Petrophile spp.

HardinessZones 9–11

Overview

Petrophile is a genus of about 60 evergreen shrubs in the family Proteaceae, known as conesticks and native to Australia, with the majority confined to the southwest of Western Australia. Plants form small to medium shrubs 1-10 feet (0.3-3 m) tall, with stiff leaves that range from needle-like to flat or divided, often sharply pointed. Small flowers are packed into dense, cone-like or globular heads at the branch tips or in the leaf axils, in cream, yellow, pink, or purple, with the individual flowers usually hairy. After flowering the heads develop into woody, persistent cones that hold the seed for years and often release it after fire. The genus grows in heath, shrubland, and open woodland on sandy, gravelly, nutrient-poor soils, and like other Proteaceae it is adapted to low-phosphorus ground and periodic burning. Some species regenerate from seed stored in the cones after fire, while others resprout from a woody base. Petrophile needs sharp drainage and full sun and is sensitive to phosphorus fertilizer. The persistent cones and prickly, often divided foliage give the shrubs year-round structure. Plants are slow-growing and uncommon in general cultivation.

Native Range

Petrophile is native to Australia, with most species concentrated in the southwest of Western Australia and a smaller number in the eastern states. Plants grow in heath, shrubland, and open woodland on sandy and gravelly, nutrient-poor soils.

Suggested Uses

Petrophile is grown in Australian native gardens, heath and habitat plantings, and low-phosphorus sandy beds in warm, dry climates. The persistent cones and structural foliage suit informal screens and dryland borders.

How to Identify

Look for stiff-leaved shrubs with needle-like, flat, or divided foliage and dense, cone-like or globular flower heads in cream, yellow, pink, or purple. After bloom the heads harden into woody cones that persist on the branches. The cone-like heads and woody fruit separate the conesticks from related shrubs.

Appearance

Size & Dimensions

Height1' - 10'

Width/Spread1' - 8'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Spring Summer

Flowering occurs mainly in spring and early summer, with timing varying across the genus. Dense cone-like heads of small hairy flowers open in cream, yellow, pink, or purple and draw native pollinators. The heads then harden into woody cones that hold seed for years.

Detailed Descriptions

Flower Description

cream, yellow, pink, or purple

Foliage Description

green to 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 Range5.0 - 6.5(Acidic)

357912

Soil Types

sand rocky

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

3-6 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Petrophile grows in full sun on sandy or gravelly, sharply drained, low-nutrient soil and tolerates heat and drought once established. The genus is sensitive to phosphorus like other Proteaceae and declines in rich or fertilized ground. Plants need good drainage and decline in wet, heavy soils, where the roots rot. Many species are adapted to fire, regenerating from seed held in the woody cones or resprouting from the base. Few pests trouble established plants in suitable conditions. Plants are slow to establish and need little water once settled in a warm, dry climate.

Pruning

Light pruning after flowering keeps shrubby plants compact, cutting above the woody cones. Species that resprout from a base tolerate harder cutting back, while others are pruned only lightly. Old woody cones can be left in place, as they hold the seed.