The following lists of species that
will thrive in specific situations are not all-inclusive. They are
intended only as a general guide to help determine what species of euc
will do best in your garden. They are recommendations for species
that will do well in that situation based on their range of adaptability.
Selecting a euc
for your site
SITE refers to the specific
place in which the tree is to go. It includes factors that directly
affect the immediate environment of the tree. Such factors would
include soil quality, the amount of available sunlight in the site, and
other aesthetic and utilitarian considerations regarding the tree's intended
use in the landscape.
Sunny vs. shady sites: As a general
rule, eucs are sun-lovers. In maritime climates they will tolerate
any amount of sun, and most despise shade. In hot, low-latitude climates,
many of the species which thrive under cooler conditions will tolerate
a little more shade. No species will grow in deep shade. The
two most shade tolerant hardy eucs are E. crenulata and E. neglecta.
E. regnans, E. obliqua, E. fastigiata, and some related species are
also a little more shade tolerant than most.
Wind exposed sites: This is generally
easy to figure out by assessing what species grow in exposed alpine sites
in habitat, and which grow in forests. Forest-dwelling species tend
to be the taller ones and are not suitable for wind-exposed areas.
Some good species for generally exposed sites would include E. apiculata,
E. approximans, E. coccifera, E. cosmophylla, E. dendromorpha, E. elaeophloia,
E. glaucescens, E. gregsoniana, E. gunnii ssp. archeri, E. kitsoniana,
E. kybeanensis, E. lacrimans, E. mitchelliana, E. moorei, E. parvula, E.
pauciflora and its subspecies, E. perriniana, E. rubida, E. rupicola,
E. saxitilis, E. scoparia, E. spectatrix, E. stricta, E. triflora, E. urnigera,
E. vernicosa and E. willisii.
Sites with salty air: Generally,
species that have thicker leaves such as the snow gums (E. pauciflora
and its subspecies) have proven tolerant of these conditions, as well as
globulus and E. cosmophylla. Some other good prospects
might include E. cordata, E. brookeriana,E. willisii, E. nitida,
and other coastal and Tasmanian species. There are probably a lot
of other species that would also be suitable so I would encourage experimentation
in this area.
Dry soils: There are a large
number of drought tolerant eucs, though some species require moist soil.
Of the tender species from northern and western Australia, there is an
especially high proportion of drought tolerant eucs. This is why
they are so successful when planted in Mediterranean areas. Some
of the species covered on this page that I would recommend for drier
sites would include E. acaciiformis, E. aggregata, E. amygdalina, E.
apiculata, E. approximans, E. badjensis, E. barberi, E. blaxlandii, E.
camphora, E. cinerea, E. cosmophylla, E. dalrympleana, E. deuaensis, E.
dives, E. glaucescens, E. goniocalyx, E. gregsoniana, E. gunnii and
its subspecies, E. lacrimans, E. leucoxylon, E. mannifera and its
subspecies, E. melliodora, E. nicholii, E. nitida, E. nova-anglica,
E. ovata, E. paliformis, E. pauciflora and its subspecies, E. polyanthemos,
E. pulchella, E. radiata, E. rodwayi, E. rubida, E. scoparia, E. smithii,
E. tenuiramis, and E. youmanii.
Waterlogged soils: Many eucs
will grow on soils that are either seasonally or permanently waterlogged.
Such species include E. aggregata, E. barberi, E. brookeriana, E. cadens,
E. camaldulensis, E. camphora, E. cephalocarpa, E. cinerea, E. consideniana,
E. cordata, E. cosmophylla, E. crenulata, E. gunnii and its subspecies,
johnstonii, E. kitsoniana, E. macarthurii, E. microtheca, E. moorei, E.
morrisbyi, E. neglecta, E. nova-anglica, E. ovata, E. parvula, E. rodwayi,
E. stellulata, E. strzeckelii, E. subcrenulata, E. vernicosa, and E.
yarraensis. Generally any species referred to as a "swamp gum"
will tolerate waterlogging. No euc can be guaranteed to grow in seasonally
flooded areas, but E. camphora ssp. camphora, E. neglecta
and perhaps a couple others might be worth trying in these extreme conditions.
Poor soils: With a few exceptions,
all eucs generally tolerate poor soils. If your soil is poor you
can probably grow just about any euc if you mulch it. Some of the
blue gums and other species which require cooler, moist climates are a
little less tolerant of poor soil.
Rich soils: Some species do not
thrive on rich organic soils such as those found on valley floors.
They require gritty soil with less organic matter to perform well.
Any species called "ash" or "mallee ash", and a few other alpine mallees
might be difficult to grow in rich heavy soils.
Clay vs. sand: Most species grow
fine on clay, but some of the ashes and other rare species such as E.
olsenii are difficult to grow on clay since they require a more gritty
soil similar to the alpine situations where they are native. All
species grow fine on sandy soils, but if it is a very dry climate, they
may not survive without a lot of irrigation. Sandy soils lose moisture
very quickly, so if the tree is likely to dry up because of the climate,
than any species that is not drought tolerant will require irrigation throughout
the tree's life.
Soils with high pH:E. cordata,
E. dalrympleana, E. macarthurii and E. parvula have all been
shown to do fine on soils of high pH. It seems that many additional
species will also grow on high pH soils, becoming chlorotic after planting
out but recovering once they are well established. There is much
research yet to be done in this area.
Utilitarian and aesthetic considerations:
Eucs for small spaces: The following
species will truly not outgrow their listed height of 15 - 20' or so: E.
apiculata, E. gregsoniana, E. kybeanensis, E. obtusiflora, E. stricta,
and E. vernicosa. (Many eucs often get much larger than expected
because the heights cited for them are too conservative.)
Eucs for screening purposes:
Any euc species with a prominent lignotuber can be grown as an annually
coppiced screen, always making very dense regrowth after being cut back.
They can also be sheared, although it must be done frequently, and an occasional
hard cutting back helps to regenerate their growth. Species with
dense crowns that keep a lot of their lower branches can also be used as
very large scale screens. The most reliable for this purpose are
E. crenulata, E. stellulata and E. subcrenulata.
Eucs for feature ornamentals: Most
eucs make grand specimen trees in landscapes and parks. Some species
with the most beautiful combination of foliage, bark and form include E.
coccifera, E. cordata, E. crenulata, E. dalrympleana, E. glaucescens, E.
kybeanensis, E. mannifera and its subspecies, E. mitchelliana, E.
morrisbyi, E. nitens, E. pauciflora and its subspecies, E. perriniana,
E. rossii, E. rubida, E. rupicola, E. saxitilis, E. scoparia, E. subcrenulata,
E. tenuiramis, E. triflora, E. urnigera, and E. viminalis.
a euc for your climate
CLIMATE refers to the overall
climatic patterns of the region where the tree will grow. Within
any given climate is a wide range of sites. It is important to know
what species will be adapted to your climate or else it might not do well
regardless of how suitable the site is.
Temperate climates vary somewhat
in conditions such as timing and duration of freezes, summer temperatures
and humidity, and rainfall amounts and patterns. I have divided up
these climates on a regional basis. This is not really intended to
be a complete guide, but just a general guide of what eucs have been able
to grow in certain climates and which ones might be promising based on
The Pacific Northwest and
are two places that have reasonably similar climates to one another and
where people have tried to grow eucs for a long time. The climate
is generally maritime but with warmer summers than immediate coastal fog
belts. Some have argued that Britain's climate does not experience
as severe freezes as the Pacific Northwest because the cold air is moderated
when it crosses the North Sea. There is probably something to this,
but I would say that, except for Britain's much milder coastal microclimates,
the two regions are still reasonably comparable to each other. E.
aggregata, E. coccifera, E. glaucescens, E. gunnii, E. neglecta, E. parvula,
E. pauciflora ssp. debeuzevillei, E. pauciflora ssp. niphophila,
E. perriniana, E. rodwayi, E. saxitilis, E. subcrenulata, E. urnigera,
and E. vernicosa are all generally well adapted in this climate,
but obtaining a hardy provenance can make or break the success of a euc
tree in the Pacific Northwest or Britain.
Mediterranean climates are generally
able to grow a wide range of eucs as long as it is not too cold.
Places such as Southern California, western South Africa and of course
the Mediterranean are very much to the liking of most eucs. Some
of the more popular species of eucs in such regions include E. viminalis,
E. globulus, E. camaldulensis, E. blakelyi, E. cinerea, E. bridgesiana,
E. mannifera and its subspecies, as well as E. sideroxylon, E. leucoxylon,
E. stricklandii and many other showy-flowered species. There
are also many fantastic species from northern and western Australia such
as E. papuana, E. citriodora, E. diversicolor, E. macrocarpa, and
E. salmonophloia that are popular landscape trees in Mediterranean
climates. Many of these species are not particularly hardy and fall
outside the scope of this page.
Very cold areas such as in USDA
zones 5-6 (and colder) cannot really grow eucs reliably to a large size.
Generally, you have two options if you live in such an area and wish to
grow a euc permanently in the ground (as opposed to a potted plant that
can be brought indoors for the worst cold). You can choose one of
the hardiest species and find a sheltered microclimate for it, plant it
in the spring and hope it makes it through a few winters - for which the
best species might be E. gunnii, E. neglecta, E. lacrimans, E. parvula,
E. pauciflora ssp. niphophila, and E. pauciflora ssp.
debeuzevillei - or you could grow them in a perrenial border or
some such thing, and plan on the tree dying back to the ground annually
and regrowing in the spring. Should you choose the latter method,
any hardy species that forms a strong lignotuber (such as E. cinerea,
E. nova-anglica and E. elliptica) will do. For more information
Discussion of Eucalyptus Cold-hardiness.
Mild coastal climates throughout
the world are generally able to grow a wide range of eucs. These
climates are characterized by a lot of rain and fog, and very few extremes
of temperature. This includes such places as sheltered coastal areas
of the British Isles, the wet north coast of Spain, the immediate coast
of southern Oregon and California (and sheltered points north of there),
most of New Zealand (especially Fiordland), western Tasmania, and coastal
Chile around Valdivia. (A reasonably similar climate is found at
many areas of very high elevation and low latitude - for example, E.
globulus thrives at 10,000' in Ecuador.) Although many species
will grow in such places, some of the best ones adapted to these extreme
maritime climates include E. brookeriana, E. coccifera, E. cordata,
E. cypellocarpa, E. dalrympleana, E. delegatensis, E. dunnii, E. fraxinoides,
E. globulus and its subspecies, E. kitsoniana, E. mitchelliana,
E. morrisbyi, E. nitens, E. nitida, E. obliqua, E. olsenii, E. paliformis,
E. regnans, E. sieberi, E. triflora, E. urnigera, and most of the really
hardy alpine species. (See also "Sites with salty air" above.)
The Southeast USA and Texas (referring
especially to USDA zones 7 - 8) have very hot summers and mild winters
with occasional hard freezes. It is difficult to say what species
will ultimately prove successful in this region, since it is too cold in
winter for most of the heat-loving tropical and desert species, and too
hot in summer for many of the hardy alpine species. I would suggest
that some of the best species for this region include E. aggregata,
E. alaticaulis, E. camphora, E. cinerea, E. goniocalyx, E. mannifera
and its subspecies, E. neglecta, E. nicholii, E. nortonii, E. nova-anglica,
E. rodwayi, and E. stellulata; and possibly also E. bridgesiana,
E. cephalocarpa, E. dives, E. morrisbyi, and E. tenuiramis. There
have also been local reports of some success with E. pauciflora
ssp. niphophila in Alabama and Texas, and E. parvula and
E. gunnii in Alabama. Milder areas (zone 8b - 9) should do
well with E. blakelyi, E. camaldulensis, E. microtheca, E. nandewarica,
and E. polyanthemos. Much more testing of eucs in the Southeast
is needed. (Milder areas of the Eastern Seaboard - eastern
North Carolina, Virginia, etc. - might try some of the species recommended
for the Southeast and for the Pacific Northwest, since the climate is not
quite so hot as the Southeast.)
The New Zealand Southland, and
some other locales in the Southern Hemisphere such as central Tasmania
and parts of Argentina, have a climate generally favorable to most hardy
eucs, but presenting a unique set of challenges. The climate is mostly
maritime in that there is plenty of rainfall and a general absence of extremes,
but takes on some characteristics of a continental climate, including the
interesting phenomenon of summer frosts. Graham and Heather Milligan
in the New Zealand Southland have conducted extensive trials and have found
the following species to be among the best for such a climate (though many
more will do reasonably well): E. camphora, E. crenulata, E. glaucescens,
E. gunnii, E. gunnii ssp. archeri, E. perriniana, E. parvula, E.
rodwayi, and E. stellulata.
The Gulf Coast and Florida will
probably not be able to grow many of the species covered on this page.
Most of the alpine species do not tolerate subtropical heat and steamy
weather through most of the year. Many of the Mediterranean species,
as well as some of the hardier rainforest species, might eventually prove
True desert climates will not
be able to grow most of the species listed here, but do have a wide range
of species to choose from. There is a huge variety of species from
hot interior areas of Australia, most of which tend to be hardy to about
15 - 20°F.
True tropical climates will not
be able to grow the species covered on this page either. Although
there are many tropical euc species, the hardy ones do not generally survive
more than a couple years in climates with year-round heat.