Winter weeds are taking over your lawn. Here's what actually works.

If your lawn is looking worse than it did a month ago and you can see patches of lighter green growth, fine-textured clumps, or low-spreading weeds creeping through the turf, you are dealing with one of two problems. They look similar from a distance. They need completely different treatment. Most people buy the wrong product, get no result, and assume their lawn is beyond help. It is not. You just need to know what you are actually dealing with.

Two types of winter weeds. Two completely different fixes.

Winter lawn weeds fall into 2 categories: grassy weeds and broadleaf weeds. The distinction matters because no single product kills both, and the most common mistake Australian homeowners make is reaching for a broadleaf herbicide to kill a grassy weed. It will not work.

Winter grass (Poa annua) is the grassy weed. It is a fine-textured, light green annual that germinates when soil temperatures drop below around 12 degrees, typically from March onwards in southern Australia. It forms clumps that stand out clearly against warm-season grasses like couch, kikuyu, and buffalo. By early spring it produces thousands of seeds before dying off in the heat, and those seeds stay viable in the soil for years, ready to germinate again next autumn.

Broadleaf weeds are the other category. Bindii, clover, capeweed, plantain, cudweed, and creeping oxalis all fall here. These have wide, flat leaves and spread low across the lawn. They thrive in winter because your warm-season grass has slowed down and left gaps for them to exploit.

What to do right now if weeds are already up

If you have broadleaf weeds, bindii, clover, capeweed and similar, Bow and Arrow is the product to reach for. It is a selective post-emergent herbicide with 3 active ingredients that controls broadleaf weeds across most common Australian lawn types. It works more slowly than some other options but delivers a more complete result with less chance of the weed recovering from its root system. Apply it while the weeds are actively growing.

If it is already spring and the weeds have set seed, spray anyway. It will not undo seed that has already hardened, but it stops that seed being added to for another year. Mature weeds take longer to die and may need a second pass 4 to 6 weeks later.

A few turf-safety notes from the label that matter. Bow and Arrow can cause transient discolouration on kikuyu, carpet grass, and Queensland blue couch. It passes, but do not be alarmed by it. Some buffalo varieties, ST85 in particular, react more strongly, so test a small area first before you spray the whole lawn. Do not use it on bent grass. From September onward, spray early morning or late afternoon, since MCPA can cause discolouration in heat or on stressed turf. We cover the full application detail in our guide to controlling bindii.

If you have winter grass, this is where it gets more complicated. Post-emergent options that selectively kill Poa annua do exist, but which product is safe depends entirely on your grass type. The compatibility matrix is specific enough that recommending a single product here would be the wrong approach. If winter grass is already up in your lawn and you want to treat it this season, reach out to us directly. Tell us your grass type and we will point you to the right product for your specific situation.

Email us at info@turfandsurf.com.au and we will guide you through it.

The most common mistake: using Bow and Arrow on winter grass

Bow and Arrow is one of the best broadleaf herbicides available in Australia. But winter grass is not a broadleaf weed. It is a grassy weed. Applying Bow and Arrow to Poa annua will have no effect. If you have done this and seen no result, this is why. The product worked exactly as it was designed to. It just was not designed for that problem.

Stop grassy weeds before they start

The most effective way to deal with grassy weeds is to prevent them germinating in the first place. This is where Spartan comes in. Spartan is a pre-emergent herbicide with the active ingredient prodiamine at 480g per litre. Applied and watered in, it forms a barrier in the top layer of soil that blocks root development in germinating seedlings. It is safe on established turf including zoysia, kikuyu, couch, and buffalo, and provides up to 6 months of protection at the higher rate.

There are 2 windows a year, not one.

April, before winter grass germinates as soil temperatures drop. This is the window most people know about.

September, before summer grass and crab grass germinate as soil temperatures rise. This one gets missed, and it is the reason so many lawns that beat winter grass still end up full of summer grass by January.

The rate is 10 to 30ml per 100m2 in 2 to 5L of water. Use 30ml for high weed pressure or the full 6 months of residual, and 10ml for standard situations at around 4 months. Do not exceed the label rate. Water in thoroughly after application to activate the barrier, avoid mowing for 2 days either side, and do not apply to stressed or water-deficient turf.

The timing is non-negotiable. Pre-emergent herbicides must go down before the seeds germinate. If the weeds are already visible, Spartan cannot kill them. It can only prevent the next generation.

Why weeds keep coming back: the real problem underneath

Herbicides fix what is visible. They do not fix why the weeds got in. Winter weeds take hold in lawns that have thin coverage, depleted soil, and poor water penetration, conditions that create the exact gaps weeds need to establish. A dense, healthy lawn with an active root zone and soil that holds moisture is the single best long-term defence against weed invasion.

This is where the Turf & Surf soil program comes in. Soak opens up hydrophobic soil so water and nutrients actually reach the root zone. Vital stimulates root development to build the dense coverage that closes gaps. Base conditions the soil biology so the whole system functions the way it should, at 120ml per 100m2 watered in immediately after application. Through winter, Vivid at the reduced 100ml per 100m2 rate keeps colour in the leaf layer, applied to the leaf and left for 2 hours before watering in.

Herbicides and lawn health work together. You remove the weeds, then you build the lawn that stops them coming back.

Complete the program

If you want to understand the full seasonal approach to a lawn that stays dense, healthy, and weed-resistant all year, the Turf & Surf 5-step program covers the complete picture. Every product, every layer, every month. New to it? The Starter Pack covers Soak, Vital and Surge for $150.

Frequently asked questions

Will Bow and Arrow kill winter grass?
No. Bow and Arrow is a broadleaf herbicide. Winter grass (Poa annua) is a grassy weed. The product will have no effect on it. You need a selective post-emergent herbicide appropriate for your grass type, or a pre-emergent like Spartan applied in the April window.

Winter grass is already up. Can I still use Spartan?
Spartan is a pre-emergent. It prevents seeds from germinating and will not kill weeds already visible. Manage what is there now, then apply Spartan in April before soil temperatures drop. If it is currently spring, the September window is open for summer grass and crab grass, which is a different germination flush worth stopping.

What rate should I use for Spartan?
10 to 30ml per 100m2 in 2 to 5L of water. Use 30ml for high weed pressure or the full 6 months of protection, 10ml for standard situations. Do not exceed 30ml per 100m2.

Which post-emergent herbicide kills winter grass in my lawn?
It depends on your grass type. Options exist but compatibility varies, and the wrong product on the wrong grass type causes damage. Email us at info@turfandsurf.com.au with your grass type and we will guide you to the right product.

Is Bow and Arrow safe on my buffalo lawn?
In most cases yes, but some buffalo varieties, ST85 in particular, can react more strongly to it. The label advises testing a small area first before treating the whole lawn. On kikuyu, carpet grass, and Queensland blue couch you may see transient discolouration that passes on its own.

My lawn is thin and full of weeds. Where do I start?
Treat the weeds first with the appropriate herbicide, then build the lawn underneath so they cannot come back. A thin, depleted lawn will always be vulnerable. The Starter Pack is the right starting point for most Australian lawns that need the soil foundation rebuilt.

How do I know if I have winter grass or a broadleaf weed?
Winter grass looks like grass, fine-textured, light green, growing in clumps. Broadleaf weeds have wide, flat leaves and a low spreading growth habit. If you are unsure, send us a photo at info@turfandsurf.com.au and we will identify it for you.