The cider gum tree,
whose Latin name is
Eucalyptus gunnii
, is part of the Myrtaceae family, like the myrtles (
Myrtus
), the tea tree (
Melaleuca alternifolia
) or the clove tree (
Syzygium aromaticum
) whose fruits give a famous spice: the clove.
What are the origins of the cider gum tree?
Island of Tasmania, south of Australia.
Sacred to local populations, the cider gum tree takes its name from its very sweet sap.
Its introduction in France, like that of other eucalyptus, dates from the middle of the 19th century, first around the Mediterranean, then further north because of its good resistance to cold.
Threatened by farming in its native area, this beautiful tree was classified in 2019
as an “endangered species”
by the International Union for the Conservation of Nature.
What are the characteristics of the cider gum tree?
Because of its imposing size (20 m high at maturity for 10 m wingspan),
E. gunnii
naturally finds its place in sufficiently large gardens or in parks.
Its speed of growth is astonishing since it can reach 10 m in height, only 5 years after its plantation.
Another originality, during the first years of growth, its evergreen and opposite leaves, silvery blue in color, have a rounded shape (3 to 4 cm in diameter).
This earned it its other name of
“Eucalyptus with round leaves”
.
But after a few years, their color changes, verging on green, while they become alternate and gradually lengthen until they reach 8 cm in length.
This " round
" shape can be maintained
by shortening the tree with clumps: it will then keep a spreading and bushy habit as well as its juvenile bark which peels off in whole patches, creating cream-brown patterns.
As with the leaves, the appearance of the trunk and branches changes over time: the color of the bark loses its intensity but still cracks in places, revealing a shaft with shades of yellowish green/grey-pink.
Although discreet, the flowers, creamy white in color and one centimeter wide, attract a large number of pollinators.
Grouped on the branches like small pompoms, they give after fertilization small green fruits then brown when ripe, cup-shaped, which contain the seeds.
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What are the uses of the cider gum tree?
Very popular in gardens and parks for its ornamental qualities, the round-leaved eucalyptus is also used to make dyes from its tannin-rich bark.
From its very aromatic leaves, used once dried to perfume linen, an essential oil is also extracted, with antiseptic and antifungal properties.
Where to plant the cider gum tree?
Flowering period:
August to September.
Fruiting from September to October.
Hardiness
: Round-leaved eucalyptus is resistant to cold (down to -18°C) and heat.
But it happens, between 30 and 40°C that branches break.
Level of difficulty
: Easy.
Soil
:
E. gunnii
likes deep, cool, rich, drained but not too dry soil.
The pH should preferably be neutral, even slightly acidic or calcareous.
Exposure
: Very bright and sunny, sheltered from strong, drying winds to which it is very sensitive.
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How to grow the cider gum tree?
Sowing and planting
:
In our climates, sowing can be done in a terrine or in a pot from the end of September from seeds harvested from the tree, provided that a high temperature (18-24°C) is maintained in a heated greenhouse in winter or under a frame. in spring.
The seeds germinate after about 4 weeks.
Due to their rapid growth, the seedlings must be potted (first potted) quickly enough to avoid the formation of a root bun.
The rich substrate must be kept moist but not excessively to avoid damping off, fungal disease causing the seedlings to rot.
Planting takes place outside periods of frost or hot weather.
Either from March to May or from September to November when the earth is still warm (or warming up) and night temperatures are above 10°C.
In pots, use a classic, rich, well-drained potting mix and a deep container.
In the ground, opt for a mixture half potting soil, half garden soil.
The planting pit should be quite wide and deep, 2 to 3 times the height of the root ball.
It is of course necessary to amend it and water it copiously before and after planting.
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Cultivation management
:
Adding fertilizer is not necessary.
In pots, let the root ball dry out before any further watering.
In the ground, watering will be necessary during the first months to help recovery.
In order to maintain a bushy and bluish silhouette, a training pruning can be practiced at least once a year, at the start of the vegetation, in March.
Do not hesitate to fold short, above the third node of each branch.
If a natural development is preferred, a simple maintenance pruning can be carried out once a year, at the same time, by removing the branches that cross or by lightening the silhouette.
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What are the most common diseases and parasites?
Eucalyptus gunnii
is quite a hardy tree.
However, in Mediterranean regions, it can be subject to certain pests, such as longhorn beetles, weevils and psyllids.
This tree can also be affected by diseases such as gall.
These are blisters present on the leaves, caused by the larvae of different species of insects (
Ophelimus eucalypti
,
Ophelimus maskelli
or
Leptocybe invasa
), which can cause significant damage in young plantations and nurseries.
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The increasingly mild winters and the absence of predation are favorable to the long-term establishment of these insects.
In the event of an infestation, prune and burn the affected leaves or twigs.
Sheet produced by Lise-Margot Dumargne, Deputy Head of Culture at the Versailles-Chèvreloup Arboretum, National Museum of Natural History in Paris.