What to Plant Under Crepe Myrtle in Australia: Top Companion Plants for Stunning Gardens

What to Plant Under Crepe Myrtle in Australia: Creating a Thriving Understorey

Crepe myrtles (Lagerstroemia spp.) are a favourite in Australian gardens for their stunning summer blooms, striking winter bark and adaptability to our diverse climates. But their open canopy makes them perfect for underplanting, adding colour, texture and suppressing weeds without competing for resources. If you’re wondering what to plant under crepe myrtle in Australia, this guide covers the best options tailored to local conditions.

Underplanting enhances your garden’s layered look, improves soil health and provides habitat for beneficial insects. Crepe myrtles thrive in full sun with well-drained soil, so choose companions that match: drought-tolerant once established, sun-loving or shade-tolerant (their canopy filters light in summer but allows full sun in winter dormancy).

Key considerations include your climate zone (cool temperate, warm temperate, subtropical or arid), soil type and tree size. Smaller cultivars like ‘Acoma’ (3-4m) suit courtyard gardens, while larger ones like ‘Natchez’ (6-8m) need more space.

Benefits of Underplanting Crepe Myrtles

• Weed suppression: Dense groundcovers block light to unwanted plants.
• Soil protection: Mulch-retaining plants prevent erosion and retain moisture.
• Visual appeal: Year-round interest with flowers, foliage and bark contrasts.
• Biodiversity: Attracts pollinators and birds, boosting garden ecology.
• Water efficiency: Drought-hardy combos reduce irrigation needs.

Best Plants for Under Crepe Myrtles by Climate Zone

Australia’s climates vary, so select accordingly. Use the Bureau of Meteorology zones or local nursery advice.

Cool Temperate Climates (e.g., Melbourne, Hobart, Zone 8-9)

Winter cold and wet summers demand hardy, frost-tolerant plants.

• Dianella tasmanica (‘Tasman Flax Lily’): Strappy evergreen foliage to 60cm, blue berries. Tolerates dry shade and -5°C frosts. Plant 50cm apart.
• Viola hederacea (Native Violet): Creeping groundcover with purple flowers year-round. Loves moist shade, spreads to 1m wide.
• Brunnera macrophylla: Heart-shaped leaves, blue forget-me-not flowers in spring. Grows 40cm tall, prefers partial shade.
• Mondo grass (Ophiopogon japonicus): Tough, grass-like tufts to 30cm. Evergreen, low-maintenance for edges.

Warm Temperate Climates (e.g., Sydney, Adelaide, Zone 9-10)

Mild winters, humid summers.

• Lomandra longifolia (‘Mat Rush’): Native strapper to 60cm, cream flower spikes. Ultra-tough, drought and salt tolerant. Space 60-80cm.
• Geranium ‘Rozanne’: Perennial cranesbill with violet-blue flowers from spring to autumn. Mounds to 50cm, self-seeding but not invasive.
• Ajuga reptans (Bugleweed): Glossy foliage, blue flower spikes. Fast-spreading groundcover for moist spots, 20cm tall.
• Hellebores (Lenten Rose): Winter-spring blooms in shade. Evergreen to 50cm, thrives under deciduous trees.

Subtropical Climates (e.g., Brisbane, Gold Coast, Zone 10-11)

Hot, humid with occasional frosts.

• Dianella caerulea: Blue flax lily with lilac flowers and berries. 70cm tall, humidity-proof.
• Mianthus simplicifolia (no longer used, wait: Plectranthus ciliatus): Purple foliage groundcover, shade-loving, 30cm.
• Salvia microphylla: Compact salvia with red/pink flowers. Attracts bees, 60cm, prune annually.
• Clivia miniata: Strappy orange flowers in spring. Bulbous, 60cm, dry-tolerant once established.

Arid and Mediterranean Climates (e.g., Perth, Adelaide inland, Zone 10-12)

Hot, dry summers; focus on water-wise natives.

• Myoporum parvifolium (Creeping Boobialla): Pink star flowers, soft mat to 20cm. Extremely drought-tolerant, spreads 1-2m.
• Grevillea ‘Poorinda Royal Mantle’: Groundcover grevillea with red toothbrush flowers. 50cm tall, bird-attracting, lime-tolerant.
• Westringia fruticosa ‘Low Horizon’: Compact native shrub to 50cm, white flowers. Wind and drought hardy.
• Gazania rigens: Daisy-like flowers in sun, closes at night. 30cm, perfect for dry banks.

Versatile All-Australia Options

These work nationwide under crepe myrtles:

• Daylilies (Hemerocallis hybrids): Trumpet flowers in summer, strappy leaves. 60-80cm, divide every 3-4 years.
• Agastache ‘Blue Fortune’: Anise-scented spikes of blue flowers. 90cm, butterfly magnet, prune to 30cm post-bloom.
• Lavandula angustifolia (English Lavender): Purple spikes, silver foliage. 50cm, full sun, well-drained.
• Sedum spectabile ‘Iceberg’: Succulent perennial with pink autumn flowers. 50cm, attracts butterflies.

Avoid water-hungry plants like impatiens or ferns, which struggle in summer dry.

How to Plant Under Your Crepe Myrtle

1. Timing: Autumn or early spring, when trees are dormant or lightly foliated.
2. Preparation: Mulch around trunk to 10cm deep (keep 10cm clear of bark). Gently fork soil, add compost or slow-release fertiliser (e.g., native mix, 50g/m²).
3. Spacing: Plant 30-60cm from trunk to avoid root competition. For groundcovers, closer for quick coverage.
4. Watering: Deep water weekly for first summer (20-30L per plant), then drought as per plant tolerance.
5. Mulch: 5-7cm organic layer post-planting to retain moisture and suppress weeds.

In pots under trees? Use raised planters with premium potting mix.

Maintenance Tips for Success

• Pruning: Lightly trim perennials post-flowering; avoid heavy cuts on natives.
• Fertilising: Low-phosphorus for natives (e.g., Yates Native Plant Food, March/September). General plants: balanced NPK in spring.
• Pests: Watch for aphids on new growth; hose off or use eco-oil. Slugs under hellebores? Use pet-safe baits.
• Watering: Mulch well; supplement in extreme heatwaves (>35°C).
• Renovation: Every 3-5 years, lift and divide clumps for vigour.

Common Mistakes to Avoid

• Planting too close to trunk: Causes rot.
• Overwatering: Leads to root rot in poorly drained soils.
• Ignoring climate: Tropical plants fail in cold snaps.
• Neglecting mulch: Increases evaporation in hot Aussie summers.

Designing Your Underplanting Scheme

Layer for impact:

• Ground layer: Creeping myoporum or viola.
• Mid layer: Dianella or salvia (40-70cm).
• Accent: Bulbs like daffodils for winter sun.

Combine colours: Crepe myrtle pinks/purples with blue dianella or red grevillea for contrast.

In small gardens, mass-plant 3-5 varieties in drifts. For larger trees, mix natives with exotics for low-maintenance appeal.

Final Thoughts

Underplanting crepe myrtles transforms a bare base into a vibrant, sustainable garden feature. Start small, observe conditions and expand. Local nurseries like Lambley Plants or Australian Plants Online offer region-specific advice.

With these picks, your crepe myrtle garden in Australia will thrive through seasons. Happy gardening!

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