Introducing the Blue Blue Crepe Myrtle
If you’re chasing a splash of cool colour in your sun-drenched Australian garden, the Blue Blue crepe myrtle (Lagerstroemia indica ‘Blue Blue’) delivers. This compact cultivar stands out with its clusters of delicate, crinkled lavender-blue flowers that evoke a soft blue hue – rare among crepe myrtles dominated by pinks, purples and whites. Blooming profusely from late spring through autumn, it adds months of interest while handling our harsh summers like a champ.
Native to Asia but a staple in Aussie landscapes since the 19th century, ‘Blue Blue’ grows to about 3-4 metres tall and wide, making it ideal for suburban backyards, street plantings or pots. Its smooth, peeling bark in winter reveals mottled cinnamon tones, and vibrant orange-gold autumn foliage seals its four-season appeal. Best suited to warm climates (USDA zones 8-10, aligning with much of coastal Australia), it tolerates light frost but shines in humid subtropics like Queensland and northern NSW.
Why Choose Blue Blue for Australian Conditions?
Australia’s diverse climates demand tough plants, and ‘Blue Blue’ fits the bill:
- Heat and Drought Tolerance: Thrives in 40°C+ summers, with deep roots seeking moisture.
- Humidity Resistance: Mildew-resistant compared to older varieties.
- Versatility: Scales from small gardens (prune to 1.5m) to feature trees.
In cooler southern regions like Melbourne or Adelaide, plant in sheltered spots; it’ll still flower reliably with protection.
Selecting and Planting Your Blue Blue Crepe Myrtle
Choosing Healthy Stock
Look for tubestock or 20-30cm pots from reputable nurseries. Inspect for:
- Sturdy trunks without girdling roots.
- Glossy green leaves free of spots.
- No signs of powdery mildew (white coating).
Spring (September-November) is prime planting time in most areas, avoiding summer heat stress.
Site Preparation
Crepe myrtles crave full sun – at least 6 hours daily – for maximum blooms. They prefer:
- Well-Drained Soil: Sandy loam or clay improved with gypsum (add 1-2kg per square metre for heavy soils).
- pH: Slightly acidic to neutral (5.5-7.0).
- Spacing: 3-4m apart for trees; 1-2m for hedges.
Dig a hole twice as wide as the root ball and 10cm shallower. Mix in compost or cow manure (20% by volume) and a handful of slow-release native fertiliser. Water deeply post-planting (20-30L), then mulch with 5-7cm of organic bark to suppress weeds and retain moisture.
Pro Tip: In pots, use a 40-50cm diameter container with premium potting mix. Elevate for drainage.
Essential Care for Thriving Blue Blue Crepe Myrtles
Watering
Establish young plants with weekly deep watering (30-40L per tree) for the first summer. Mature specimens are drought-hardy but perform best with fortnightly soaks during prolonged dry spells. Avoid overhead watering to prevent fungal issues.
Fertilising
Feed sparingly to avoid soft growth prone to pests:
- Spring: Balanced NPK 10-10-10 granular (100g per mature tree), or native blend low in phosphorus.
- Summer: High-potassium booster (e.g., potash) for blooms.
- Apply 10cm from trunk, water in well.
Over-fertilising leads to fewer flowers, so err on the light side.
Pruning Mastery
Pruning is crepe myrtle’s secret weapon for shape and blooms. Aussies often battle ‘crepe murder’ – excessive topping that ruins form. Instead:
- Winter Prune (June-August): Remove suckers at base, thin crowded branches, cut back to outward-facing buds. Aim for vase shape.
- Summer Tip Prune: Pinch tips post-bloom to encourage branching.
- Tools: Sharp secateurs, loppers; disinfect between cuts.
For hedges, prune 2-3 times yearly to 2m height. This promotes masses of next-season’s blue flowers on new wood.
Mulching and Soil Health
Replenish mulch annually, keeping it away from the trunk to avoid rot. Test soil every 2-3 years; add dolomite if pH drops below 5.5.
Pests, Diseases and Troubleshooting
‘Blue Blue’ is relatively pest-free but watch for:
- Aphids/Scale: Hose off or use eco-oil (dilute per label, apply evenings).
- White Lace Maggots: Larvae cause galls; prune affected tips.
- Powdery Mildew: Grey-white powder in humid conditions. Improve air flow, apply sulphur spray.
- Root Rot: From poor drainage; ensure free-draining soil.
In wet tropics, sooty mould follows sap-suckers – treat insects first.
Common Issues:
| Problem | Cause | Fix |
|---|---|---|
| Few Flowers | Excess nitrogen, shade | Balance fertiliser, more sun |
| Leggy Growth | Insufficient light/pruning | Full sun, hard prune |
| Yellow Leaves | Waterlogging/iron deficiency | Improve drainage, chelated iron |
Propagation: Grow Your Own Blues
Home propagation is straightforward:
- Cuttings: Semi-hardwood, 10cm tips in summer. Dip in rooting hormone, pot in perlite mix. 4-6 weeks to root under mist.
- Seed: Scarify and sow in trays; slow (2-3 years to bloom) and variable colour.
Share with mates – it’s rewarding and cost-effective.
Landscaping with Blue Blue Crepe Myrtle
This versatile beauty stars in:
- Borders: Mass plant for blue haze effect.
- Espalier: Train against walls in small spaces.
- Pots/Patios: Compact form for balconies.
- Natives Mix: Pair with bottlebrush or grevillea for contrast.
Companions: Lavender for pollinators, dianella for groundcover, agapanthus for height match. In drought gardens, underplant with kangaroo paw.
Design a 4x4m bed: Centre with ‘Blue Blue’, edges with white ice plant, mulch heavily.
Where to Buy in Australia
Nurseries like Bunnings, local independents or specialists (e.g., NuGrow, Yates) stock ‘Blue Blue’ seasonally. Online from Daleys Fruit or Plantmark. Expect $20-50 for starters.
Final Thoughts
The Blue Blue crepe myrtle brings elusive cool tones to fiery Aussie summers, rewarding patient gardeners with effortless beauty. Plant right, prune smart, and enjoy its lavender-blue magic for decades. Happy gardening!
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