The Silver Dollar Eucalyptus, scientifically known as Eucalyptus cinerea, is cultivated for its aromatic, silvery-blue, rounded foliage. This Australian native is a favorite in floral arrangements, where its distinctive leaves provide texture and a pleasing scent. While it can mature into a tall tree in its native habitat, it is often grown as a shrub or an annual in garden settings, especially for cut-flower production.
Essential Environmental Requirements
Silver Dollar Eucalyptus needs full sun, requiring a minimum of six hours of direct sunlight daily. Insufficient light results in a stretched, leggy plant with less vibrant, silvery foliage. If growing indoors, position it near a south-facing window.
The soil must be well-draining, as this plant is intolerant of standing water. A slightly acidic to neutral pH range is preferred for optimal health. When planting outdoors, amend heavy clay soil with organic matter like compost and coarse sand to improve drainage.
This species is hardy in USDA Zones 8 through 11, where it can be grown as a perennial shrub or tree. In cooler climates, it must be treated as an annual or grown in a container to be moved indoors during winter. Freezing temperatures can easily damage or kill the foliage and young growth, so frost protection is necessary.
Routine Watering and Feeding
Watering frequency changes as the Eucalyptus matures and establishes its root system. Young plants require consistent moisture and should be watered deeply and regularly for the first few months. Allow the top inch or two of soil to dry out slightly before watering thoroughly again.
Established, in-ground plants develop drought tolerance and require minimal supplemental watering. Container-grown plants need more frequent attention, often requiring weekly watering during warm, dry periods. Ensure the pot has drainage holes and the soil never remains soggy, as overwatering is a greater danger than underwatering.
Eucalyptus plants are adapted to poor soils and generally have low nutrient requirements. Avoid using high-phosphorus fertilizers, as many Australian native plants are sensitive to excessive phosphate, which can lead to toxicity. For container plants or young plants in poor soil, apply a balanced, slow-release fertilizer or a low-phosphorus liquid feed once in the spring.
Pruning and Harvesting Foliage
Pruning is important, especially if the goal is to maintain a bushy form and maximize foliage production. The plant responds well to heavy cutting, known as coppicing, which keeps the plant in a shrub-like state. To encourage a denser, multi-stemmed structure, cut the main stem back severely in the plant’s second year of growth.
For regular harvesting, cut stems when the foliage is mature, characterized by a firm, leathery texture. Immature, soft new growth wilts quickly after being cut, making it unsuitable for arrangements. Making clean cuts just above a leaf node stimulates new lateral growth, resulting in more stems for future harvests. Heavy structural pruning should occur in late winter or early spring before vigorous new growth begins.
Identifying and Treating Common Problems
While Silver Dollar Eucalyptus is generally robust, environmental stress and pests can cause issues. Overwatering commonly results in yellowing leaves or root rot if soil drainage is poor. Conversely, brown or crispy leaf tips often indicate underwatering or excessive salt buildup from fertilizer or hard water.
Pests like the red gum lerp psyllid and various boring insects, such as the eucalyptus longhorned borer, can target the plant. Psyllids cause leaf distortion and the appearance of waxy white structures called lerps, while borers attack the wood. For minor infestations, physically removing pests or applying neem oil can help control the problem.
Foliage-feeding caterpillars, like the omnivorous looper, can cause defoliation. If a large infestation occurs, hand-picking the caterpillars is effective. A targeted application of Bacillus thuringiensis (Bt) can also be used to eliminate the larvae. Monitoring the plant closely for initial symptoms allows for quick intervention.