When to Apply Weed Control to Your Lawn

Weeds are one of the biggest frustrations for Australian homeowners. One minute your lawn looks healthy, the next it’s covered in bindii, clover, crabgrass, or broadleaf weeds competing with your grass for water and nutrients.



Knowing when to apply weed control is just as important as knowing what to apply. Treating weeds at the wrong time can waste money, damage your lawn, or make the problem worse.

This guide explains the best times of year to apply weed control, how weather affects results, and how to keep your lawn weed-free long term.

Why Timing Matters With Weed Control

Applying weed killer at the wrong time is one of the most common mistakes homeowners make.

Correct timing:

• Improves weed kill rates
• Reduces repeat treatments
• Protects healthy grass
• Saves money on unnecessary products

Weeds are easiest to control when they are actively growing. Applying herbicide when weeds are dormant, stressed, or about to seed is far less effective.

The Best Time of Year to Apply Weed Control

Spring: The Most Important Time for Weed Control

Spring is the best overall time to control weeds in Australian lawns.

Why spring works best:

• Weeds begin actively growing
• Soil temperatures rise
• Grass starts recovering from winter
• Weeds are weaker before seeding

Spring treatments help stop weeds before they spread through the lawn during summer.

Best weeds to target in spring:

• Bindii
• Clover
• Winter grass (Poa annua)
• Broadleaf weeds

Applying weed control early in spring gives your lawn a strong head start.

Summer: Spot Treatments Only

Summer weed control should be approached carefully, especially in hot Queensland conditions.

During extreme heat:

• Lawns are already under stress
• Herbicides can burn grass
• Effectiveness is reduced

If weed control is needed in summer:

• Spot spray only
• Apply during cooler mornings
• Avoid days over 30°C
• Ensure lawn is well watered beforehand

Summer is best used for maintenance, not large-scale weed removal.

Autumn: Second-Best Time for Weed Control

Autumn is another excellent time to apply weed control.

Why autumn is effective:

• Weeds are still actively growing
• Cooler temperatures reduce lawn stress
• Less evaporation improves absorption
• Prepares lawn for winter

Autumn weed control reduces weed pressure heading into winter and spring.

Winter: Generally Not Recommended

In most parts of Australia, winter is not ideal for weed control.

Reasons winter treatments are less effective:

• Weed growth slows or stops
• Herbicides don’t absorb properly
• Cold soil limits results

The exception is mild climates where weeds remain active year-round, but even then results are slower.

Pre-Emergent vs Post-Emergent Weed Control

Understanding the difference helps you choose the right timing.

Pre-emergent weed control

• Prevents weed seeds from germinating
• Applied before weeds appear
• Most effective in early spring or early autumn

Pre-emergents are great for stopping recurring weeds like crabgrass.

Post-emergent weed control

• Kills weeds that are already visible
• Best applied when weeds are young and growing
• Used throughout spring and autumn

Most homeowners rely on post-emergent treatments.

Best Weather Conditions for Applying Weed Control

Weather plays a huge role in success.

Ideal conditions:

• Mild temperatures (15–25°C)
• No rain forecast for 24 hours
• Light breeze or calm conditions
• Lawn not under drought stress

Avoid applying weed control when:

• Heavy rain is expected
• Temperatures exceed 30°C
• Lawn is dry or stressed
• Frost is likely overnight

Poor conditions can wash chemicals away or damage your grass.

How Lawn Type Affects Weed Control Timing

Different grasses respond differently to weed treatments.

Buffalo lawns

• More sensitive to chemicals
• Require buffalo-safe herbicides
• Best treated in mild spring or autumn conditions

Couch lawns

• More tolerant of weed control
• Can handle a wider range of treatments
• Respond well in spring

Kikuyu lawns

• Fast-growing and aggressive
• Responds best to early treatment
• Needs careful control to avoid damage

Always match the product to your lawn type.

How Often Should You Apply Weed Control?

This depends on weed pressure and lawn health.

General guideline:

• Broadscale treatment: 1–2 times per year
• Spot spraying: as needed
• Pre-emergent treatments: once per season

Over-applying weed killer can weaken grass and create more bare patches for weeds to return.

Common Weed Control Mistakes to Avoid

Many weed problems are caused by simple mistakes.

Avoid:

• Spraying during heatwaves
• Mowing immediately before or after spraying
• Using incorrect herbicides
• Over-applying product
• Ignoring underlying lawn health issues

Weeds thrive in weak lawns. Killing weeds without fixing the cause often leads to repeat infestations.

How Lawn Health Impacts Weed Growth

Healthy lawns naturally resist weeds.

Key factors:

• Proper mowing height
• Regular fertilising
• Consistent watering
• Good soil structure

Thick, healthy grass shades the soil, making it harder for weeds to establish.

Should You DIY or Hire a Professional?

DIY weed control can work for small issues, but professional services offer advantages.

Professional weed control:

• Correct product selection
• Safe application rates
• Lawn-specific treatment plans
• Long-term prevention strategies

At Order of the Lawn, we don’t just treat weeds — we improve overall lawn health to stop them coming back.

When to Call in the Experts

Consider professional help if:

• Weeds keep returning
• Large areas are affected
• Lawn has mixed grass types
• You’re unsure which product to use
• You want long-lasting results

Incorrect treatments can cost more to fix later.

Keep Your Lawn Weed-Free Year-Round

The best weed control strategy combines timing, consistency, and lawn care.

• Treat weeds in spring and autumn
• Maintain proper mowing height
• Fertilise seasonally
• Improve soil health
• Spot-treat early

This approach reduces the need for harsh chemicals over time.