How to Get Rid of Winter Grass from Your Lawn: Complete Guide

Winter grass (Poa annua) is one of the most frustrating lawn weeds for Australian homeowners. Often called annual bluegrass, annual grass, or goose grass among other names, it sneaks into your lawn in the cooler months and spreads rapidly, creating unsightly light green patches that stand out against your couch, buffalo, or kikuyu lawn.

In this guide, we’ll explain exactly what winter grass is, how to get rid of it, and—most importantly—how to prevent it from returning next year.

What Is Winter Grass (Poa annua)?

Winter grass, or Poa annua, is an annual cool-season weed that thrives when your lawn slows down in autumn and winter. It is highly adaptable, growing in a wide range of soil types and conditions.

Key Characteristics:

• Light green, soft, flat leaves with boat-shaped or blunted tips
• Clumpy, tufted growth habit that forms dense patches
• Distinctive panicle-like seed heads that resemble tiny Christmas trees
• Grows up to 30cm tall, though shorter in well-maintained lawns
• Prefers shaded, damp, or compacted areas
• Prolific seed producer—one plant can produce thousands of seeds
• Shallow fibrous roots; does not spread via stolons or runners

Lifecycle of Winter Grass

Winter grass germinates in autumn or early winter, grows through the cooler months, and sets seed in late spring, ensuring a new generation for the following year. In cool areas, it can grow almost year-round. Even though it dies off in spring, the seeds it drops mean it will return stronger if left untreated.

Why Winter Grass Is a Problem

Winter grass might look harmless at first, but it can quickly ruin the uniformity and health of your lawn. Here’s why it’s a common nuisance:

1. Visual Disruption – Breaks the even colour and texture of your lawn
2. Rapid Spread – Thousands of seeds per plant create large infestations quickly
3. Weakens Turf – Competes with your grass for water, nutrients, and sunlight
4. Bare Patches – Dies off in spring, leaving unsightly brown spots
5. Difficult to Control – Herbicides are less effective after seeds have set

For lawns you’ve worked hard to maintain, winter grass can undo months of effort if not addressed early.

How to Get Rid of Winter Grass from Your Lawn?

There are two main approaches to controlling winter grass: post-emergent (treating what’s already there) and pre-emergent (preventing seeds from germinating).

1. Post-Emergent Control – Killing Existing Winter Grass

If winter grass is already growing in your lawn:

• Hand-Pulling: For small infestations, use a hand fork or hoe to lift plants from their shallow roots. Do not compost removed plants—seeds will germinate again.
• Selective Herbicides: Use winter grass killers that target Poa annua roots without harming your turf, such as Winter Grass Killer or OxaFert. Apply early in the lifecycle, before seed heads appear.

Tips for effective post-emergent control:

• Check flower beds, borders, and cracks in paths or patios for additional plants
• Expect repeated treatments over several years to fully control infestations
• Repair bare spots with a top dressing or products like Scotts Lawn Builder™ Patch Magic

2. Pre-Emergent Control – Stopping Winter Grass Before It Starts

Pre-emergent herbicides prevent winter grass seeds from germinating. For best results:

• Apply in late summer or early autumn, before seeds begin to sprout
• Rotate products to prevent winter grass from developing tolerance (similar to antibiotic resistance)
• Can be applied at the same time as fertiliser, but do not mix in the same sprayer unless the label allows

Recommended pre-emergent options include:

• OxaFert – fertiliser + pre-emergent combination
• Oxafert Plus – larger bag with added insecticide
• Barricade Pre-Emergent Herbicide – liquid option

A 3kg bag of Oxafert treats up to 100m².

Natural and Cultural Control Methods

Environmentally friendly practices can complement chemical treatments and strengthen your lawn:

• Promote Dense Turf: Feed, water, and mow regularly to encourage healthy lawn growth that outcompetes weeds.
• Dethatching & Aeration: Disrupts winter grass growth and improves soil health
• Mowing: Can sometimes control seedlings before germination, but beware of scalping turf.
• Sunlight & Shade Management: Reduce shade to weaken winter grass; it struggles more than other grasses when soil dries out.
• Watering: Avoid watering in dry spells; shallow roots make winter grass less drought-tolerant.
• Avoid Lime: Winter grass prefers alkaline soils, so do not add lime.

Preventing Winter Grass From Returning

The best strategy is a combination of healthy lawn practices and timely herbicide applications:

• Maintain a thick, vigorous lawn to naturally outcompete weeds.
• Apply pre-emergent herbicides before seeds germinate.
• Use post-emergent herbicides on young plants before they set seed.
• Hand-pull isolated clumps where practical.
• Repair bare patches promptly to prevent new infestations.
• By staying vigilant and consistent, you can break the lifecycle of winter grass and enjoy a uniform, healthy lawn year-round.

Key Takeaways

• Winter grass (Poa annua) is annual, prolific, and highly visible in Australian lawns.
• It can spread rapidly and leave bare patches if untreated.
• Early control and prevention is essential.
• Use a combination of:

Pre-emergent herbicides in late summer/early autumn

Selective post-emergent herbicides for existing weeds

Cultural and natural methods to strengthen your lawn

With the right approach, you can stop winter grass from taking over and keep your lawn healthy, green, and uniform all year.

If you're interested in learning more about how to treat other types of lawn weeds, we have plenty more advice on that! Identifying lawn weeds can sometimes be a bit tricky, but we've got you covered. Head to our how to's, news & updates, or product info pages to learn more about different types of weeds like Bindii, Nut Grass, or Paspalum.