Eucalyptus in the garden

E. niphophila, E. Debeuzevillei, E. archeri, E. gunni 'Divaricata', E. perriniana and E. neglecta are among the most hardy trees for a temperate climate. It's a mystery why these species aren't generally available in our climes. All you ever see are half-hardy forms of E. gunni on sale. The hardiness of a species is largely dependant upon where the seed uses has originated. There are places in Australia where extreme frost occurs regularly. Seedlings from trees there are much stronger than those from trees growing in milder circumstances. E. gunnii does not only occur in Tasmania; it also grows at 1200 meter (3600 feet) and tolerates considerable frost there. Seedlings from these trees have the best chance of success here. During very wet winters Eucalyptus are more prone to freezing (if the bark splits) than during normal winters. Fortunately, there are nurseries who pay special attention to the provenance of the seeds, and it is from these that 'de Groene Prins' offers young trees. De hardiness of seedlings is variable, though, so not every individual of a species is as hardy as the other. In any batch there will still be variation. The height at which a plant grows in nature is only partly determinant for it's hardiness. E. debeuzevillei is for example hardier than E. niphophila, yet it grows 400m (130 feet) lower down the mountainside. To summarize: E. debeuzevillei and E. niphophila are the hardiest species, which often survive even the severest of winters. The other species survive the average winter without problem.

Eucalyptus grows rapidly

Growth can be at most 2,5m (7,5 feet) per year! E. gunnii, nitens and perriniana are particularly quick growers. The tallest species here attain about 10m (30 feet). All of them can be pruned well. To get a strong tree, it is advisable to prune back even to a half the size - but only be this severe with E. archeri, E. gunni, E. gunni 'Divaricata', E. glaucescens, and E. perriniana. This has the advantage of making the trunk somewhat heavier in relation to the top of the tree. If you wish to harvest the green shoots, then you can prune the trunk in march at about 50cm (20") above the ground. The trunk should be at least 5cm (2") thick, so let the small ones grow a little first. (E. debeuzevillei, E. nitens, E. pauciflora en E.niphophila are less suited to this).

Where to grow your Eucalyptus

Full sun is necessary. Never plant under high trees! E. archeri, E. debeuzevillei and E. niphophila can tolerate a windy place well. The last two even tolerate sea wind. Choose a permanent place for your eucalyptus straight away, as replanting can turn out badly. Supporting your tree at about 30cm (12") against a low tree-stake is to be recommended. E. neglecta and E. Crenulatat tolerate light shadow.

Type of soil

It's not really necessary to improve your soil, so don't use any form of compost or enriched soil. Heavily fertilized trees can easily blow over. You can work a little organic fertiliser through really poor soil. It is important to keep the ground weed-free to 60cm (25") from the trunk. This is especially important in the first years to ensure optimal growth. Avoid weed-killers, Eucalyptus is extremely sensitive to these. The best weed-supressant is pine-bark shavings.

Eucalyptus suited to wet soil

	ï¿½F	absolute min temp in ï¿½C
aggregata	-3	+8 -19.5
camphora	+3	+14 -16.5
cinerea	+8	+16 -13.5
dalrympleana	+3	+12 -16.5
glaucescens	-2	+6 -19
gregsoniana	+3	+15 -16.5
gunnii	-5	+12 -21
rodwayi	-3	+6 -19.5
rubida	+3	+12 -16.5

These minimum temperatures relate to occasional, short cold-snaps and wind-free conditions! Extended periods of frost can be fatal. On chalky ground (pH > 7.5) the following species will grow: E. cordata, E. dalrympleana, E. marcarthuri, E. nitens and E. parvifolia. This last plant is the most hardy; the other ones will not survive every winter.

Flowering

All the species named here have white to creamy-white flowers. The ones with pretty red flowers are unfortunately not hardy here. The flowering period varies from species to species. E. debeuzevillei and E. niphophila usually flower from their 5th year. E. gunni and E. perriniana can bloom from their 4th year. E. archeri even flowers from it's 3rd year. Pruning inhibits flowering. Flower buds take a year to turn into flowers! You sometimes see flowers, buds and seed pods on the same branch.

Winter protection

When the trees are still small it's advisable to protect them in the winter with pine branches or reeds. Winter sun during frost periods can cause damage to the leaves. Also, the bark can split, which can lead to the plant dying. Sometimes the plants freeze off and new shoots will appear from the base of the tree. Don't forget that Eucalyptus, whilst not fully winter-hardy, show great adaptability! Selecting the hardiest seedlings and propagating further is a process which has only just begun. With luck you can have a magnificent garden tree within years. The trees in our jungle garden are living proof of this! In the following table you can see where each species comes from and how quickly it grows. Hardiness is indicted by the following words: Very good : application everywhere in NL and B is possible, even in unprotected areas. Good: the location should be moderately protected, severe winters could be fatal Reasonable: the location should be well protected by walls, thick conifers etc. Limited: situated only to coastal areas Weak: only survives mild winters The follwing list is limited; there are more species but these have not yet been sufficiently tested. In a protected town garden you can do much better than here in the open countryside!

Info per species

Species	Growth speed	Hardiness	Provenance
archeri	moderate	good	Tasmania1200 m
coccifera	moderate	limited	Tasmania 1100 m
debeuzevillei	moderate	very good	ACT. 1900 m
glaucescens	fast	good	N.S.W, 1700 m
gregsoniana	moderate	reasonable	N.S.W. 1300 m
gunnii	fast	limited	Tasmania 1200 m
gunnii 'Divaricata'	fast	good	Tasmania1150 m
mitchelliana	moderate	limited	Victoria 1700 m
neglecta	fast	good	N.S.W. 750 m
niphophila	moderate	very good	N.S.W. 2300 m
nitens	very fast	weak	N.S.W. 1400 m
parvifolia	moderate	good	N.S.W. 1100 m
perriniana	very fast	good	N.S.W. 1600 m
rubida	moderate	limited	N.S.W. 1200 m
vernicosa	slow	reasonable	Tasmania 1000 m

Eucalyptus repels insects!

Insects avoid Eucalytus; because of this they are being planted en masse to frighten away tics. We are also removing indigenous trees, as tics prefer oak, beech, etcetera.

Eucalyptus and global warming

Now extreme winters are possibly consigned to the past, the Eucalyptus can have a great future our climate! Nowadays many more species are being tested than in the past. Also, I test five plants of each species together, the idea being to progressively select the best and increase the chance of improving the plant. Maybe by selection and crossing on a larger scale we will work towards plants which develop well in our climate. In doing so, we can continue work on 35 years of field trials in Southern France. In the autumn of 2007 we planted a hedge of Eucalyptus Subcrenulata. In 2008 we will be planting: amygdalina, camphora, coccifera, glaucescens, goniocalyx, gundal (gunni x dairympleana), macarthuri, notonii, pulverulenta, rubida, urnigera en vernicosa.