Calothamnus quadrifidus grey

Grey One-Sided Bottlebrush

Botanical Name: Calothamnus quadrifidus 'Grey'
Family: Myrtaceae
Origin: South-Western Western Australia
Plant Type: Evergreen native shrub

Overview

Calothamnus quadrifidus 'Grey' is a striking grey-foliaged form of the common one-sided bottlebrush, prized for its soft, needle-like silver-grey leaves that provide year-round textural contrast in the landscape. Native to the sandplains and mallee scrubs of south-western Western Australia, it is supremely adapted to the hot, dry conditions of South Australia's Mediterranean climate. Deep crimson-red flower clusters erupt along one side of the stems in spring and summer, creating a vivid contrast against the silver foliage and drawing honeyeaters in abundance.

Key Features

• Mature Size: 1.5–2.5 m H x 1.5–2.0 m W
• Growth Rate: Moderate; 20–35 cm per year; open and arching with a naturally spreading, multi-stemmed bushy habit
• Foliage: Soft, linear to terete needle-like leaves, 2–4 cm long, in a distinctive silver-grey to blue-grey tone; foliage is dense and tactile, remaining attractive throughout the year
• Flowers: Deep crimson-red, claw-like staminal bundles arranged in one-sided clusters along stems; spring (August–November) with sporadic repeat flowering in summer; non-fragrant
• Seasonal Interest: Silver-grey foliage provides strong year-round contrast; bold red floral display peaks in spring and lifts the garden palette through the warmer months
• Wildlife Value: Excellent honeyeater plant — attracts New Holland honeyeaters, red wattlebirds and spinebills; flowers are rich in nectar and also visited by native bees and insects
• Tolerance: Highly drought-tolerant once established; frost hardy to approximately −5°C; heat-tolerant through extreme Adelaide summer conditions; wind-tolerant including exposed coastal ridges; tolerates poor sandy and light clay soils; coastal-tolerant in sheltered to semi-exposed positions
• Planting Density: Informal screen or wildlife buffer: plant 1.2–1.5 m apart (approx. 1–1.5 plants per metre run); mass planting or low windbreak: plant 80–100 cm apart (approx. 1.5–2 plants per metre run)
• Pet Friendly: Not recorded as toxic to dogs or cats; however, as with all needle-leaved shrubs, the stiff foliage tips may cause minor eye or skin irritation if animals brush through the plant — site away from pet play areas as a precaution

Where It Works Best

• Sunlight: Full sun preferred; performs best with at least 6 hours of direct sun daily; avoid deep shade which reduces flowering and causes open, leggy growth
• Soil: Excellent drainage is essential; thrives in sandy, gravelly or light loam soils; tolerates moderately poor clay-loam if not waterlogged; does not tolerate prolonged wet feet
• Water Needs: Establishment: water every 2–3 days for the first 6–8 weeks, then reduce to twice weekly for the remainder of the first summer (approximately 3–4 months total establishment period). Established: summer — deep water fortnightly during hot dry spells (December–March); winter — rainfall usually sufficient, supplemental irrigation rarely needed
• Maintenance: Low maintenance; tip prune lightly after flowering to encourage bushiness and prevent woodiness; avoid cutting back hard into old wood; remove dead flower clusters if desired for aesthetics; no regular fertilising needed — a light native-formula application in spring is optional
• Lifespan: 15–30+ years with appropriate drainage and minimal interference
• Climate Zones: Ideal for Adelaide's Mediterranean and dry temperate zones including northern and southern suburbs, the Barossa and Clare Valley regions, Fleurieu Peninsula, Kangaroo Island coastal areas, and lower Adelaide Hills (below frost-prone gullies); also suited to hot inland areas such as the Riverland where drainage is adequate
• Soil pH: Mildly acid to neutral preferred (pH 5.5–7.0); tolerates slightly alkaline soils to pH 7.5 with adequate drainage

Landscape & Design Ideas

• Plant in drifts of 3–5 along a boundary fence as a low-maintenance native screen that provides wildlife habitat, wind filtration and striking silver-red seasonal colour
• Use as a bold foliage contrast plant in a dry Mediterranean garden alongside Westringia, Lomandra and Eremophila — the grey foliage bridges blue-greens and silvers beautifully
• Incorporate into a dedicated bird garden or wildlife corridor planting with other honeyeater-attracting species such as Grevillea 'Robyn Gordon' and Banksia marginata for season-long nectar availability

Why You Will Love It

If you want a plant that genuinely earns its place in a South Australian garden, Calothamnus quadrifidus 'Grey' delivers on every count — stunning silver-grey texture all year, a jaw-dropping burst of crimson in spring, zero fuss once established, and a revolving door of honeyeaters that will have you reaching for your binoculars. It thrives precisely where other plants struggle: baking hot sites, sandy or gravelly soils, dry summers and exposed positions. This is tough, beautiful, and unmistakably Australian.