Silver Dollar Tree (Eucalyptus cinerea)

A small to moderately sized tree with a compact, dense crown of beautiful silvery foliage. Eucalyptus cinerea is one of the most popular eucalypts in cultivation today, especially in temperate regions and colder areas. Good choice for privacy planting and screening.

I. Appearance and Characteristics 

Eucalyptus cinerea, commonly known as the Argyle apple, mealy stringbark or silver dollar tree, is a species of small- to medium-sized tree that is endemic to south-eastern Australia.

Eucalyptus cinerea is a tree that typically grows to a height of 15–30 m (49–98 ft) tall and forms a lignotuber. It has thick, fibrous, reddish brown to grey brown, longitudinally fissured bark on the trunk to the small branches. 

The leaves on young plants and on coppice regrowth are arranged in opposite pairs, sessile, glaucous, broadly egg-shaped to more or less round, up to 80 mm (3.1 in) long and 50 mm (2.0 in) wide. Intermediate leaves are arranged in opposite pairs, glaucous, egg-shaped to lance-shaped, 48–90 mm (1.9–3.5 in) long and 20–45 mm (0.79–1.77 in) wide on a petiole 4–15 mm (0.16–0.59 in) long. Adult leaves are arranged alternately, lance-shaped, 90–140 mm (3.5 – 5.5 in) long and 15–50 mm (0.59 – 1.97 in) wide on a petiole up to 11 mm (0.43 in) long. 

The flower buds are arranged in groups of three in leaf axils on a peduncle 2–9 mm (0.079 – 0.354 in) long, the individual buds sessile or on a pedicel up to 3 mm (0.12 in) long. Mature buds are glaucous, diamond-shaped, 6–8 mm (0.24–0.31 in) long and 3–5 mm (0.12–0.20 in) wide with a conical operculum. Flowering occurs between May and November and the flowers are white. 

The fruit is a woody, conical to bell-shaped capsule 4–7 mm (0.16 – 0.28 in) long and 5–9 mm (0.20 – 0.35 in) wide with the valves level with the rim or slightly beyond.

Argyle apple is typically found from north of Bathurst (33° S), in central west New South Wales, to the Beechworth area of Victoria (36° S). It is often part of grassy or sclerophyll woodland communities growing in shallow and relatively infertile soils, usually as part of the understorey. Subspecies cinerea occurs in the Australian Capital Territory and Captains Flat in New South Wales and subspecies triplex in the Australian Capital Territory and Captains Flat in New South Wales. Subspecies victoriensis is only known from hilly country near Beechworth in Victoria.

II. How to Grow and Care

Sunlight

Eucalyptus likes a lot of light, so settle your plant somewhere in your landscape that receives at least six hours of direct sunlight daily. Likewise, eucalyptus plants grown indoors should be kept near a bright window, preferably one that faces south.

Temperature and Humidity

Eucalyptus prefers warm temperatures between roughly 65 and 75 degrees Fahrenheit, and it likes a moderate humidity level. It cannot survive prolonged exposure to temperatures below 50 degrees Fahrenheit. So if you’re growing your plant in a container, bring it indoors when you expect chilly temperatures.

Watering

Eucalyptus is somewhat drought-tolerant once it’s established. However, it really doesn’t like to be left dry for long periods, and doing so might cause it to drop leaves. A good rule of thumb is to water when you can stick your finger into the soil and feel dryness at your fingertip. This often will amount to watering weekly if you haven’t had rainfall, especially for container plants.

Soil

Eucalyptus can tolerate most soil types, but it needs soil with good drainage. For container plants, use a well-draining potting mix. A slightly acidic to neutral soil pH is best.

Fertilizing

If you’re growing your plant in the ground, it typically won’t need fertilizer. However, container plants will deplete their nutrients more quickly. So fertilize them with a low-nitrogen houseplant fertilizer throughout the growing season, following label instructions.

Pruning

Eucalyptus trees generally don’t need much pruning. However, you can prune overgrown, broken, or misshapen branches to keep the plant looking attractive. The best time to do so is in the summer, but avoid pruning during very humid weather.

Propagation

Cuttings

Eucalyptus trees are most commonly grown from purchased seeds or nursery plants. Home garden trees don’t often flower and produce their own seeds. They also can be propagated via cuttings, though this isn’t always successful. But this is an inexpensive and convenient way to get a new plant, especially because eucalyptus can be hard to come by at garden centers. The best time to take cuttings is when a tree is between 2 and 12 months old; rooting mature stems is difficult. Aim to take your cuttings in the late summer. Here’s how to grow eucalyptus from cuttings:

• Prepare a small pot of 3 parts composted tree bark to 1 part perlite. Add a slow-release fertilizer, following label instructions for the size of the pot. Moisten the growing medium.
• Use sterile pruning sheers to cut a stem that’s around 5 inches long with four to eight leaves. Cut just above a leaf node.
• Remove the leaves on the lower half of the cutting. 
• Dip the cut end in a rooting hormone, and then plant it in the growing medium almost up to where the leaves are. 
• Keep the container in bright, indirect light in a room that’s around 70 degrees Fahrenheit. Make sure the soil remains slightly moist.
• Roots should form in about a month. At that point, you can move the new plant to a sunnier spot and gradually space out waterings. Once the weather is warm enough, bring it outdoors for progressively longer stretches before planting it in the garden.

Seed

When considering how to grow eucalyptus from seed, note that the seeds first must be chilled in the refrigerator for two months before planting. Sow them in the late winter indoors roughly 10 to 12 weeks before your area’s last projected frost date. Use a seed-starting mix in peat pots that you’ll eventually be able to plant right into the soil to avoid disturbing the roots.

Sow seeds on top of the growing medium, only lightly covering them. Place the pots in a warm spot with indirect bright light, and keep the growing medium moist but never soggy by misting it. Seeds should germinate in two to three weeks. Once the seedlings are about 6 inches tall, they’re ready to go outdoors.

Potting and Repotting 

Eucalyptus plants are often grown in containers outside of their hardiness zones. Growing eucalyptus in pots allows gardeners to protect their plants from the cold by bringing them indoors. However, many gardeners treat container eucalyptus plants as annuals, starting with new plants each year because of their rapid growth rate. This allows them to remain manageable as houseplants and on balconies and decks.

These plants don’t like their roots to be disturbed. So it’s best to start with a large container to avoid having to repot. A 5-gallon container is a good size. And while unglazed clay is an ideal material to allow excess moisture to evaporate through its walls, you might want a plastic container that’s lighter to move around. Just make sure any container has ample drainage holes, and use a quality fast-draining potting mix. 

Overwintering

If you’re growing a container eucalyptus plant outside of its hardiness zones, you must bring it indoors to survive the winter. Do not let your plant be exposed to frost, which can damage or kill the foliage. Place it near your brightest window, preferably a southern-facing one, for the winter. Do not fertilize the plant, and slightly back off on watering.

Pests and Diseases

Common Pests

Eucalyptus plants are fairly free of any major pest or disease issues. But you might occasionally spot eucalyptus long-horned borers, especially on stressed plants. Holes in the bark, oozing sap, and foliage discoloration are signs of an infestation. Remove the infested area of the plant immediately, as insecticides are not effective against borers.

Common Problems 

Eucalyptus trees remain relatively healthy when in their preferred environment. However, in suboptimal conditions, they can come down with certain issues.

Leaves Turning Brown

Leaves turning brown on a eucalyptus tree can be a sign of too little moisture. That’s likely the issue if you notice leaves curling up or dropping as well. In that case, up your watering to keep the soil lightly moist but not soggy. Brown leaves also can be a sign of disease, especially fungal diseases. If just a small area is affected, remove that portion promptly. Or treat with an appropriate fungicide.

III. Uses and Benefits 

Eucalyptus cinerea is an excellent specimen tree for the wider landscape, and for the medium garden.

Good choice of species for xerophytic gardens, Australasian planting schemes and desert garden landscapes – very tolerant of dry soils once established.  Your tree will require watering for its first two summers after planting to ensure it becomes established.

Floral Art: Excellent cut foliage. One of the most popular species grown in the USA, and it should be more widely grown in the UK.

Ecology:  flowers are useful to bees and other pollinating insects. The shredded foliage of this species is excellent at keeping Chicken nest boxes and hen houses free of red mites, which detest the presence of Eucalyptol. I used to line our Chicken boxes with shredded leaves, strew the floor and pile up the spindly branches for the chickens to make nests.

Environmental: Tolerant of arid environments, poor stony dry soils once established. It is essential that your Euc.is given lots of water during its establishment phase before you abandon it to its fate.  The tree needs to establish a good root system before it can survive in these challenging conditions.