A weed killer for lawn use is a chemical or natural solution that targets weeds without ruining your turf. Right? The best weed killer for lawns in Australia depends on three things: the weed species you have, your grass type, and the time of year.
This guide walks Aussie lawn owners through every option, from selective herbicides to pre-emergent weed killers, so you pick the right product the first time.
Australian lawns deal with a wide mix of pesky lawn weeds across the year. Bindii pops up in winter. Summer Grass and Crowsfoot Grass appear when the soil warms. Onion weed, creeping oxalis, ground ivy and lambs tongue all turn up in patches where the lawn thins out.
For weed IDs with photos, see ALC’s Guide to the Most Common Lawn Weeds.
What Are the Types of Lawn Weed Killers
Lawn weed killer products split into four groups. Knowing which group you need stops you from killing the lawn instead of the weeds.
1. Selective Weed Killers
A selective herbicide kills certain weeds while leaving the lawn grass alone. Selective weed killers are the standard pick for treating broadleaf weeds like bindii, clover, creeping oxalis and lambs tongue inside an established lawn.
Bow and Arrow Weed Killer Herbicide 500 mL is a broadleaf selective with three active ingredients: MCPA, Clopyralid and Diflufenican. It targets bindii (Soliva sessilis), white clover, plantain (lambs tongue), capeweed, cat’s ear, cudweed and creeping oxalis.
The 500 mL bottle covers 1,000 m² at the label rate of 50 mL in 5 litres of water per 100 m².
Safe on Sir Walter, Sapphire and other soft-leaf buffalo lawns, plus zoysia and couch. The ideal application window per the label is May to August, when broadleaf weeds are actively growing in cooler weather.
Always read the label, and test a small patch first on unknown buffalo strains, since older common buffalo can be more sensitive to MCPA than soft-leaf modern cultivars.
2. Non-Selective Weed Killers
A non selective weed killer takes out everything green, lawn grass, garden plants and the weeds. Use non selective herbicides only on garden beds, paths, driveway cracks, or when you plan to redo the entire lawn from scratch.
Spray on a still day so the chemical does not drift onto desirable plants. A weed wand is handy for spot-treating individual weeds with a non-selective product without hitting nearby grass.
3. Pre-Emergent Weed Killers
Pre emergent weed killers stop weed seeds from sprouting. The pre emergent herbicide forms a thin barrier in the topsoil that interrupts germination. This is the smartest way to control weeds like Winter Grass and Summer Grass before they show.
OxStar Lawn Fertiliser & Weed Preventer 20 kg (also available as an 8 kg pack for smaller yards covering 200 m²) uses Oxadiazon to block Winter Grass, Summer Grass, Creeping Oxalis and Crowsfoot Grass while feeding the lawn at the same time.
The 20 kg bag covers 500 m². Apply at 4 kg per 100 m² for Winter Grass and Creeping Oxalis, or 3 kg per 100 m² for Summer Grass and Crowsfoot. Water in with at least 10 mm of irrigation.
Avoid temperatures above 32°C and do not apply to wet foliage. Safe on Buffalo, Common Couch, Blue Couch, Saltwater Couch, Kikuyu, Zoysia and hybrid couches (not Santa Ana).
Pro Tip: When SEQ soil temperatures consistently reach 10°C, weed seeds start to germinate. That’s your trigger to lay down OxStar before they emerge.
4. Post-Emergent Weed Killers
Post emergent weed killers work on actively growing weeds you can already see. Most weed killers in this group are sprayed onto leaves and absorbed into the plant.
Tempra Nutgrass Killer 25 g is the go-to for nutgrass and Mullumbimby couch in buffalo, couch, kikuyu, and zoysia lawns. The active ingredient is Halosulfuron-methyl. A 25 g pack covers 1,900 m². It is selective, so it leaves the lawn intact while killing the sedge.
For a recovery bundle that covers fungal disease, broadleaf weeds, and nutgrass in one go, the Lawn Treatment Pack (Impala, Bow & Arrow, Tempra) is the ALC team’s pick.
Herbicide Comparison Table
| Product | Type | Active Ingredient | Targets | Coverage | Safe On | Price |
| Bow and Arrow 500 mL | Selective post-emergent | MCPA, Clopyralid, Diflufenican | Bindii, clover, plantain, capeweed, cat’s ear, cudweed, creeping oxalis | 1,000 m² | Buffalo (soft-leaf), couch, kikuyu, zoysia | $60 |
| Tempra Nutgrass Killer 25 g | Selective post-emergent | Halosulfuron-methyl | Nutgrass, Mullumbimby couch | 1,900 m² | Buffalo, couch, kikuyu, zoysia | $60 |
| OxStar 20 kg | Pre-emergent + fertiliser | Oxadiazon | Winter Grass, Summer Grass, Creeping Oxalis, Crowsfoot Grass | 500 m² | Buffalo, Common/Blue/Saltwater Couch, Kikuyu, Zoysia, hybrid couches (not Santa Ana) | $180 |
| OxStar 8 kg | Pre-emergent + fertiliser | Oxadiazon | As above | 200 m² | As above | $100 |
| Lawn Treatment Pack — Impala, Bow & Arrow, Tempra | Recovery bundle (fungicide + 2 herbicides) | Multiple | Fungal disease, broadleaf weeds, nutgrass | Up to 1,900 m² | Buffalo, couch, zoysia | $200 |
Australian Seasonal Application Calendar
Timing changes the result. A pre emergent put down a month late will not work. A post-emergent sprayed in 38°C heat burns the lawn.
Autumn (March to May)
- Apply OxStar pre emergent at 4 kg per 100 m² to block Winter Grass and Creeping Oxalis before germination, ideally as soil temps approach 10°C.
- The lawn should be moist but not wet.
- Water in OxStar with at least 10 mm of irrigation.
Winter (June to August)
- Spray Bow & Arrow on actively growing broadleaf weeds. May to August is the ideal window per the product label.
- Hand-pull or spot-spray bindii before flowers form, since this is when the prickly seed develops.
- Avoid heavy spraying when grass is dormant. Wait for active growth.
- Don’t water in for several days after applying Bow & Arrow.
Spring (September to November)
- Apply OxStar pre emergent at 3 kg per 100 m² for Summer Grass and Crowsfoot Grass.
- Continue to tackle broadleaf weeds with Bow & Arrow while weeds are actively growing.
- Watch for nutgrass emerging in warmer pockets.
Summer (December to February)
- Spot-treat nutgrass and Mullumbimby couch with Tempra.
- Spray in early morning or late afternoon, never above 32°C.
- Skip if rain is forecast within 4 to 6 hours unless the label notes rain resistance.
For the full year-by-month rhythm, see ALC’s Yearly Lawn Care Plan.
Safety by Grass Type
Not every weed killer suits every lawn. Use this matrix before you spray.
| Grass Type | Bow and Arrow | Tempra | OxStar |
| Sir Walter Buffalo | Safe at label rate | Safe | Safe |
| Sapphire Buffalo | Safe at label rate | Safe | Safe |
| Wintergreen Couch | Safe | Safe | Safe |
| IronCutter Elite Hybrid Bermuda | Safe | Safe | Safe (hybrid couches, not Santa Ana) |
| Empire Zoysia | Safe | Safe | Safe |
| Nara Native Zoysia | Safe | Safe | Safe |
| Augusta Zoysia | Safe | Safe | Safe |
Older common buffalo (non soft-leaf) is sensitive to MCPA, so check the label and test a small patch before spraying any selective weed killer on unknown buffalo lawns.
How to Choose the Right Weed Killer for Your Lawn
Five steps to land on the best weed killer for your situation.
- Identify the weed. Broadleaf weeds (bindii, clover, lambs tongue, ground ivy, creeping oxalis) need a selective broadleaf herbicide. Grassy weeds (Winter Grass, Summer Grass, Crowsfoot Grass) need a pre-emergent. Sedges (nutgrass, Mullumbimby couch) need Halosulfuron.
- Match the product to your grass type. Use the safety matrix above. When in doubt, ring ALC on 07 5541 7000.
- Size up the lawn. A 25 g pack of Tempra covers 1,900 m². A 500 mL bottle of Bow & Arrow covers 1,000 m². A 20 kg bag of OxStar covers 500 m². An 8 kg bag covers 200 m². Buy the size that matches your yard.
- Check the season. Pre-emergent goes down before weeds appear. Post-emergent goes on when weeds are actively growing.
- Plan for follow-up. A single spray rarely clears tough weeds. Most weed killers need a second pass 2 to 4 weeks later for full kill.
How to Apply Weed Killer Safely
- Read the full label before mixing.
- Wear gloves, long sleeves, closed shoes and eye protection.
- Mix at the rate shown. Stronger does not mean better. Higher rates can damage grass roots and fail to kill the weed.
- Spray on a still day. Wind drift kills garden plants and other plants nearby.
- Keep pets and kids off the lawn until the spray has dried, usually a few hours.
- Avoid spraying when rain is forecast within 4 to 6 hours unless the label promises rain resistance.
- For Bow & Arrow specifically, do not water in for several days after spraying.
- Do not mow 2 to 3 days before or after spraying. The leaf needs surface area to absorb the active ingredient.
- Wash hands, gear and sprayer thoroughly after use.
- Store chemical weed killers locked away from kids, pets and food.
For organic gardening setups, hand-pulling, hot water, mulching and boosting lawn density through fertiliser are the main tools. A thick lawn outcompetes most weeds without harsh chemicals. See ALC’s Selective Lawn Weed Killer Turf Control guide for more options.
After You Spray: Lawn Recovery
A healthy lawn keeps new weeds out. Once the existing weed control job is done, focus on density and root depth.
- Feed with a balanced fertiliser once growth resumes. Lawn Play All Rounder is suitable for buffalo, couch, and zoysia.
- Mow at the higher end of the recommended range for your grass type.
- Water deeply, less often, to push grass roots down.
- Top-dress thin areas after the next mow.
- Patch with fresh instant turf rolls (not seed) only after the herbicide withholding period on the label.
For a year-round program that ties weed control, fertilising and aeration together, the Yearly Lawn Care Plan gives you the full schedule by month. For a deeper look at common weed pressure, ALC’s Lawn Weeds Guide walks through ID and control.
Australian Lawn Concepts: Your Partner in Lawn Care
ALC supplies turf and lawn care products to homeowners across Queensland, New South Wales and beyond.
From the farm at Boyland we grow Sir Walter, Sapphire, Wintergreen Couch, IronCutter Elite Bermuda, Nara Native Zoysia, Empire Zoysia and Augusta Zoysia, paired with the herbicides, fertilisers and tools to keep them clean and green.
Need help picking the right weed killer? Browse the full weed killer range or read more lawn care tips to plan your year.
Telephone: 07 5541 7000
Email: customerservice@alcturf.com.au
Or book a Free Prep & Lay Quote through the ALC site.
People Also Ask
These are the questions Aussie lawn owners ask most often about weed control. Quick answers below, then circle back to the sections above for the detail.
1. What Is the Best Weed Killer for Lawns in Australia?
The best weed killer for lawns Australia depends on the weed. For broadleaf weeds in buffalo, couch and kikuyu lawns, Bow & Arrow is the standard pick. For nutgrass and Mullumbimby couch, Tempra. For Winter Grass and Summer Grass before they sprout, OxStar pre emergent. Match the product to the weed for the best result.
2. Is Bow and Arrow Safe on Buffalo Grass?
Bow & Arrow is safe on modern soft-leaf buffalo lawns including Sir Walter and Sapphire when used at the label rate of 50 mL in 5 L water per 100 m². Older common buffalo strains can react to MCPA, so test a small patch first if you are unsure. Always spray when the lawn is actively growing, never on stressed or dormant turf.
3. When Should I Apply Pre Emergent Weed Killer in Australia?
Apply pre emergent herbicide before the weed seeds germinate. For Winter Grass, that means soil temps consistently around 10°C, typically late summer to early autumn (February to April), at 4 kg per 100 m² of OxStar. For Summer Grass and Crowsfoot Grass, apply late winter to early spring (August to October) at 3 kg per 100 m². OxStar feeds the lawn at the same time, doubling as a fertiliser.
4. How Long Does Lawn Weed Killer Take to Work?
For Bow & Arrow, you’ll see leaf curling within 3 to 4 days, with full kill at 7 to 14 days. Tempra typically shows yellowing within 7 to 10 days on nutgrass, with full kill at 2 to 4 weeks. Pre emergent products like OxStar do not show visible action. They stop weed seeds from germinating in the first place, so the proof is the weeds you do not see.
5. Can I Use Weed Killer on Couch and Zoysia Lawns?
Yes. Bow & Arrow, Tempra and OxStar are all safe on Wintergreen Couch, Common Couch, Blue Couch, Saltwater Couch, Empire Zoysia, Nara Native Zoysia and Augusta Zoysia at label rates. Santa Ana couch is the one exception. OxStar is not safe on it. Spray when the lawn is actively growing, the soil is moist, and no rain is forecast for at least four hours.
6. Do I Have to Water in Bow & Arrow After Spraying?
No. The Bow & Arrow label specifically states that watering-in or rainfall within a few days of application is not recommended, since it washes the active off the leaf before it can be absorbed. Plan your spray for a dry weather window. Wait at least three to four days before watering or mowing the treated area for full effect.
7. What’s the Difference Between OxStar 20 kg and OxStar 8 kg?
The 20 kg bag covers 500 m² and is best for medium to large lawns. The 8 kg bag covers 200 m² and is the right call for smaller suburban yards. Both contain the same Oxadiazon active ingredient and the same N-P-K fertiliser blend, so the only difference is the pack size for your lawn area.
8. Can I Use Weed Killer on a Newly Laid Lawn?
Wait until your new turf is firmly rooted, usually 6 to 8 weeks after install, before applying any selective herbicide. Pre emergent OxStar is best held off until the lawn has been mowed two or three times. Spraying too early stresses young roots and can pull the rolls out of place. See ALC’s Yearly Lawn Care Plan for safe windows.
9. What’s the Best Weed Killer for Bindii?
Bow & Arrow is the standard pick for bindii (Soliva sessilis), since the MCPA, Clopyralid and Diflufenican blend kills the rosette before it sets prickly seed. Spray in May to August when the bindii is actively growing and before flowers form. A second pass 2 to 4 weeks later cleans up any survivors.