Crepe myrtles (Lagerstroemia indica and hybrids) are beloved in Australian gardens for their vibrant summer blooms and striking winter bark. However, when it’s time to remove one, the stump often proves troublesome. These resilient trees can sprout vigorous suckers from their roots, turning a simple cut into a persistent battle. If you’re searching for how to kill crepe myrtle stump effectively, this guide provides practical, Australia-specific advice tailored to our diverse climates from subtropical Queensland to temperate Victoria.
Killing a crepe myrtle stump isn’t just about chopping it low—it’s about targeting the extensive root system to prevent regrowth. Expect the process to take weeks to months, depending on the method and tree size. Always prioritise safety: wear gloves, eye protection, and sturdy boots, and keep children and pets away during treatment.
Why Crepe Myrtle Stumps Regrow
Crepe myrtles have a tenacious root system that stores energy, enabling suckers to emerge even after felling. In Australia’s warm soils, especially in sandy or loamy conditions common in NSW and QLD, this regrowth is rampant. Factors like recent rain or fertiliser residue can fuel it further. Left unchecked, suckers can reach 1-2 metres in a season, forming a thicket.
Preparation Before Killing the Stump
- Cut the tree low: Use a chainsaw or loppers to sever the trunk 10-20 cm above ground. This exposes fresh cambium tissue for better herbicide uptake.
- Remove debris: Clear leaves, branches, and suckers to focus treatment on the stump.
- Timing: Act in late autumn or winter (May-August in southern states) when the tree is dormant, reducing stress on surrounding plants. Avoid spring growth flushes.
- Check regulations: In some local councils (e.g., parts of WA or NT), large tree removals need permits. Herbicides must comply with APVMA guidelines.
Method 1: Chemical Herbicides (Most Reliable)
Herbicides are the go-to for how to kill crepe myrtle stump completely. Glyphosate-based products like Roundup or Yates Zero are widely available at Bunnings and effective on woody stumps.
Step-by-Step:
- Drill holes: Use a 10-13 mm drill bit to bore 5-10 deep holes (10-15 cm) into the top of the stump and any major roots. Angle some downward for better penetration.
- Apply herbicide: Mix glyphosate at 1:1 with water (or follow label for stump killer concentrates like Toxin A or Garlon). Pour 50-100 mL per hole using a drenching bottle. For larger stumps (over 30 cm diameter), apply to the cut surface too.
- Seal: Cover with a black plastic bag secured by tape to prevent evaporation and animal access.
- Wait: Regrowth should yellow in 2-4 weeks; reapply if suckers appear. Full kill takes 4-8 weeks.
Pro Tip for Aussie Climates: In hot, dry areas like inland NSW, apply on a cool, overcast day to avoid rapid evaporation. Triclopyr (e.g., Brush-Off) excels on crepe myrtles in clay soils common in Melbourne gardens.
Safety Note: Glyphosate is safe when used as directed but rinse equipment thoroughly. Dispose of runoff responsibly to protect waterways.
Method 2: Mechanical Stump Grinding
For chemical-free removal, hire a stump grinder (around $200-400/day from equipment rentals).
How-To:
- Mark the area: Plan for a 1-1.5 m diameter hole, deeper than roots (up to 1 m).
- Grind systematically: Start at the edge, working inward to 30 cm below ground. Chip roots as encountered.
- Fill the hole: Backfill with soil mixed with compost, then mulch. Plant grass or a new shrub after 4-6 weeks.
Ideal for urban Sydney backyards where aesthetics matter. In rocky Adelaide soils, it prevents future suckering better than chemicals alone.
Method 3: Digging Out the Stump
Labour-intensive but thorough for small stumps (under 20 cm diameter).
- Tools: Shovel, mattock, axe.
- Process: Dig a trench 1 m around the stump, exposing roots. Sever laterals with loppers, then rock the stump free.
- Root ball: Aim to remove 50-70% of roots within 1 m radius.
Best in soft Perth sands but exhausting in heavy Victorian clays. Solarise the hole post-removal by covering with clear plastic for 4-6 weeks to kill remaining roots.
Method 4: Natural and Low-Chemical Options
Rock Salt or Epsom Salts
- Drill holes and fill with coarse rock salt or magnesium sulfate (Epsom salts, 1 kg per 30 cm stump).
- Water in lightly, cover with tarp.
- Takes 3-6 months; less effective in wet climates like Tassie but dehydrates roots in arid zones.
Copper Nails or Sulphate
- Hammer galvanised copper nails into the stump or apply copper sulphate solution.
- Slow-acting (6-12 months), folklore method with variable success on crepe myrtles.
Smothering
- Mow suckers weekly and cover the stump with 30-50 cm of mulch or black plastic weighted down.
- Starves roots of light and water; combine with girdling (remove bark ring 30 cm wide pre-cut).
These suit organic gardeners in Brisbane suburbs but may not fully kill large root systems.
Aftercare and Prevention
Once killed:
- Monitor for 6-12 months, spot-spraying suckers.
- Fill holes with topsoil to prevent waterlogging.
- Mulch to suppress weeds.
Prevent Future Issues:
- Choose non-suckering varieties like ‘Natchez’ or ‘Muskogee’ for new plantings.
- Plant in poor soils to limit vigour.
- Apply root barriers during planting in small gardens.
In Australian conditions, crepe myrtles thrive in full sun and free-draining soil (pH 5.5-7.5). Over-fertilising promotes suckering, so use slow-release natives blends sparingly.
Common Mistakes to Avoid
- Cutting too high: Suckers explode from the top.
- Treating in active growth: Herbicide translocates to roots less effectively.
- Ignoring weather: Heavy rain washes away chemicals.
- Skipping follow-up: One treatment rarely suffices.
FAQs
How long does it take to kill a crepe myrtle stump? 4-12 weeks chemically; instant mechanically.
Is glyphosate safe for Aussie pets? Yes, if dried and area avoided for 48 hours.
Can I replant immediately? Wait 2-3 months to ensure no regrowth.
What if the stump is near natives? Use mechanical methods to avoid drift.
By following these steps, you’ll conquer that stubborn crepe myrtle stump and reclaim your garden. For persistent cases, consult a local arborist—many offer stump treatments from $150.
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