Dealing with Brambles, Ivy or Woody Weeds?
Fluroxypyr is the active ingredient that makes brushwood killers work. Here’s what it does, where to use it, and how it compares to other herbicides.
Fluroxypyr at a Glance
Fluroxypyr belongs to the same family as MCPA and 2,4-D — they’re all synthetic auxin herbicides. But fluroxypyr has a particular strength: it’s exceptionally effective on woody and semi-woody weeds that standard lawn herbicides struggle with. If you’ve bought a “brushwood killer” from a garden centre, fluroxypyr is almost certainly the active ingredient.
What Does Fluroxypyr Control?
The key advantage of fluroxypyr over glyphosate for brushwood work is selectivity. Because it’s a broadleaf-specific herbicide, you can spray it near grass without killing the turf. This makes it ideal for clearing brambles from lawn edges, boundaries and areas where grass grows among the weeds.
How to Use Fluroxypyr Effectively
There are two main application methods:
Foliar spray (most common): Dilute the concentrate according to the label and spray onto actively growing leaves. The product is absorbed through the foliage and transported throughout the plant, including the roots. For brambles and large woody growth, cut back the worst of the top growth first, wait for 30-60cm of fresh regrowth, then spray. Fresh growth absorbs herbicide far more effectively than old, woody stems.
Stump treatment: For trees, large shrubs or thick bramble root crowns, cut the stem as close to the ground as possible and immediately apply neat (undiluted) brushwood killer to the fresh cut surface. The exposed vascular tissue absorbs the herbicide directly into the root system. This must be done within minutes of cutting — the plant quickly seals the wound.
Timing: Apply between May and October when the target weeds are in full leaf and actively growing. Like all systemic herbicides, fluroxypyr needs the plant’s own transport system to carry it to the roots. In winter, that system is largely shut down. Check the rain forecast — you need at least 6 hours dry after spraying.
Fluroxypyr vs Other Herbicides
In practice, many brushwood killer products combine fluroxypyr with triclopyr. The combination provides broader spectrum control than either ingredient alone. If you’re clearing an overgrown garden with a mix of woody and herbaceous weeds, a combination product gives the best results.
Safety and Environmental Considerations
- Spray drift: Apply on calm days only. Even a light breeze carries fine spray particles onto nearby plants. Use a coarse spray setting and keep the nozzle close to the target
- Garden plants: Fluroxypyr kills all broadleaf plants, not just weeds. Keep it well away from roses, shrubs, vegetables and flower beds
- Water: Don’t apply near ponds, streams or ditches. Fluroxypyr is toxic to aquatic organisms. Maintain a buffer zone of at least 5 metres from any water body. See our wildlife and water safety guide for more
- Pets and children: Keep off treated areas until the spray has fully dried (2-4 hours in good conditions). See our pet safety guide for detailed drying times
- Compost: Unlike clopyralid, fluroxypyr doesn’t persist in compost for extended periods. Treated vegetation can be composted after full die-back, though waiting a full season is safest
Frequently Asked Questions
Can I use fluroxypyr on my lawn?
At the recommended rate, fluroxypyr is safe on established grass. However, it’s not typically sold as a lawn weed killer — products containing MCPA or mecoprop-P are more common and cost-effective for lawn use. Fluroxypyr is primarily marketed for brushwood and woody weed control. For the best lawn weed killers, see our dedicated guide.
How long does fluroxypyr take to work?
You’ll see wilting and leaf curling within 1-2 weeks. Full die-back of woody growth takes 3-6 weeks depending on the size of the plant and growing conditions. Large bramble root systems may need a second application on any regrowth. If results seem slow, check our troubleshooting guide.
Is fluroxypyr the same as triclopyr?
No, they’re different chemicals, but they’re closely related and often combined in brushwood killer products. Both are synthetic auxin herbicides effective on woody weeds. Triclopyr is slightly more effective on some species, while fluroxypyr has a broader range. The combination works better than either alone.
Will fluroxypyr kill tree stumps?
Applied as a stump treatment (neat concentrate on a freshly cut surface), it can prevent regrowth from many species. For large or established trees, a dedicated stump killer or glyphosate stump treatment may be more reliable. Apply within minutes of cutting for best absorption.
Can I mix fluroxypyr with glyphosate?
Don’t mix herbicides unless the label specifically advises it. While some professional applicators do use combinations, the chemistry is complex and amateur mixing can reduce effectiveness or create unexpected reactions. Use each product separately as directed.
When is the best time to spray brambles with brushwood killer?
June to September, when brambles are in full leaf and actively growing. Cut back the worst of the growth first, wait 4-6 weeks for fresh leafy regrowth, then spray thoroughly. Fresh growth absorbs the herbicide much more effectively than old, woody canes. Check our timing guide for seasonal advice.
Need to Clear Woody Weeds?
Our weed killers range includes products effective on brambles, ivy and woody scrub. For the toughest jobs, glyphosate-based treatment gets the roots.
