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Garden Team Blog

Eucalyptus – an overview from Malcolm Pharoah

By January 31, 2022March 2nd, 2023No Comments

Walking around the garden at this time of year, trees are the dominant feature, and probably the most obvious are the Eucalyptus. There are over 30 species in our collection, some planted as far back as the 1960s and many others from 1980 onwards.

One of the most noticeable is a large upright tree called Eucalyptus nitens or “Silvertop” which is its common name in Australia, where it grows in New South Wales. It can’t be missed as it stands in the middle of the Silver Birch/Eucalyptus grove towering over the others with great sheathes of bark streaming from its trunk. It is in fact the tallest tree in the garden and nearly the Champion tree in Britain. Champion Trees are either the tallest or ones with the widest girth. Ours, when last measured was a foot shorter than the tallest tree, which grows in a forest in Argyll on the south west coast of Scotland.

Eucalyptus are native of Australia and account for nearly 95% of all trees in the whole of the country.   Most grow in the South Eastern corner of the country from Queensland down through Sydney and Canberra to Melbourne and Adelade. These together with other species on the island of Tasmania are the hardiest and most suitable for growing in Britain. All have white flowers, flowering at different times of the year according to species and are great for bees who collect the pollen for making honey. In Western Australia, the Eucalyptus species here are much more tolerant of hot dry conditions, not suitable for Britain but produce spectacular pink or red flowers.

Many plants in Australia go through two stages of foliage, Juvenile and Adult. In fact Eucalyptus also has an intermediate stage. The juvenile foliage is generally round and glaucous (blue) and as the tree ages the adult foliage emerges which is generally sickle shaped looking totally different. Both types of foliage can be seen on trees, if a branch is cut or broken off, the new shoots grow out with juvenile foliage.

Fire, of course is the main threat to the trees in their native Australia as the country suffers from hot dry conditions most years but the trees have evolved to cope with this as their hard seed pods need the heat of the fires to open the capsules to release the seed and so establish new plants.   Most species also have a lignotuber situated at the base of the trunk so that when the tree is burnt or cut down, new shoots can emerge and grow forming a new trunk in time.

In this country Eucalyptus plants grow fast, in fact the trunk grows quicker than the roots, and if a trunk is allowed to grow straight up it becomes a target for winds and can be blown over. We recommend cutting the trunk back by two thirds each spring for the first four or five years, as that way the roots get established and so can support the tree throughout its life.

The recent storms of the past two weeks with winds of nearly 100mph here has blown over several trees including Eucalyptus, however “Silvertop” is still standing tall and looking forward to welcoming visitors for the coming season!

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