1 / 14

Banksia robur

swamp banksia

Proteaceae Eastern Australia

Attracts Pollinators Container Friendly

SunFull Sun – Part Shade

WaterMedium

HardinessZones 9–11

Overview

An evergreen shrub reaching 3-10 feet (1-3 m) tall and 5-10 feet (1.5-3 m) wide, with a spreading, sometimes sprawling habit from a woody rootstock. Leaves large and leathery, oblong to elliptic, 4-12 inches (10-30 cm) long and 1.5-4 inches (4-10 cm) wide, dark green above with a network of veins, paler and rusty-haired beneath, with coarsely serrated margins; new growth is covered in velvety rust-colored hairs. Flower spikes cylindrical, 2.5-6 inches (6-15 cm) tall, metallic blue-green in bud, opening to yellow-green and aging to golden then dull brown. Flowering occurs mainly autumn through winter but can appear year-round. Old spikes develop woody follicles holding winged seeds. Tolerates seasonally waterlogged soils. The foliage is coarse and the habit becomes open with age.

Native Range

Native to eastern Australia along the coast and near-coastal lowlands from central Queensland to southern New South Wales. Grows in wet heathland, swamp margins, and seasonally waterlogged sandy soils, usually below 1,000 feet (300 m).

Suggested Uses

Planted in wet or poorly drained native gardens, rain gardens, and bird-attracting plantings at 5-8 foot (1.5-2.4 m) spacing. Suits pond and bog margins where many shrubs fail in wet soil. Grows in large containers of at least 15 gallons (57 L) with moisture-retentive acidic mix.

How to Identify

Recognized by large leathery leaves 4-12 inches (10-30 cm) long with coarsely toothed margins and rusty-haired undersides, and cylindrical flower spikes that open blue-green before turning yellow-green. New growth is densely covered in rust-colored velvet. The combination of broad toothed leaves and tolerance of wet ground separates it from most Banksia spp. species.

Appearance

Size & Dimensions

Height3' - 10'

Width/Spread5' - 10'

Reaches mature size in approximately 4 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~5 weeks

Fall Winter

Flowers mainly March through August in its native range, with scattered spikes at other times. Spikes pass through metallic blue-green bud, yellow-green opening, and golden mature stages over several weeks. Each spike holds color for 4-6 weeks. Nectar-feeding birds visit the open flowers.

Detailed Descriptions

Flower Description

Blue-green opening to yellow-green and golden

Foliage Description

Dark green above, rusty beneath

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-8 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 Range4.5 - 6.5(Acidic)

357912

Soil Types

sand peat

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

3-5 years

Care & Maintenance

Care Guide

Water regularly until established; unlike most banksias, mature plants tolerate seasonally wet and boggy soils as well as periodic drying. Grows in full sun to part shade on sandy or peaty acidic soils. High-phosphorus fertilizers can damage the roots, a sensitivity shared across the Proteaceae. Mulch lightly to conserve surface moisture. Few serious pests occur. The woody rootstock allows recovery after cutting back or fire.

Pruning

Prune after flowering to maintain a compact habit, cutting stems back into green foliage. Plants resprout from the woody rootstock after hard pruning to near ground level. Removing spent spikes keeps the habit tidy. Cutting bare old wood without foliage produces slow regrowth.

Pruning Schedule

winter