Banksia marginata
silver banksia
Overview
Banksia marginata, the silver banksia, is an evergreen shrub to small tree in the family Proteaceae, widespread across southeastern Australia. It is highly variable, ranging from a low shrub of 3 feet (1 m) to a tree of 20 feet (6 m) or more depending on site. The narrow leaves are 0.5-1.5 inches (1.5-4 cm) long, dark green above and silvery white beneath, with a blunt or notched tip. From late summer to winter it bears pale yellow cylindrical flower spikes 2-4 inches (5-10 cm) long, each packed with hundreds of small flowers rich in nectar that draw honeyeaters, bees, and small mammals. Old spikes weather to grey woody cones holding the seed in hard follicles that often open only after fire. B. marginata grows in heath, woodland, and forest on sandy, acidic, sharply drained soils low in phosphorus, and tolerates wind, frost, and coastal salt. It is sensitive to high-phosphorus fertilizers and to root rot in wet or rich soil. The variable size and long flowering have made it a frequently grown banksia in native gardens.
Native Range
Native to southeastern Australia, including Victoria, Tasmania, New South Wales, and South Australia. It grows in heath, woodland, and open forest, from coastal sand to mountain slopes.Suggested Uses
Grown as a screen, windbreak, or specimen in native and coastal gardens, with smaller forms suited to containers. The winter flowers support nectar-feeding birds and bees. The woody cones and foliage are cut for native floral work.How to Identify
Appearance
Size & Dimensions
Height3' - 20'
Width/Spread3' - 12'
Reaches mature size in approximately 10 years
Bloom Information
Flowering runs from late summer through winter, roughly February to June in its native range, with some bloom at other times. The nectar-rich yellow spikes attract honeyeaters, lorikeets, bees, and small mammals. Each spike lasts several weeks before drying to a woody cone.
Detailed Descriptions
Foliage Description
dark green above, silvery white beneathGrowing Conditions
Sun Requirements
Requires 5-10 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
Care & Maintenance
Care Guide
Plants need full sun to light shade and sandy, acidic, sharply drained soil low in phosphorus. Water young plants to establish them, then water sparingly, as established shrubs tolerate drought. High-phosphorus fertilizers can kill banksias, so feeding is avoided or limited to native, low-phosphorus blends. The plant withstands frost, wind, and coastal salt but rots in wet or heavy ground. A coarse mulch keeps the surface roots cool. It resprouts after fire in some forms while others regrow only from seed.Pruning
Light pruning after flowering keeps the shrub compact and removes spent spikes. Some forms reshoot from a woody base after hard cutting, while tree forms tolerate only light tip-pruning. Pruning into bare old wood can fail to regrow.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
winter
Container Growing
✓ Suitable for container growing
Minimum container size: 7 gallons