Understanding Crepe Myrtle Suckers
Crepe myrtles (Lagerstroemia spp.) are beloved in Australian gardens for their spectacular summer blooms, striking autumn foliage and attractive winter bark. Native to Asia but perfectly suited to our warm climates, these deciduous trees or large shrubs can reach 3-10 metres tall, depending on the variety. However, one common frustration for Aussie gardeners is crepe myrtle suckers – vigorous shoots emerging from the base of the trunk or roots.
Suckers are basal shoots that sap energy from the main tree, leading to a bushy, multi-stemmed appearance rather than the elegant single-trunk form many desire. Left unchecked, they can overwhelm the tree, reduce flowering and make maintenance harder. In Australia’s diverse climates, from subtropical Queensland to temperate Victoria, suckers are especially prevalent in stressed trees exposed to drought, poor soil or injury.
This guide provides practical, step-by-step advice tailored to Australian conditions, helping you keep your crepe myrtles looking their best.
Why Do Crepe Myrtles Produce Suckers?
Suckers form as a survival mechanism. Here’s what triggers them in our gardens:
- Root or trunk damage: Lawn mowers, whipper snippers or accidental injury to the base prompts the tree to produce suckers for regrowth.
- Stress factors: Drought, waterlogging, nutrient deficiencies (especially nitrogen) or root competition from turf/grasses.
- Improper pruning: ‘Stubbing’ branches too high (known as crepe murder) shocks the tree into suckering.
- Grafted varieties: Common in Australia, suckers often arise from the rootstock below the graft union, which is more vigorous than the scion.
- Age and neglect: Older trees (over 10 years) or those in compacted clay soils common in Sydney or Melbourne basins sucker more.
In humid subtropical areas like Brisbane, fungal issues or wet feet exacerbate suckering, while in drier inland regions like Adelaide, water stress is the culprit.
Best Time to Remove Crepe Myrtle Suckers in Australia
Timing is crucial to avoid stressing the tree further. In Australia:
- Late winter to early spring (July-September): Ideal for most regions. Trees are dormant, reducing sap flow and disease risk. Prune after any frost risk in cooler southern areas.
- Avoid summer (December-February): High heat and active growth lead to excessive bleeding and regrowth.
- Regional tips:
- Queensland/Northern NSW: Prune June-August before the wet season.
- Southern states (VIC, SA, TAS): Wait until August-September to dodge frosts.
- Arid zones (inland NSW, WA): Any cooler months, but monitor for heatwaves.
Regular checks every 4-6 weeks during the growing season help catch suckers early.
Step-by-Step Guide: How to Remove Crepe Myrtle Suckers
Tools needed: Sharp secateurs, loppers, pruning saw, gloves, mulch and a herbicide like glyphosate (if required).
Step 1: Identify Suckers
Distinguish suckers from water sprouts (vertical shoots from branches). Suckers emerge low on the trunk (below 30cm) or from roots, often more vigorous with lighter leaves than the main canopy.
Step 2: Hand-Pull Small Suckers
- For shoots under 15cm: Grasp at soil level and pull firmly, twisting to remove the entire basal plate. Do this after rain when soil is moist.
- Moisten soil first to ease extraction without damaging roots.
Step 3: Prune Larger Suckers
- Cut flush with the trunk or root using clean, sharp tools at a 45-degree angle.
- For root suckers: Trace back to origin and sever at the root junction.
- Sterilise tools with methylated spirits between cuts to prevent disease spread.
Step 4: Apply Herbicide (Optional but Effective)
For stubborn suckers, especially on grafted trees:
- Immediately paint undiluted glyphosate on the fresh cut with a brush.
- Avoid spraying – it can damage nearby plants.
- Repeat every 4 weeks if regrowth occurs. In organic gardens, use vinegar-based solutions, though less effective.
Step 5: Aftercare
- Mulch around the base with 5-10cm of organic matter (sugar cane or lucerne hay) to suppress regrowth and retain moisture.
- Water deeply (20-30L per tree weekly) during establishment or dry spells.
- Fertilise sparingly with a low-nitrogen slow-release formula (e.g., native plant food) in spring.
Expect multiple treatments; persistence pays off.
Prevention Strategies for Crepe Myrtle Suckers
Prevention beats cure. Here’s how to minimise suckers long-term:
- Planting right: Choose grafted varieties suited to your zone (e.g., ‘Natchez’ for full sun in warmer areas). Plant in well-drained soil with 1-2m clearance from lawns.
- Mulch religiously: Keep a 10cm mulch ring weed-free to 1m radius.
- Proper pruning: Thin canopy in winter, never topping. Aim for vase-shaped structure.
- Water wisely: Deep, infrequent watering mimics natural rainfall. Install drip irrigation in sandy soils.
- Soil prep: Test pH (ideal 5.5-6.5); amend heavy clays with gypsum.
- Variety selection: Less sucker-prone options include ‘Sioux’ or ‘Muskogee’ – check local nurseries for AUS-adapted cultivars.
In coastal NSW or QLD, elevate planting mounds by 20-30cm to combat wet summers.
Common Mistakes to Avoid
- Cosmetic cuts: Mowing over suckers spreads them via fragments.
- Over-fertilising: High-nitrogen feeds promote suckering.
- Ignoring rootstock: On grafted trees, paint graft unions with white tree paint for protection.
- Planting in shade: Crepe myrtles need 6+ hours full sun; shade stresses them into suckering.
- Neglecting pests: Aphids or scale weaken trees, indirectly causing suckers. Hose off or use eco-oil.
Australian Varieties and Their Sucker Tendencies
Popular low-sucker options:
| Variety | Height | Flower Colour | Sucker Rating | Best Regions |
|---|---|---|---|---|
| ’Natchez’ | 6-8m | White | Low | QLD, NSW, VIC |
| ’Dynamite’ | 4-6m | Red | Medium | All warm Aus |
| ’Acoma’ | 3-4m | Lavender | Low | Cooler south |
| ’Biloxi’ | 4-5m | Pink | Low-Medium | Subtropical |
Source rootstock suckers are common in cheaper imports; opt for reputable Aussie growers like NuCizia Nursery.
Troubleshooting Persistent Suckers
If suckers persist:
- Check for girdling roots: Dig gently and sever circling roots.
- Consider removal: For severe cases, excavate and transplant, but success is low.
- Professional help: Arborists can perform root barriers.
Healthy crepe myrtles reward with masses of flowers up to 20cm across, attracting bees and birds.
Final Tips for Thriving Crepe Myrtles Down Under
- Frost protection: In Zone 9 south, cover young trees.
- Drought tolerance: Once established (2-3 years), they cope with 500mm annual rain.
- Companion planting: Pair with salvias or agastaches for pollinator magnets.
By tackling crepe myrtle suckers promptly, your garden will boast show-stopping trees year-round. Happy gardening!
(Word count: 1128)