Eucalyptus camaldulensis (River Red Gum) Growing Guide

What is Eucalyptus camaldulensis?

Eucalyptus camaldulensis is Australia’s most common Eucalyptus tree, growing across numerous inland river ranges. Growing up to 30m tall in a relatively short time, it is a great tree for families establishing larger gardens and landscapes, with a 20m wide evergreen canopy.

As a perpetually flowering tree, it is useful for various pollinators, but especially native bees, to which it offers a reliable nectar source all year round. 

The hermaphroditic flowers have both male and female parts, meaning they can be pollinated by both wind and insects, which does mean they readily self-seed (potentially problematic in drier parts of the country where their foliage and timber create a fire risk).

Natural Habitat of River Red Gum Eucalyptus 

Eucalyptus camaldulensis is semi-drought tolerant, but grows naturally in areas with transient water sources – there’s a clue in the common name: river red gum. Thankfully it’s not reliant on these conditions, but it does mean it tolerates fairly boggy conditions provided the moisture isn’t stagnant.

Pond or lakeside sites are ideal, especially in mixed plantations, offer the closest situation to its natural habitat, but it will grow just fine in open spaces.

Identifying Eucalyptus camaldulensis

The bark of Eucalyptus camaldulensis is smooth and evenly cream-coloured. Mature trees have patches of pinks and browns along the bark. Its foliage is long and willowy, with a metallic blue hue, and the flowers are typically creamy-white, growing in clusters, and they provide a striking contrast against the foliage.

Common Uses for River Red Gum

As can be expected of one of Australia’s most common native trees, its wood has had many common uses through the ages. Most notably, Eucalyptus camaldulensis is a vital building material for homes as well as smaller household items in aboriginal communities.

In more modern history, it was a popular timber for the construction of railways, bridges and fencing. In both cases, its pest-repelling properties make it a useful termite-resistant timber.

The seeds of red river gum eucalyptus are also a brilliant bush tucker, raw and cooked, and the white scale that occasionally coats its leaves is an unusual but delicious snack (just scrape it and roll it up into a lolly). 

Even today, river red gum’s most popular uses are medicinal. The resin, mixed with water, is an antiseptic lotion, while burnt bark can be ground up with fats or oils to treat burns, or mixed with water to relieve diarrhoea.

Edible Uses

The edible seed pods are small pointed, acorn-like forms, attached at the intersection of a leaf and young stem. The flowers, which are also edible, and have a gorgeous honey flavour, are frothy white globes with pale yellow centres.

How to Grow Eucalyptus camaldulensis

Despite its natural river-side habitat, river red gum really isn’t picky about its situation in our gardens but, like all trees, a little care and attention for the first two years after planting will go a long way towards creating a healthy happy tree in the long run.

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Ideal Conditions for Growing Eucalyptus camaldulensis

In short, this Eucalyptus species will grow nearly anywhere you put it, but it's still worth understanding the variations in soil types, moisture and light levels these hardy trees prefer.

Soil & Drainage

There are very few rules for soil types, as Eucalyptus camaldulensis will grow on acid, alkaline or neutral soils, and can tolerate rich, poor and even saline soil types.

In terms of soil structure, you can plant directly into sandy, loamy or even heavy clay soils, where these trees will tolerate drought and heavy rainfall equally well.

Light & Temperature

Red river gum eucalyptus is a tall tree, so will eventually head for the light, but young trees can be planted in part shade to begin with. Once established, this Eucalyptus species is hardy through cold winters and dry summers, so is suitable to all parts of Australia.

Shelter

No shelter is required for these trees, which can grow in highly exposed conditions. However, as with any young tree, it does benefit from loose staking for the first couple of years to protect it against any extreme winds while its roots establish and its trunk builds strength.

Planting Eucalyptus camaldulensis

When planting a young river red gum, follow the standard rules for tree planting. Dig a hole twice the width of the root ball, and loosen the soil at the base of the hole. Position the tree at its best angle before backfilling the hole and firming it in with your heel. 

Add a supportive timber tree stake at a 45-degree angle, pointed into the prevailing wind, and use a looped tree tie so it can have about 10cm of movement (rocking slightly in the wind is useful for young trees).

How to Propagate Eucalyptus camaldulensis

Propagating Eucalyptus camaldulensis is pretty simple. Seeds will germinate without any special care, and cuttings are unreliable so it's best to avoid the technique altogether.

Propagating from Seeds

While you can find river red gums seeds for sale, it's usually more effective to start with fresh seeds harvested in late spring or early summer. Flowers are followed reliably by seed capsules, 5-8mm across, which can be sown directly, or stored in a cool dry place until you are ready to sow.

Sowing at this time gives optimum germination conditions, and the longer days are ideal for the young plants in mid to late summer as they develop young leaves. 

Sow river red gum seeds on the surface of a free-draining sandy compost (any standard seed compost will do), and water them until the soil is moist but not soaked. Leave them in a sunny spot outdoors or on a ventilated windowsill.

Germination should take between 3-5 weeks, and plants can be pricked out into larger containers when the roots fill their pots.

How to Care for River Red Gum

Like all Eucalyptus trees, river red gum can be treated in a wide variety of ways, and after the first couple of years, can generally be left to its own devices. Below are a few basic things to get to know about pruning and feeding Eucalyptus camaldulensis, with an emphasis on caring for young Eucalyptus trees, or coppiced plants.

Pruning Eucalyptus camaldulensis

Red river gum eucalyptus does not require pruning and will grow into an elegant and exceptionally tall tree if given the chance. However, that needn’t be a worry for smaller gardens as it can be readily coppiced, and even pruned into a loose hedge.

Whenever you do cut Eucalyptus camaldulensis, use clean loppers or a sharp tree saw to make the cleanest cuts possible, as breaks and tears in the branches can become infected. 

The benefit of coppicing river red gum is that it will keep the plant down to about 2m tall at most. You can coppice alternately, or cut the entire plant back harshly each year, which adds to its attraction as an alternative to willow, which can be treated in the same way.

Feeding Eucalyptus camaldulensis

Eucalyptus camaldulensis does not require regular feeding, but mulching in the spring of its first two years (immediately after planting, and again the following spring) will help to conserve moisture at its base, and reduce the risk of frost damage or drought while roots establish.

If you notice rare signs of nutrient deficiency (yellowing, anaemic foliage) then an application of garden compost or leaf mould as a mulch will hopefully improve its appearance. Slow-release fertiliser granules can be slightly faster acting too.

Do note though, that these nutrient deficiencies are often caused by root disease, and it is rare to find a case where river red gum can’t find the nutrients it needs from the soil. 

Harvesting & Storing River Red Gum

As an attractive edible bush tucker tree, Eucalyptus camaldulensis will usually have something worth harvesting all year round, but there are times when its flowers are at their best, and its seeds are at their most abundant.

Much of what we know about the edible uses for these plants is passed down through generations, and not particularly well researched, but it is generally seen as a safe plant to use in foods, infusions, or as a snack in its own right.

Knowing When River Red Gum is Ready to Harvest

The flowers of red river gum eucalyptus can be used in several ways, from sweet fritters to sweeteners in hot teas and cold water. The sweet flavour is present at all times of year, but I find it is strongest in spring, and followed well by a readily available supply of seeds, that can be dried and stored in airtight jars for several months.

It’s important to note that river red gum seeds are edible, but that many Eucalyptus seeds are not, so do check and check again before consuming the seeds from river red gum.

How to Store Eucalyptus camaldulensis

The flowers of Eucalyptus camaldulensis don’t store well in themselves but can be infused into water and cooked down into a concentrate that will freeze easily. A weaker infusion will freeze and add a gentle aromatic sweetness to cocktails through summer.

The seeds are easy to prepare. Simply let them dry out and then use them as an astringent spice – aboriginal uses include a porridge made of the ground seeds too, but I couldn’t comment on the culinary success of that.

The scale, scraped from the leaves, isn’t technically part of the tree - it’s an insect that lives on the leaves of the river red gum. Bizarrely, it tastes sweet, and when found in large enough numbers can be scraped off in sheets.

Common Eucalyptus camaldulensis Pests and Diseases

Ironically, the scale that is potentially a useful bush tucker is also a pest and it's one of the few pests that these insect-repelling trees do attract. Aside from scale, there are several caterpillars that develop and pupate on Eucalyptus trees, as well as Eucalyptus gall wasp and Eucalyptus sucker. 

Below, we’ll look at each in detail with guidance on how to deal with them, as well as whether or not they pose a threat, rather than simply being part of the ecosystem. 

Eucalyptus camaldulensis Pests

Eucalyptus gall wasp

Eucalyptus gall wasps can cause galls (swells) on eucalyptus leaves. Their grubs live within the gall until they are ready to emerge, and in large enough numbers will cause excessive leaf-drop that can harm the health of the tree. 

The best way to deal with these pests is to encourage predators, like spiders and birds into your garden, but if you notice galls on leaves, remove them, burn them and keep on top of the process for that season. In time, the numbers will reduce.

Eucalyptus suckers

Psyllids, commonly called suckers, are a group of sap-sucking tree bugs, with countless species across the globe. The common black psyllids found on river red gum are not usually problematic and should be left alone. Not only do they do little harm to the overall health of the tree, but they are a useful food source for many birds.

If an infestation becomes overwhelming, they can be scraped off by hand, or sprayed with a  strong jet of water to manage the problem.

Caterpillars

The emperor gum moth is the best-known eucalyptus caterpillar, but there are several other species to look out for. Keep in mind that these caterpillars have limited habitats, and on mature trees, should be left alone.

If you find these spiked caterpillars on young river red gum trees, they should be removed and fed to the birds, as they can be destructive while plants are young and don’t have as many leaves to spare.

Scale

Scale is not generally a problem on mature Eucalyptus plants, but can cause discolouration across foliage, with yellow or grey patches developing on the surface of the leaves when they have fed from underneath.

This can be treated with organic fungicides, or simply removed where necessary.

Eucalyptus camaldulensis Diseases

Unlike most Eucalyptus species, river red gum isn’t overly susceptible to root fungus issues, and overwatering is quite an extreme occurrence. Fungal problems can be caused by feeding pests, and spread by wind to damaged foliage, or torn branches.

The major diseases for Eucalyptus camaldulensis are crown rot and canker. 

Cankers are distinct growths – tumours – on the stems and trunks of trees, and in some cases can be cut out, but in most cases either need to be lived with, or removed entirely. In most cases, this will require removing the affected limb of the tree, with the aim of reducing spread.

Crown rot, also called collar rot, is when damaged material becomes infected. This can spread back to the root, and affect nutrient and water uptake to the rest of the plant. Some causes can be treated, and others will lead to the necessary removal of the tree.

River Red Gum Frequently Asked Questions

Is Eucalyptus camaldulensis an evergreen?

Eucalyptus camaldulensis is a gorgeous evergreen tree, with willow foliage that is held all year round. As well as having evergreen foliage, it will continue flowering all year round in ideal conditions.

Is river red gum toxic?

River red gum leaves are toxic in large quantities, but the oil extracted from the tree is often used in low doses in oral and topical medicines with no adverse effects. The flowers are edible, and the seeds have various edible uses too.

How do you identify Eucalyptus camaldulensis?

E. camaldulensis is fairly simple to distinguish from other Eucalyptus trees thanks to its long willowy foliage and smooth creamy bark. The flowers are creamy-white with pale yellow centres. If you are unsure of the species, avoid eating the seeds as some eucalyptus seeds are toxic.

What diseases do Eucalyptus camaldulensis get?

E. camaldulensis is generally disease-tolerant but can be affected by various fungal problems and leaf diseases, as well as cankers, and some blights.

How tall does Eucalyptus camaldulensis get?

E. camaldulensis grows to about 30m tall, but coppiced plants can be kept to 2-3m tall, or even shorter with regular pruning. Multi-stemmed plants vary in height but will still reach in excess of 20m for a wonderfully ornamental tree.

What are the disadvantages of river red gum?

One disadvantage of river red gum is that it can be quite brittle while young, so it does need staking as a young tree for at least two years. Once established the branches are sturdy and flexible enough to cope with high winds.

Is river red gum a good firewood?

River red gum is an excellent firewood, with a long burning time. It grows quickly too, so small branches can be used as kindling, and mature logs are relatively affordable compared to many other common firewoods.

Where did Eucalyptus camaldulensis get its name?

The name ‘camaldulensis’ of E. camaldulensis (river red gum), comes from the Italian monastery of Camaldoli near Naples. The common name is a far reach from its native range of Australia and was in fact given to a single specimen grown in the monastery, which has stuck ever since.

What are the medicinal uses of Eucalyptus camaldulensis?

E. camaldulensis has been used for centuries in various medicinal capacities. Some of the most common include antiseptic rubs and oils, but it is also anti-inflammatory, antipyretic and a useful medicine for relieving diarrhoea. 

Why is my Eucalyptus tree suddenly dying?

The most common cause of sudden onset problems with any Eucalyptus tree is crown rot, caused by a fungus which will rot the tree from the inside out. In some cases, if the problem is isolated to one limb, it can be removed before it spreads.

Can you propagate Eucalyptus camaldulensis from cuttings?

You cannot reliably propagate E. camaldulensis from cuttings, so it is always preferable to grow them from seed. However, while it isn’t easy, it is possible. If you would like to try growing river red gum from cuttings, you will need a rooting hormone gel, a shady spot, and a well-drained growing medium for the best chance of success.

Is river red gum easy to split?

As well as being a great firewood with a long burning time, river red gum is easy to split, and makes easy work of preparing fuel for burning as a result.

Is red gum a hardwood or a softwood?

Red gum is a hardwood suitable for carpentry and building, with a dark red heartwood and paler outer material. It makes a beautiful ornamental wood and has great durability.

For more inspiration, check out our round-up of types of Eucalyptus to grow in Australia.