They are eye-catching, and look harmless enough to anyone who does not know them. But beware. If unpruned, in three or four years a eucalyptus can grow to 20 feet, and in 10 years it could reach a massive 50 or 60 feet. The bright silver leaves will have turned a rather dull greyish- green, and as a final insult, if there is a gale your eucalyptus might easily come crashing down.
The speed at which they grow may be a benefit, of course, if the idea is to hide an unsightly building. But if the aim is to keep the bright silvery leaves, eucalyptuses have to be pruned very carefully.
There are 600 or so different types in Australasia, but about 12 are reliably hardy in this country. In most of these, the juvenile leaves are quite different from the adult ones. They are often silver, coppery- pink, or edged with red, and are very popular with flower-arrangers. But the plant has to be coppiced or pollarded every year to produce these leaves.
Dr James Smart, of Marwood Hill Gardens near Barnstaple in Devon - who grows about 15 different varieties - recommends cutting eucalyptus trees back by about a third to a half every autumn or spring. This will have the advantage of encouraging strong roots, which will help the tree withstand strong winds. After three or four years, the plant can be pollarded at a chosen height, perhaps about six feet, to ensure that it produces the attractive leaves.
Alternatively, the plant can be coppiced, cutting it down to 18 inches or less every spring. It will then produce a mound of new leaves, that can be cut for indoor decoration during the winter, before the whole thing is coppiced again the following spring.
There is a thriving industry - mostly in the West Country - of growers with acres of coppiced eucalyptus producing foliage for the cut-flower trade. The current favourite for this is E parvifolia, which produces small green leaves on red stems and is often seen around Christmas. E gunnii, with its round silver leaves, is also popular. Its leaves preserve well, if they are stood in a mixture of glycerine and water.
Andrew McConnell, of Celyn Vale Nurseries in North Wales, grows 40 different types of eucalyptus and sends out around 100,000 young trees each year. He explained that the ability of a tree to withstand frost depends on how cold the region is where the parent plant grows. Seeds from a tree growing in an area where there are regular cold frosts will produce offspring which can stand equivalent frosts.
Among the hardiest, he says, are E niphophila, which has brightly coloured snakeskin bark, E gunnii, E pauciflora, which also has a mottled trunk, E parvifolia, E perriniana, whose young glaucous leaves encircle the stem, and E coccifera, which has peeling grey-and-white bark.
Celyn Vale Nurseries, Carrog, Corwen, Clwyd LL21 9LD (01490 430671)Reuse content