Calothamnus spp.

one-sided bottlebrush

Attracts Pollinators Deer Resistant Drought Tolerant Container Friendly

HardinessZones 9–11

Overview

Calothamnus spp. is a genus of about 40 evergreen shrubs in the myrtle family, all native to Western Australia. Plants range from low, spreading mounds to upright shrubs 3-10 feet (0.9-3 m) tall, with crowded, needle-like or narrow leaves that are often gray-green and slightly rigid. The flowers are the defining feature: clusters of bristle-like red stamens, sometimes cream or yellow, borne in dense, one-sided spikes along the older wood, which gives rise to the common name one-sided bottlebrush. Woody seed capsules follow and are held on the stems for years, opening after fire. Flowering is mainly in spring, though scattered bloom occurs at other times. The genus grows on sandy or gravelly soils in heath and scrub and tolerates drought, wind, and coastal exposure once established. Plants are frost-tender, damaged below about 25 F (-4 C), and they decline on heavy, poorly drained ground. The red-flowered species draw nectar-feeding birds. Some botanists now place these species within Melaleuca spp., though many references and nurseries keep them under Calothamnus spp.. Most need full sun and free-draining soil to flower freely and hold a dense habit.

Native Range

Native to Western Australia, where the genus is concentrated in the sandplains, heaths, and scrub of the southwest.

Suggested Uses

Planted in dry, sunny gardens, coastal plantings, and native or wildlife gardens for the red flowers and bird traffic. Suited to gravel and low-water landscapes. Plants are not reliable in cold-winter regions or on wet, heavy soils.

How to Identify

Recognized by evergreen shrubs with crowded, narrow to needle-like leaves and one-sided clusters of bristly red stamens set against the stems. Woody, rounded seed capsules persist on older wood. The flower spikes appear along the branches rather than only at the tips.

Appearance

Size & Dimensions

Height3' - 10'

Width/Spread3' - 8'

Colors

Flower Colors

red

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~6 weeks

Spring

Flowering peaks in spring, with scattered blooms through the year in mild climates. The red, brush-like stamen clusters last several weeks and are followed by woody capsules. Nectar at the flower bases draws honeyeaters and other birds.

Detailed Descriptions

Flower Description

red, sometimes cream or yellow

Foliage Description

gray-green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0(Neutral)

357912

Soil Types

sand rocky

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

tender

Time to Maturity

3-5 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Plants grow in full sun on light, sharp-draining sandy or gravelly soil low in phosphorus. They establish from container plants set out in the cooler months, after which they tolerate drought, heat, and coastal wind. Phosphorus-rich fertilizers harm these myrtle-family plants, so feeding is kept minimal. Frost below about 25 F (-4 C) damages growth, limiting them to mild, frost-free zones. Wet or heavy soils cause root rot. Established shrubs need little water beyond natural rainfall in their climate.

Pruning

Light tip pruning after flowering keeps plants bushy and within bounds. Cutting back into old, leafless wood is risky, as these shrubs are slow to reshoot from bare stems. Spent flower clusters and capsules can be left in place or trimmed for appearance.