed only callus and do not produce roots but I have potted them on and they have eventually grown away and produced roots.

If buying imported seeds, I find the most successful way to propagate them is to nick the outside edge of the seed with a razor blade to help water penetration. Others advocate steeping over night in hot water. They need a temperature of around 60-70 degrees F (16-21 degrees C) to germinate. Do not plant deeper than 5 millimetres.

The soil in most parts of our garden is clay but over the years we have added large quantities of spent hops and mushroom compost and the soil is now very fertile and friable. We never use fertilisers because the Grevilleas resent it. We used to use peat until the news of the destruction of the peat bogs became apparent.

Grevilleas for Cornish gardens

The Grevilleas listed here are all hardy in a garden in Cornwall and have all survived minus 6 degrees C (2.6 F)

• Grevillea alpina is a very variable in the wild. The form we grow is pink and white and reaches 0.5 metres (20 inches)
• Grevillea alpina 'Olympic Flame' - is red and can reach 2m (6ft), Very vigorous.
• Grevillea 'Apricot Queen' - is salmon and yellow, rather willowy in growth to 2m (6ft).
• Grevillea 'Canberra Gem' - is similar to 'Olympic Flame' but only half the height, to 1m (3ft)
• Grevillea juniperina 'Molongo' - is really prostrate, very vigorous, with apricot flowers
• Grevillea juniperina 'Prostrate Yellow' - another ground hugger with pale yellow flowers.
• Grevillea juniperina f. suplhurea - grows to 2m (6ft) with yellow flowers
• Grevillea lanigera - there is an upright form but we grow the ground-cover form, with soft dark green leaves, very beautiful foliage with flowers of red and cream.
• Grevillea rosmarinfolia - flowers are normally pink and white but cream and red forms exist, grows to 1 - 1.15 m (3 - 5 ft)
• Grevillea rosmarinfolia 'Jenkinsii' - grey leaves and red flowers, grows to 1m (3ft)
• Grevillea X semperflorens - apricot flowers, willowy form, very dainty looking, grows to 2m (6ft)
• Grevillea thrysoides - grey-ish green leaves with red flowers, grows to height of 1.5 m (5ft)

Shirley and Raymond Clemo hold the National Collection of Grevilleas at Pine Lodge, St Austell

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