Caring For Your Eucalyptus After Planting

Once correctly planted, Eucalyptus are relatively easy to look after. A word of warning, they do shed bark and even though they are evergreen, leaves only last a year or so and then they drop in favour of new leaves being produced. This discarded vegetation makes excellent mulch and does not have to be cleared if it drops on to your borders, unless it is smothering smaller plants.

Apart from that, you just need to keep an eye on a few simple things until your new tree is growing away; most importantly watering and weed control.

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1. Watering:

• It is very important to keep an eye on this. Whilst you don’t want the Eucalyptus to become dependent on your watering it every week, you certainly do not want to let a young Eucalyptus wilt. Wilted Eucs turn brown and crispy – only Mary Berry will be impressed!  All evergreens (i.e. shrubs, conifers and trees) are unable to make a good recovery if they are allowed to wilt badly. Deciduous plants have the safety net of being able to drop their leaves and very often revive when water becomes available again.

• So water your tree well, if it needs it and especially in a drought or if wilting occurs. This could mean watering once a day on sandy soils to watering once a week. Administer 1-2 gallons of water to your new tree during a prolonged dry spell. In any event, be vigilant over watering until your new tree is established and has grown several feet, which means that its roots are establishing well into the surrounding soil.

• Full details on specifically how much water to give your new tree will be supplied with your tree, when it is sent to you.

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2. Feeding:

We recommend that you seek out a plant food that is going to encourage sturdy growth and help ripen wood in the autumn, in preparation for winter.

The fertiliser needs to be low in phosphate, but high potassium and also contain trace elements, which are vital for balanced growth. A minuscule amount of nitrogen is fine, but excessive nitrogen is to be avoided at all costs: it encourages shoot growth at the expense of root growth.  Avoid products such as ‘Gromore’.  Nitrogen also produces soft sappy growth, which is susceptible to frost damage.

Recommended Plant Feed:

• For trees planted in the ground, take a look at our Eucalyptus Smart Fertiliser on the Growing Accessories Page. It is the perfect balance of NPK for Eucalyptus plus a little Magnesium to help keep them in good condition.  It contains little bit of Nitrogen, next to nothing in Phosphorus and a generous amount of Potassium to help produce healthy growth and ripen wood for winter.

• Chempak No. 4 High Potassium Soluble fertiliser; for flowering plants, but is good for Eucalyptus too!  Excellent plant food for Eucs growing in terrace pots and planters.  This can be fed to plants in the ground, but may be rather hard work, and you would be better off with granular food – see above

What the elements of a fertiliser do for the plant:

• Nitrogen (as Ammonia and Nitrates):  encourages fleshy shoots and leaves which is great for lettuce, but disastrous for Eucalyptus. It exacerbates the shoot to root ratio, encouraging instability.  It can also increase frost sensitivity. Eucalyptus only require small quantities of nitrogen and only during the growing season.

• Phosphorus (present as phosphates): this element makes for sturdy beefy growth. Whilst it does not alter root to shoot ratio, it does significantly increase tree girth, root weight and encourages trunk growth.  Avoid fast-food forms of phosphate like Miracle-Gro.  Antipodean plants find it difficult to tolerate large quantities of phosphorus and it can seriously set them back.

• Potassium (aka Potash): this mineral is involved with the movement of water, nutrients and carbohydrates in the plant tissues. It has many functions, two of the most important (from our point of view) are:  (i) the efficiency of water use and  (ii) how Eucalyptus tolerate and overcome stress brought on by drought, excessively high and low temperatures (winter hardiness) and resistance to pests and diseases.   Good potash levels in August will lead to improved winter hardiness, by helping the tree ripen its wood, in readiness for the onset of winter.  Being highly soluble, Potassium leaches out from sandy/stony soils very quickly. Clay soils are more stable and are not likely to be deficient in this important mineral, if their general fertility levels have been maintained.

• Sulphur is vitally important for fast growing Eucalyptus.  It is one of the building blocks for amino-acids, used to manufacture proteins.  This highly soluble element is required by the tree to support its fast growth and due to the ‘clean air act’, it’s a bit thin on the ground these days.  If coppicing for biomass or pollarding for cut foliage production, you will need to top up levels of sulphur after a harvest.  Secondly sulphur helps to acidify the soil (something else which Eucalypts appreciate).  This in turn makes iron available to the Eucalyptus and iron reacts with phosphorus, reducing its availability.  However, sulphur should only be applied sparingly. Over doing an application can seriously through your soil chemistry ‘out of whack’!  Always follow manufacturer’s recommendations.  Plant nutrition is all really clever stuff 

• Trace elements: Molybdenum, Manganese, Calcium, Iron, Magnesium etc. These act in a similar way for the plant as vitamin tablets do for humans and are important for balanced growth. (This next bit does appear elsewhere on our website, but it is important and cannot be over-stressed).

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3. Competition from surrounding vegetation:

• 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.

• This is why it is immensely important to keep the area underneath your tree absolutely free from weed 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.  A ‘Eucalyptus Lawn’ is a lovely garden feature to walk through.

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Mulching:

Keep a 600-1200 mm (2-4 feet) diameter circle around the base of your new tree free of lawn/grass and weeds for at least 2 years, to ensure maximum establishment. Mulch either with a biodegradable mulch mat or our preference is for 150 mm (6 inches) depth of bark chips, for at least 2 years.

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Benefits of mulching:

• Reduces moisture loss, particularly in the summer months.

• Keeps nutrients available for longer.

• Acts as a winter root-duvet, protecting the roots and helps to keep the soil from freezing.

• Can help prevent weed encroachment.

• Avoid using compost, manure or anything that composts down quickly, producing nitrogen, as this will not only encourage weeds to grow around the base of the tree, but also result in excessive Eucalyptus top growth.

Herbicides for weed control:

Take care not to get spray drift of herbicides (especially a Glyphosate based herbicide) on to young trees or bark of older trees – it can be fatal.

4. Grazing and stock protection:

• Cattle, horses, deer, sheep and goats love to stand under the cooling shade of mature Eucalyptus.  The copious amount of water given off by the leafy canopy creates a welcome haven on a hot sunny day and the Eucalyptol helps deter flies.  However, it is not recommended that you plant Eucalyptus in a way that livestock can reach to eat the leaves, stems or bark. Whilst the species grown in this country are not as toxic as the sugar gum E. cladocalyx, Eucalyptus generally are full of oils and complex compounds and should be treated with caution and respect, particularly around ruminants. In any case, a young euc savaged by a cow is simply not going to survive anyway!

• When planting the odd Eucalyptus in a livestock field, protect with 4 strong posts and pig-wire or rabbit wire to prevent access to the young plant

• If creating a biomass plantation, exclude all livestock and protect young trees from deer, if they are a local problem

• Rabbits and hares will eat most Eucalyptus so protect young trees either with a soft mesh rabbit guard or with top grade rabbit wire compounds secured in place on timber stakes a good 450 mm radius away from the new tree. E. glaucescens  and to a degree E. subcrenulata have some track record of being unpalatable, but other species are likely to be nibbled. We have found that once a rabbit (or deer) has torn a strip of bark up the length of the Eucalyptus trunk, it does not recover and very often dies.

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5. Plastic tree shelters

• Plastic tree shelters are not recommended, unless they have a lot of ventilation holes. Eucalyptus do not become fully dormant; they will grow when the temperature is high enough; usually around +5 Celsius. In spring and autumn, the temperature can fluctuate wildly inside a tree shelter, meaning that on warm days the tree will grow, but young developing shoots will be damaged when there are frosty nights.

• In addition, tree shelters can be very humid, leading to disease problems (such as Botrytis mould), unless they are the type that have lots of holes drilled in them.

• We have found that the typical plastic spiral rabbit guard can saw a young Eucalyptus in half on a windy day

• Use rabbit-wire guards to deter deer from munching your tree and soft plastic mesh rabbit guards for discouraging hares and rabbits.

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6. Pests and Diseases to look out for:

In their native Australia, there is a whole host of leaf-munching, stem-boring pests and invading fungal diseases all looking forward to making Eucalyptus trees their next meal.

However, generally speaking, Eucalyptus tend not to suffer from many bugs or pathogens in the U.K. Inside a greenhouse, conservatory or polythene tunnel you may get the odd investigative greenfly, but that soon disappears after the first few mouthfuls of Eucalyptus juice. Powdery Mildew can coat the leaves of one or two species (E. neglecta tends to get this a bit indoors), but this too dissipates once the tree is planted outdoors.   Botrytis can invade a Eucalyptus that is overwintering in a humid greenhouse with poor ventilation, but is easily remedied.

The chances of your Eucalyptus contracting something nasty are quite slim, but here are a few to look out for if you are at all worried about the health of your trees:

• Silver Leaf Fungus:  This disease is the most common Plum tree killer, but silver leaf fungus (Chondrostereum purpureum) will also invade other fruit trees (Apple, Peach), Hawthorn, Laburnum, Poplar, Rose, Portuguese Laurel and Eucalyptus.   If your Eucalyptus are growing in an area where the silver leaf fungus is prevalent and you are carrying out a serious amount of pruning on your trees, it is advisable to do the work when there are a few dry days and paint the wounds with a compound such as Arbrex Seal and Heal, to prevent the fungal spores entering the pruning wounds. Sterilise your pruning equipment using a horticultural or household disinfectant, before and after use.

• N.B. False Silver Leaf is caused by stress induced by drought, malnutrition, sudden unseasonably hot or cold weather or pest attack. It does not result in branch dieback. An improved cultural regime of feeding, mulching and watering will help the plant recover.

• Other fungal and bacterial nasties:  Whilst not a susceptible as other shrub and tree species, Eucalyptus can contract the usual tree diseases of Honey Fungus and Phyophthora especially if grown on ground that is poorly drained.    Bacterial canker can invade a damaged stem and cause havoc, as with any woody plant.

• Blue gum Psyllids (Ctenarytaina eucalypti):  More annoying than terminal, these pesky sap-suckers are visible on the new growing tips; cosmetically damaging for young foliage, they are not an issue on mature trees.  Present in the UK since at least 1922, this sap sucker lives entirely on several (but not all) species of Eucalyptus. Snow gums E. pauciflora group are generally not attacked by psyllids.

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Young nymphs and adult psyllids attack the juicy new growths of shoots and leaves (a bit like greenfly). They tend not to be interested in the tough mature foliage. As a consequence, young trees and those being coppiced for foliage production tend to be most at risk of attack.

What to look out for:  Feeding on the nutritious wax on the new growing points, the bugs create a frothy, woolly looking mass out of the Eucalyptus cuticle. Then for protection, the psyllids encase themselves in a carapace of shed skin and honeydew (delightful!).  Treatment is worth carrying out using a proprietary systemic insecticide on non-flowering specimens. Spray your young tree at the first signs of attack and again 4 weeks later.  This should keep your tree clean for around 3 months in the growing season. They are not active over the winter months unless in a warm environment like a conservatory.  If you are organic, we suggest you look at using a spray formulation containing either a chili or garlic preparation.  The use of household detergents is to be actively discouraged as it will strip the waxy cuticle off your Eucalyptus foliage, causing serious damage.

Biological control:  because both Eucalyptus and psyllid are not native to the UK, the bugs don’t seem to have any natural predators.   Back in the 1980’s, trials were carried out using the imported parasitic wasp Psyllaephagus pilosus on cut foliage plantations.  This tiny black wasp preys exclusively on the psyllids, so does not affect any British wildlife.  Now it is naturalised in the UK and can often be found in and around Eucalyptus plantations.  We certainly have a small population of them living at the nursery.

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7. Moving a Eucalyptus Tree and how to do it (if you really need to)

Our first piece of advice is ‘Don’t do it’! Eucalyptus have exceptionally sensitive root systems and if damaged, they go into a monumental sulk. If the tree is in the wrong place, for whatever reason, you could try moving it provided it has only been growing there for no more than one year.  After two growing seasons, it will not transplant successfully; there will be far too much root disturbance. Far better to chop it down and start again with a new specimen planted in the correct place.

Therefore, from the very beginning, it is far better to choose your Eucalyptus species carefully, matching it to your requirements and growing environment.