When choosing your species, it is important to consider the mature height of the species, deciding at the outset whether you will prune to control growth (a bit like choosing to prune an apple tree to keep it smaller), to coppice or pollard as a management system or to grow as a hedge or screen with annual trimming.
We often get asked why Eucalyptus grow so fast – Eucalyptus are perfectly adapted to compete and survive in their natural environment of Australia, New Zealand and Tasmania. They have evolved to germinate quickly under the right conditions and then to grow into a tree as rapidly as possible before Koala, Kangaroos and insects nibble them to death. In their natural habitat, Eucalyptus are plagued by leaf and bud munching bugs and fungi which continually check and reduce their growth. Grasses and other vegetation increase the competition for food, water and light and poor, infertile stony soils make for generally hostile growing conditions. As a species, they are genetically geared towards a ‘quick getaway’, to put as much distance between them and the local competition as possible.
When grown in cultivation in Britain, Eucalyptus do not experience the same challenges as the Australian bush (just a whole set of new ones!). Generally, garden soils are richer and more fertile. There is less competition from other vegetation, pests or diseases and attacks from itinerant Koalas are virtually non existent.
Free from indigenous nibbling pests and fungi, Eucalyptus in this country will grow much faster than your average garden tree. Despite the windy, cooler climate and erratic weather, you can expect the larger species to achieve 2-3 metres of new growth each year, provided your new tree is vigorous, not root-bound and planted in a relatively sheltered location. There are a few notable species that will not achieve this rapid growth rate:
E. vernicosa is very small and slow growing.
The Snow gum family (E. pauciflora and its subspecies) initially grow quite slowly in their first few years, whilst establishing a root system; growing much faster in year three and beyond.
There is an interesting correlation between rate of growth of a Eucalyptus species and its potential mature height. We have experienced this in the nursery. Trees that grow rapidly tend to grow into tall trees and correspondingly, slower growing species tend to produce smaller trees.
It cannot be expected for a Eucalyptus to rocket up to around 16 feet over a period of 3-4 years and then stop growing: it doesn’t work like that with Eucalypts, any more than it does for Leyland Cypress, Thuja or Sycamore trees.
Chart showing expected growth rate and approximate height in maturity of Eucalyptus (to be used in reference with the specific variety listing). Rate of growth above is an estimate which will be reached under optimum conditions in years 2+ after planting and establishment.
Factors which reduce the UK growth rates shown above:
Growing in a location with a short growing season (Scotland), with reduced heat and light availability.
Growing in a windy, exposed location.
Local competition from grass/lawn and close proximity to other trees and shrubs.
Dry soils especially in areas of erratic or low rainfall.
Poor infertile soils.
Aroma of the leaves: the smell and sound of the foliage are a pleasant sensory addition to any garden
Winter interest: bark detail and foliage
Leaf colour: both new growth and winter foliage
Flowers: the majority of hardy Eucalyptus flowers are white/creamy white, they tend to be prolific and rich in nectar favoured by bees and other pollinators, which is a ‘good thing.’
Armed with your ‘design brief’ you can now tackle the list of species with confidence and match a tree with your wish list.
Still unsure? Send us an email and we will try and help you reach a decision.
Eucalyptus do not have periods of dormancy. Eucalyptus are evergreens and unlike deciduous trees, they do not take a winter break. Further they do not produce a dormant terminal bud (think of Horse-chestnuts with their large sticky buds), nor do they shut down like Pine trees. Quite simply, if there is sufficient water and the temperature is above +5 °C; we find that in the nursery, they will continue to push out new shoots. Therefore, Eucalypts grow for longer periods during the year and have greater annual extension growth than your average garden tree.
Eucalyptus motto: ‘Life is for living, why waste time sleeping?’
Over winter 2011/12, the E. urnigera in our nursery grew, on average, over 300 mm in two months in an unheated polythene tunnel (with temperatures of between -4 °C and +10 °C) and with barely moist compost.
Further, during periods of drought, they will stop growing and wait patiently; they don’t pause or become dormant like a Philadelphus or Fuchsia. The minute rainfall arrives, Eucalyptus just start right back into growth again.
About 90% of a Eucalyptus tree’s roots grow in the top 300 – 400 mm of soil, which makes perfect sense when you consider where they come from: a challenging environment, where the ability to be the first to access limited rainfall is vital for survival. Eucalyptus are very efficient at taking up water from the soil.
It is therefore immensely important to keep the area underneath your tree absolutely free from weeds and grass (lawn) competition for a minimum of two years after planting; to ensure maximum successful establishment of the young tree.
Grassing down around Eucalyptus in later years can help towards restricting and slowing down growth, but should only be done once the tree is happily established and it has grown to at least 3 metres tall. If you have space a ‘Eucalyptus Lawn’ is a lovely garden feature to walk through, a collection of ornamental Eucalyptus set in nicely mown grass.
Some varieties of Eucalyptus respond well to regular coppicing (see species list). Not only does this immediately reduce the overall size of the plant, but the practice also restricts top and root growth, by temporarily removing the food factory of the plant. This, in turn, prevents the Eucalypt from storing up nutrients and building a bigger root system, so future extension growth and annual output is temporarily restricted.
Distance from buildings and structures needs to be considered: it is vitally important not to plant any tree too close to a building or important structure:
Firstly, to prevent the tree damaging the building
Secondly, to prevent the building restricting the establishment and growth of the tree
Eucalyptus in particular need access to direct light and an unrestricted sky, to be able to grow properly into a tree, so no overhead shade (except for E. neglecta and E. crenulata which will tolerate some partial shade).
Position your Eucalyptus at least two thirds its potential mature height away from a building on ordinary loamy garden soils and an even greater distance away from buildings if you have a clay soil (which has a tendency to shrink in periods of drought).
As a guide, if you choose a variety which could attain 10 metres in height you need to plant it approximately 6-7 metres away from any structure on loam and probably about 10 metres away, if you grow on clay.
Calculation: Mature Height x 0.6667 = Planting Distance from a building.
10 m tall x 0.6667 = 6.6m away from a building
Eucalyptus don’t have wildly aggressive root systems but their roots do grow very quickly and they are generally, shallow rooting; although this does depend on their growing conditions, soil type and rainfall.
The type of soil where your eucalyptus is to grow
Soil type should be considered, when selecting your varieties. For example: choosing a snow gum for a swampy garden is a really bad idea; it simply will not thrive. However, if you have what is termed ‘ordinary garden soil’ of a neutral to acid pH, you will be able to grow almost any Eucalyptus.
1. Acidic, Neutral or Alkaline – your soil pH and what it means to Eucalypts.
If you can successfully grow Camellia, Rhododendron and Azalea with healthy dark green leaves or blue flowering Hydrangeas, in your natural garden soil, it means you have an acidic soil.
Most Eucalyptus prefer mildly alkaline, neutral and acid soils (pH range 4.5 – 7.5), but that does not mean to say you have to worry too much about this issue. It has been found that when planting in a soils up to a pH of 8.5 (limey), the leaves of a great many Eucalypts may turn yellow upon planting, but recover their green leaves once established. It is generally acknowledged that more research needs to be done on this subject.
The following species will grow happily without fuss, in alkaline conditions, such as a shallow dry chalky soil or a limestone soil:
E. cordata, E. dalrympleana, E. macarthurii, E. nitens and E. parvula
2. Poor soils versus Rich Fertile soils.
Nearly all Eucalyptus will grow in poor stony soils, which are devoid of organic matter and are of low fertility. E. gunnii and its associates, (along with other blue gums that prefer cool moist conditions), may be a bit ‘sniffy’, but give them a good thick mulch and they should establish well.
On the other hand, there are some Eucalypts that will not thrive on rich heavy fertile soils, with a high organic matter content. As a guide, those species with the common name of ‘Ash’ or ‘Mallee Ash’, along with the Alpine gums may struggle under these organic rich conditions, because they are used to more stony poorer soils.
3. Clay soils versus Dry and Sandy soils.
Clay soils usually hold their fertility well and (outside periods of drought) have a good moisture content. At Hardy Eucalyptus, Grafton Nursery, we think red clay soils are easy to grow on (contrary to a general belief amongst the gardening public), as they are stable and can be improved with sharp sand and compost; although yellow and blue clays can be a bit challenging.
Most Eucalypts will grow quite happily on clay, even slow draining clays (but see our comments above about the ‘Ash’ and Alpine gums).
However, the following need to be assessed and taken into consideration:
It is a slow draining clay soil as opposed to seriously waterlogged?
Is the ground compacted, has it been trampled by livestock or horses (it may need subsoiling to relieve the compaction, if you are planting a large number of trees) ?
Assess the depth of the clay and the type of underlying subsoil or underlying rock.
How much organic matter is present?
Establish the presence of land drains
What is the height of the local water table?
How much rainfall is usually received during the year?
Sandy soils on the other hand are free draining and as a consequence tend to be hungry and dry. Again, most Eucalypts will be happy with these conditions provided there is sufficient rainfall throughout the year. Species that are listed as drought tolerant should be fine, but other Eucalyptus may well need to be supported with additional artificial irrigation to survive and thrive and they will benefit from a thick mulch too.
Eucalyptus that will thrive in drier conditions: (this list is not exclusive)
E. pauciflora and its subspecies of E. gregsoniana, debeuzevillei, lacrimans, niphophila
Generally speaking, even though they love water, Eucalyptus are not aquatic! A few Eucalyptus species will tolerate boggy ground, whilst many species will only put up with damp and temporarily squishy conditions, provided it drains for most of the year. It is all a question of degree and permanently water-logged soils are not ideal. Having said all that, any species that has ‘Swamp Gum’ as part of its common name will tolerate a higher degree of water-logging.
The following species are worth trying:
E. aggregata – would be our number one choice.
E. crenulata (another good one)
E. gunnii and its subspecies (a very tolerant group)
E. stellulata (but not in windy areas, because it may fall over)
E. aggregata E. crenulata E. gunnii and its subspecies can be found growing on the undrained peat moors of Tasmania and New Zealand, where surface water can linger for up to six months of the year. At a push, they will also grow (but in a stunted manner) in stagnant water sitting just below the soil surface, which even Salix and Populus will not tolerate. E. stellulata will also tolerate similar difficult, boggy conditions.
Drought Conditions: Eucalypts deservedly have the reputation of being able to withstand long periods without rainfall and are well adapted to survive the degree of drought we occasionally experience in the UK.
In their native Australia, New Zealand and Tasmania, the hardy Eucalyptus usually enjoy an annual minimum rainfall of 800 mm either evenly distributed through the year or as a winter maximum, but they can survive on less.
It is thought that their survival is attributable, in part, to the thick leathery nature of their leaves, which on mature trees of most species droop, reducing transpiration loss. However, young trees and newly planted trees will not tolerate drying out and drought conditions will be fatal for trees that are not well established. Keep an eye on your trees for the first summer and water well during periods of low rainfall.
As we have touched upon elsewhere on this website, Eucalyptus are sun-worshippers. Everything about them is adapted to cope with sunlight and the best quality trees are grown in bright light. Deep shade is the very thing guaranteed to make them miserable and pathetic. They become weak and spindly and will not grow into a decent tree. Shade cast by surrounding tall trees and shrubs and also from buildings will also force the young eucalyptus to grow tall and spindly.
As ever, there are a couple of exceptions. E. neglecta and E. crenulata are two varieties that will tolerate growing in a shady location. In their native environment they often grow as the understorey to larger trees.
Also some of the forest species will grow with a small amount of shadow. These are E. regnans, E. obliqua and possibly even E. delegatensis (it may be worth a trial).
Where ever possible, it is best to avoid planting in major frost pockets. Some of the alpine species will grow in this difficult micro-climate, but they tend to produce better specimens when grown in a warmer, more sheltered locale.
If a frost pocket is unavoidable, make your selection from the following species list:
E. archeri, E. coccifera, E. pauciflora debeuzevillei, E. kybeanensis, E. pauciflora niphophila, E. parvula, E. subcrenulata
Of all the elements, wind could be considered to be one of the most damaging to all trees, including Eucalyptus. On a small scale, leaves can be shredded causing desiccation. More violent wind breaks branches and damages the crown, even snapping the trunk off above ground level.
Prolonged windy weather causes both newly planted trees and top heavy trees with poor root establishment to sway excessively, loosening the soil around the root collar and tearing the roots.
In the worst case scenario, trees may be wind-thrown; the tree is up-ended, including the root plate and falls over. You only have to visit the forests of Scotland to see good examples of this, where conifers are planted on shallow soils over granite pavements.
If your newly planted Eucalyptus tree is thrashed around by the wind, you will see a cone-shaped hole appears around the base of the tree (socketing). This loss of soil around the root collar, combined with tearing of the roots, leads to establishment-failure, instability and even death. (I know that last section was a bit heavy, but it’s true).
In exposed environments with strong winds is it very important to get good root establishment for your Eucalyptus and ensuring it is well anchored into the surrounding soil. These problems can largely be overcome by planting smaller trees in preference for larger specimens and also staking the new tree; stake low down with a short sturdy stake. We also suggest that you implement a pruning regime for the first few years after planting, to aid development of a strong trunk and sturdy roots. See Planting is easy – staking and also Pruning for Windy and Exposed Conditions.
Make your selection from our list of wind tolerant species below and make the commitment to prune. This will not damage the appearance of your mature tree, but it could help it establish properly and survive.
Eucalyptus species which are native to the alpine regions (pauciflora group and E. kybeanensis in particular) are generally a good choice for windy, exposed sites in the UK. They are the sturdier types, with a good strong root system and also tend to be shorter growing.
Choose from the following for exposed and windy sites inland.
E. archeri (E. gunnii ssp. archeri)
and its subspecies of E. debeuzevillei, E. gregsoniana, E. lacrimans, E. niphophila
E. nitens and E urnigera are not noted for growing on exposed sites, but they survive in these locations by reacting to the wind in an interesting manner. The wind tears at their leaves and the trees will shed part of its crown, reducing resistance to the wind; a kind of self-pruning technique. They can look a bit tatty over the winter, but recover quickly with new growth in the spring and best of all, their roots remain firm.
Avoid the forest dwelling species for areas of high winds as they grow very tall and are best situated in a more sheltered aspect or amongst groups of other trees.
Coastal districts are subject to salt laden winds, which deposit sodium on to the plant leaves and this has a desiccating effect, secondary to that of the drying wind.
Select species which naturally grow in challenging areas and ones that have thicker cuticles to their leaves; such as:
And of course our alpine friends E. pauciflora and ssp. E debeuzevillei, E. gregsoniana, E.lacrimans, E. niphophila
If you garden near the coast and would like to grow other species of Eucalyptus than those mentioned above, we suggest you plant them in a sheltered position, protected from exposure. If the shelter is neither tall nor dense, it will be best to regularly coppice the trees to help them grow into decent specimens.
Growing on the East coast of the UK can be quite challenging. The easterly winds are particularly bitter during the winter, bringing in cold air from Siberia, so for this reason, we recommend growing only the very hardy species.
Generally speaking for trees grown in hostile exposed and windy locations, not just Eucalypts but all trees species:
They tend to produce a tree with a typically windswept appearance i.e. more growth on the leeward side and less on the windward side.
They will make substantially less annual growth than their counterpart grown in warm sheltered
locations and ultimately a much smaller tree.