Plectranthus Argentatus

Silver Spurflower / Silver Plectranthus / Silver Spur / Silverspur Flower

Botanical Name: Plectranthus argentatus
Family: Lamiaceae
Origin: Eastern Australia
Plant Type: Evergreen shrub

Overview

A standout silver foliage shrub that brightens Adelaide and South Australian gardens, thriving where many plants struggle. Plectranthus argentatus forms soft, velvety mounds of silvery-grey leaves that glow in light shade and pair beautifully with natives and Mediterranean plants. In late summer to autumn, airy spires of pale lavender-white flowers add extra texture and pollinator interest.

Key Features

• Mature Size: 0.8–1.2 m H × 1.0–1.5 m W (rounded, spreading habit)
• Growth Rate: 30-60 cm per year under good conditions
• Foliage: Silvery-grey, velvety leaves (felted) with fresh silvery-lime tints on new growth; colour intensifies in cool, dry light
• Flowers: Pale lavender to white sprays on upright spikes late summer–autumn
  
• Seasonal Interest: Year-round silvery foliage for contrast and softness, with a late summer–autumn flower display that extends interest into the dry months
• Wildlife Value: Attracts Bees, Attracts Butterflies; Good for Pollinators
• Tolerance: Drought-Tolerant (once established), Heat-Tolerant (prefers afternoon shade), Coastal-Tolerant (sheltered), Wind-Tolerant, Light frost tolerant; avoid heavy, waterlogged clay
• Planting Density: Shrub borders: 0.6–0.8 m apart (≈ 1.2–1.6 plants/m). Mass planting: 1–2 plants per m²
• Pet Friendly: Generally regarded as non-toxic to pets

Where It Works Best

• Sunlight: Part shade to morning sun; protect from harsh afternoon summer sun
• Soil: Well-drained sandy or loam soils; improve heavier soils with compost/grit
• Water Needs: Establishment: 2 deep soaks/week for 8–12 weeks. Established: deep soak every 10–14 days in summer; monthly in winter if dry
• Maintenance: Tip-prune after flowering to keep compact; remove spent spikes; mulch in spring; feed lightly in early spring
• Lifespan: 5-10+ years
• Climate Zones: Suited to temperate & Mediterranean SA, including coastal Adelaide
• Soil pH: Slightly Acid to Neutral (tolerates mildly alkaline if drainage is sharp)

Landscape & Design Ideas

• Light up dry shade under open trees or on the south/west side with a silver, low-water contrast
• Coastal & Mediterranean mixes with lomandra, westringia, rosemary and salvias for texture and drought sense
• Feature pots in bright shade—silver foliage pops against dark containers and paving

Why You Will Love It

This is the easy silver your South Australian garden has been missing—soft, luminous foliage that behaves in heat and light frost, with bonus late-season flowers. It’s versatile, water-wise and low-maintenance, delivering designer contrast without the fuss.