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Guide to Growing Eucalyptus

Myrtaceae family

The family Myrtaceae contains the genera Angophora, Corymbia, & Eucalyptus.

The latest published documents has listed 789 known species in 1996, with an additional 123 subspecies or varieties.   Further species are still to be named with a known current total of 912.

There is a move to further divide the Eucalyptus into seven different genera:  Blakella, Corymbia, Eudesmia, Gaubaea, Idiogenes, Monocalyptus and Symphyomyrtus.

Only 5 species occur exclusively outside Australia, they are Eucalyptus deglupta, E. urophylla, E. orophila, E. wetarensis and Corymbia papuana.

The differences between Angophora - Corymbia - Eucalyptus:

Angophora: Currently contains 12 species, all are native to Eastern Australia, they do not have an operculum (bud cap), the flowers are always white and the leaves are always opposite.

Corymbia: Contains 113 species, made up of bloodwoods and ghost gums.

Eucalyptus: All others. Flowers are predominantly white or cream in color, however, other colors are pink, yellow, red, purple or orange.  Adult leaves are usually different than juvenile leaves and are mildly to densely aromatic.

EXPECT THINGS TO CHANGE !

Propagation: We propagate all of our Eucalyptus by seedLimited research on cuttings, root division, etc. has been done throughout the world, the main focus is still on seed germination. Some seed must experience a cold dormancy period before germination will take place, this is commonly known as "stratification."  Other seeds may be planted as soon as the seed is obtained.  New techniques are being tested using "Smoke Water" with good results.  "Smoke Water" is basically obtained by piping smoke from burning native vegetation through water.  Chemicals found in the "smoke" are released/dissolved in the water.  The Smoke Water is then poured over the seed and media.  We have also improved our germination rates with some species using other seed enhancing substances like Potassium nitrate or Gibberellic acid, but the average person can just plant the seeds and still generally have good germination.

Providence: The best Eucalyptus seed to work with for cold hardy species comes from high elevations in cold areas.  It goes to reason the cold hardy seeds come from the coldest places and tropical varieties from warm places.  Tropical plants do not over-winter outdoors in our Virginia climate, but our cold hardy plants can do fairly well in tropical zones.

Types of Eucalyptus: Broken down into seven categories:

1.    Mallee: Low growing types with a number of stems rising from what is known as a lignotuber.  This is a modified root system and enables the plant to produce new shoots even after it has been destroyed above ground (generally by fire or cold).  If a cold winter knocks back your Eucalyptus, it can usually be cut back to the lignotuber and the plant will re-sprout and grow again.  Eucalyptus Cinerea, although only rated hardy to about 14 degrees, has survived actual temperatures of minus 20 degrees at our Louisa Virginia nursery.  The plant was cut back to the ground in early spring and still had 14 feet of new growth within two years. Not all Eucalyptus have lignotubers.
Some of the mallee types are: Angophora hispida, Eucalyptus Anceps, E. Approximans, E. Burdettiana,  E. Macrocarpa and others.  Mallees tend to come from arid to semi-arid areas, although they can be found in the colder areas as well.

2.    Gums: Shed a layer of bark from most or all of the trunk and branches.  It leaves a smooth, usually light colored trunk. Some examples are Eucalyptus Aggregata, E. Archeri, E. Bridgesiana, E. Cinerea, E. Neglecta.

3.    Stringybarks: The bark is made up of long, string-like fibers.  The bark is also usually gray to reddish brown.  The tree trunks are normally long and straight and make good timber. Example: Eucalyptus youmanii.

4.    Peppermints: These species have a fine, interlaced bark.  The bark may be fibrous, but the fibers are very fine and crumble when rubbed.  The leaves have the characteristic peppermint odor when crushed. Examples are Eucalyptus coccifera, E. dives, E. nitida, E. pulchella, E. radiata, E. tenuiramis.

5.    Boxes: Have flaky, scale-like bark over the trunk and all branches.  The leaves and buds tend to be smaller than on other Eucalypts, the wood is generally close grained, durable and excellent timber quality. Examples are Eucalyptus lansdowneana and E. polyanthemos.

6.    Ironbarks: Have a hard, deeply ridged bark. Examples in this group include Eucalyptus leucoxylon, E. melliodora and E. sideroxylon.

7.    Yates: Are usually smaller in habit with very large gumnuts.  The flowers are produced in what is known as a gumnut, the seed is carried inside this nut and takes about 2 years to mature.  E. lehmannii has very large gumnuts.

Hybrids: Many of the Eucalypt species will cross-pollinate and form new speciesWe often see new species in the daylily family as an example.  The Eucalyptus seed we receive from Australia usually breeds true, yet, there are times when there are distinct differences in plants from the same seed lot. 

Eucalyptus Culture:
Generally speaking, all Eucalypt species require full sun with an average soil.  There are two species that grow naturally as an understory of other trees, Eucalyptus crenulata and E. neglecta.  Both of these species will grow well in semi-shade. (I have found Eucalyptus archerii, camphora and gunnii have done well in semi-shade also.)

Fertilizing: One word sums it up - DON'TWhen it comes to fertilizers, one key thing to remember is that most all Australia plants do not like phosphorus.  In fact, phosphorus toxicity is a real challenge in growing some Australia plants.  Phosphorus is the middle number of the N-P-K ratings found on fertilizers.  We have found that most of the Australia plants we grow receive sufficient phosphorus from the soil and no additional fertilizers are needed.   I am going to make a distinction here, we grow in a "soilless" media that contains no earth or dirt.  Our nursery media is primarily bark, peat, perlite and vermiculite.  As such, it contains no nutrients.  Generally we add fertilizer into our growing media for balanced plant growth.  When you plant out your specimen into the landscape, you do not need to add any fertilizers. 

Most Eucalyptus species do well in average drained soil, although some species will tolerate more moisture such as Eucalyptus aggregata E. rodwayi, E. camphora, E. crenulata, or E. gunnii species.  These occur naturally on un-drained sites that are frequently waterlogged.  Australia soils, for the most part, are very shallow and well drained being either a sandy soil over sandstone or granite.  A well drained soil would be much preferred over clay.

Planting your Eucalyptus:
It is generally recommended to plant your Eucalyptus as soon as possible.  Water before and after planting.  Ideal is to get the plant into the ground and established well before winter sets in.  Avoid damaging the root system as they do not like root disturbance.  Some in the industry say you should not transplant any Eucalyptus over 18 inches tall although I have not had any problems when I utilize the air root pruning method of the RootMaker products. Normal growing methods of using round, plastic pots for growing Eucalyptus can lead to girdling of the root system if left in the pot too long.  I have various products I use in production of liners including "bottomless" pots, RootMaker pots and other methods.

Prepare the planting area:
Simply dig a hole, not much larger than the rootball.  Do not incorporate peat or other soil improvements. This can cause a barrier to water movement and will exaggerate drought in the summer on light soils or cause water-logging in heavy soils during the winterIf your soil is poorly drained, consider not planting quite as deep.  There is no need to break the soil or roots up on Eucalyptus species and they generally resent this!  It is recommended the top of the media level be planted level or above the surrounding soil surface.  If you feel you must plant deeper, go no more than 1-2" below the soil surface.  Firm the soil and water.  Apply a top dressing of decorative stone like marble chips or perhaps lava rock. I do not recommend using bark mulches as a top dressing.  Bark does tend to hold down weed growth, however the down side is that it also retains moisture which can rot off the root system.

Staking:
Another key factor in growing Eucalyptus species is staking.  It is strongly recommended you do not stake unless absolutely necessary!  If you feel you must stake to correct a leaning problem, do not leave plant stakes on the tree longer than the first growing yearPlants do sometimes need extra help to get them to grow straight the first year.  Not all species need to be staked, the mallee types certainly do not need it and some species are going to be crooked because that's the normal growth pattern.  If you feel you need to stake it, I recommend the stake be no longer than 1/3 of the total height and remember to remove it by the beginning of the second year.
 I have found the most appropriate stake to use is schedule 40 pvc plastic pipe.  You can usually get a 10' section at your home improvements store for about $1.  I use 1/2" pipe, but will probably start switching to a larger size like 1" or perhaps 1 1/2".  I found I can use the larger pipe size as a plant stake and water reservoir as well. The larger the pipe, the larger the reservoir you have to get you through drought periods.  You can cut the pipe at a 45 degree pointed angle and push it into the soil as it is somewhat rigid.  I still occasionally water the soil, but it appears easier to just fill up the pipe and the water is wicked through the soil to the root system.  This puts the water where it is actually needed!  Trees I plant in the landscape are rarely near a garden hose, so this method works for me.  I also use a plastic surveyors tape to tie the trees.  It is soft, flexible, comes in different colors and is easy to work with.  As a bonus, if you use a different color each year, then it is easy to see which plants need to be "de-staked" as the season progresses.  Again, it's just simple things that seem to work. 

Providing Winter Protection:
In our trip to Australia in 1999, I saw many unique ways to provide protection to young plants until they get established in the landscape.  These are simple, inexpensive ways to enhance your plants' survival chances.  There are several ways to accomplish this, but all rely on the same principle - to reduce the wind desiccation of young plants during the winter months.  Basically, you drive three stakes into the ground, forming a triangle around the outside of the plant.  Then, obtain some clear or white plastic garbage bags, cut the bottom off to make a sleeve.  Pull the sleeve down over the stakes which will provide wind protection to the plant during the winter.  The cover remains open at the top to prevent heat buildups on sunny days.  You can also place some pine tags around the base of the plant inside the cover for added insulation.  I like pine tags as they don't absorb water like leaves would do and they don't mat down like leaves. See picture 2 below.

Of course, not everyone will need to go to these extremes for winter protection, just us folks trying to grow Eucalyptus species in very cold climates.

Picture 1 below shows several different ways to provide protection: Plastic bags, (we also tested short sections of large diameter pvc pipe we had on hand.)
 

  Plastic bag/pipe test                   Winter protection using plastic bag

WHY GROW EUCALYPTUS ?

Fragrant oils:
Most all Eucalyptus contain fragrant oils.  Most of us are aware of that "Eucalyptus smell", but there are other scents as well.  Some are apple, honey, or lemon scented varieties.  Eucalyptus foliage runs from the very fragrant to those that are only mildly fragrant.

Aromatherapy is quite popular these days.  Although it may be cheaper to buy a bottle of Eucalyptus oil, the pleasure of "home grown" can be much more rewarding. 

Preserving Eucalyptus: If you want to preserve fresh foliage, use a 50-50 glycerin and water mix.  Stick the cut ends of stems in this mixture in a low light area, in about 2-3 weeks, the Eucalyptus will have absorbed the glycerin and be ready for use.  Glycerin can usually be obtained from a pharmacy and you can easily do your own preserving.  Much of the Eucalyptus I have seen in the craft stores all smells alike and has been obviously dyed in different colors.  To each his own, but why waste the beauty of the many varied "natural" scents of Eucalyptus?  You certainly won't find any naturally lemon scented Eucalyptus at your craft store!  Talk about fragrance, the lemon scented Corymbia citriodora has got to be tops!

Flowers:
Most Eucalyptus species have flowers that are cream color and not of any particular interest.  However, there are a few varieties grown mainly for their beautiful colored flowers.

Red to Pink Flowering Types:
E. Caesia ssp caesia, E. erythrocorys, E. erythronema, C. ficifolia, E. forrestiana, E. leucoxylon rosea, E. macrocarpa, E. nutans , E. tetraptera and E. torquata.

Purple: Only one species, E. lansdowneana var albopurpurea

Yellow: E. campaspe, E. dolichorhyncha, E. erythrocorys, E. leucoxylon, E. orbifolia, E. pachyphylla, E. pimpiniana, E. presissiana, E. stoatei, E. woodwardii, E. youngiana.

Foliage:
Most, but not all, Eucalyptus species have two different types of foliage, sometimes at the same time.  The juvenile foliage is usually what most people prefer and this can easily be obtained by pruning back the tree.  Mature foliage is usually sickle shaped while juvenile foliage can be very different.  Eucalyptus perriniana, also called spinning gum, is unique because the stem grows right through the leaves.  When it is dried, the leaves detach and spin on the limb, hence the name spinning gum.  Foliage colors can range from green to many different shades of silvery blue and can be lightly to heavily scented.  It can also be very small to very large in size.  (As a side note, if you want to give yourself a really special treat, take about a dozen fresh leaves from your Eucalyptus and add them in with your bath water.  If you are a shower person, then you can put the leaves in a nylon mesh bag and attach it to the shower head with a rubber band.  Most any Eucalyptus species will work, but I found the Corymbia citriodora (lemon scented gum) to be one of the best!)   Please refer to Glossary for detailed information on foliage (leaf) shapes.

Koala food:
No, we don't have any Koalas at our nursery, but we do get several request each year about what to feed them.  Koalas are picky eaters and they prefer only a few types of leaves as their main diet.  When their main habitat is destroyed, they have been known to browse other tree species.  The preferred species are:
E. camaldulensis, E. globulus, E. goniocalyx, E. ovata, E. punctata, E. tereticornis Other species include: E. propinqua, E. elata, E. viminalis, E. dalrympleana.

Sugar Gliders:  We ARE NOT Sugar Glider breeders, nor do I consider myself as a professional when it comes to their habits or nutritional needs.  Please do not ask me to tell you what to feed your sugar glider!  I am not experienced in the nutritional needs for sugar gliders.  You can view this link  gliders  to see what "others" say about sugar gliders. 

Parakeets, budgies, parrots, snakes, stick insects, lions, tigers and bears oh my!.....  Don't even ask!                                                                                                                                                                                                                                                     

Bark:
Many of the Eucalyptus species have interesting bark, it may be smooth, flaky or stringy and there are a few with multi-colors such as the Eucalyptus rubida or candlebark gum.  This link has 25 color pictures of bark.  The bark can be an outstanding feature of many Eucalyptus.
 

Size and growth rates:
Most of the larger Eucalyptus species are extremely fast growing.  Once established in the ground, many grow at a rate of 6 to 10 feet per year.  Other varieties may only grow 2-3 inches per year.

Sizes in Eucalyptus range from about 3 for the  E. Kruseana or Brookleaf Mallee to others that are well over 200 feet tall.  Actually, the tallest hardwood tree in the world is a Eucalyptus species, Eucalyptus regnans.  Documented records indicate this tree grew to a height of 480 before the wind broke it off !  It is even taller than our giant sequoias out in the western part of the USA.

Cold Tolerant Species:
See Eucalyptus_Zones.htm  

USDA Climate Zones: These links provide information to help you determine your local climate zone: http://www.usna.usda.gov/Hardzone/ushzmap.html         

Eucalyptus as house plants:
There are many species that will do well as house plants as long as proper culture conditions are met.  We generally use the more tropical varieties as house plants here in our Zone 6 winters.  However, since I have to pay to heat the greenhouses, I might as well use them to extend our growing season.  My favorite is the Corymbia citriodora for it's lemon scent.

Use a large pot and place it in a south facing window area with bright light with moderate water over the winter.

Some of the most popular species for house plants: Corymbia citriodora, ficifolia, Eucalyptus Baby Blue, bridgesiana, cinerea, glaucescens, gunnii, nicholii, parvula, urnigera.  (Occasional pruning is needed)

Eucalyptus growing in tubs or containers:
Many species can be grown in outdoor planters provided they are at least 2 in diameter and winter protection is provided.  It is important to remember that most Eucalyptus species grow fast.  Pruning is required so the top growth does not get out of balance with the root system.
The best suggested species for this system are: Eucalyptus archeri, coccifera, crenulata, kybeanensis, nicholii, parvifolia, pulverulenta and vernicosa.

Pruning methods:
Coppicing Necessary if you require the juvenile foliage for cut foliage, or to keep a tall species small.
For juvenile foliage: cut back to about 18 inches from the ground with a slightly sloping cut facing south (to prevent water standing on the stump).  Remove all side shoots.  After about a month, the dormant buds break all the way up the stump and young shoots can be seen by six weeks.  These shoots develop vigorously during the summer months because the root system has already been established, providing you with the fresh, juvenile foliage.

To restore a leggy or leaning tree: Cut the tree back to 4 to 5 inches above ground.   Make a smooth, slightly sloping cut to the south to facilitate water run-off.  The coppice shoots develop from the dormant buds in the live bark or from the lignotuber buds.  Many shoots develop, but they gradually thin themselves out.  Finally two or three remain, select the best one to develop as your tree.

Pollarding: Can be done to trees from 3 to 6 years old.  This is commonly done on the faster growing Eucalypts to lower crown height and encourage branching at the top of the tree.  The faster growing species will tend to make a single trunk, shed their lower branches and the crown advances up the tree.  Cut off the main trunk between 6 and 10 feet above ground.  Do not remove any of the side branches.  The crown will develop rapidly and one branch will gain dominance and will be your new main central leader.

Specimen tree: If you want a specimen tree with a single trunk for the first 6 feet, do not prune away any of the lower branches until the tree has had two seasons growth.  You can remove any lower branches after that.  No pruning is necessary for the faster growing species because they will shed their lower branches naturally.

Hedging: Species suitable for hedging include Eucalyptus archeri, coccifera, parvifolia and subcrenulata.  It is essential to prune the plants at the end of the second seasons growth to begin to shape them for a hedge.  Remove 1/3 of the height and cut to an inverted "V" or pyramid shape around June.  By hedging at this time, the naked buds are able to develop before the end of the growing season so that new growth starts immediately in spring.
The following year, remove 1/4 to 1/3 of the height again in the same inverted "V" shape.  Once the hedge has reached the required height you desire you can cut it back every year in the same manner.  The purpose of the inverted "V" is that you prevent the upper leaves from shading out the lower leaves and it will discourage the plant from shedding its lower branches.  

If all else fails, go to this link: Consultation and Research

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Last modified: 08/28/11
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