Key Takeaways
- To kill weeds without killing grass, choose a selective lawn weed killer designed for weeds growing in turfgrass.
- Non-selective weed killers can damage or kill grass, so they are better suited to gravel, driveways, fence lines and other non-lawn areas.
- PAR III is suitable for broadleaf weeds growing in lawns, while Roundup Transorb is better suited to broader vegetation control where grass does not need to remain.
- Always identify where the weeds are growing before choosing a product.
- Apply weed control products in suitable weather conditions and always follow the product label.
- Keeping your lawn thick and healthy can help reduce future weed growth.
Weeds growing through the lawn can be frustrating, especially when you want to remove them without damaging the grass around them. The key is choosing the right type of weed control product for the area you are treating.
Some weed killers are designed for use within lawns, while others are designed to clear unwanted vegetation from areas such as gravel, driveways, fence lines or rough ground. Choosing the wrong type can lead to damaged grass or poor results.
In this guide, we explain how to kill weeds without killing grass, how to choose between lawn and non-lawn weed control products, and when products like PAR III and Roundup Transorb may be suitable for different areas of your property.
Quick Navigation:
- Why Some Weed Killers Also Kill Grass
- What Type of Weed Killer Won’t Kill Grass?
- Selective vs Non-Selective Weed Killers
- Common Lawn Weeds Found in Grass
- How to Kill Weeds Without Damaging Your Lawn
- When Should You Treat Lawn Weeds?
- When Not to Use Roundup on Grass
- How to Stop Weeds Coming Back
- FAQs
Why Some Weed Killers Also Kill Grass
Not all weed killers are designed for the same purpose. Some are made for use in lawns, while others are designed to clear a wider range of unwanted vegetation.
If you use a non-selective weed killer on your lawn, it may not only affect the weeds. It can also damage or kill the surrounding grass. This is why it is important to check whether a product is suitable for lawn use before applying it to any grassed area.
For lawn weeds, choose a product that is specifically labelled for use on grass and always follow the application guidance carefully.
Avoid this mistake: Do not use a total vegetation killer on your lawn unless you are intentionally trying to clear the grass as well.
What Type of Weed Killer Won’t Kill Grass?
If you want to kill weeds without killing grass, you will usually need a selective lawn weed killer. These products are designed to target certain types of weeds while leaving the surrounding grass intact when used correctly.
They are commonly used on visible lawn weeds such as dandelions, clover, plantain, thistle and ground ivy. This makes them useful when the weeds are growing through the grass and the goal is to keep the lawn in place.
The most important step is to check the product label before applying anything to your lawn. This helps confirm where the product can be used, which weeds it is designed for and how it should be applied.
Selective vs Non-Selective Weed Killers
The easiest way to choose the right weed killer is to look at where the weeds are growing.
If the weeds are growing within your lawn and you want to keep the grass, choose a lawn-suitable product. If the weeds are growing in gravel, driveways, paths, fence lines or rough ground where you do not want vegetation to remain, a non-selective weed killer may be more suitable.
| Weed Control Type | What does it do? | Best used for |
| Selective lawn weed killer | Targets certain weeds while helping keep grass intact when used as directed | Dandelions, clover, plantain and other broadleaf weeds in lawns |
| Non-selective weed killer | Controls a wider range of unwanted vegetation, including grass | Driveways, gravel, paths, fence lines and non-lawn areas |
For Canadian Lawn Co. products, PAR III is the more suitable option for weeds growing within lawns and maintained turf areas. Roundup Transorb is better suited to broader vegetation control in non-lawn areas where grass and other plants do not need to remain. You can also get both as a bundle to treat your whole property.
Common Lawn Weeds Found in Grass
Many common lawn weeds look noticeably different from the surrounding grass. Some have wider leaves, visible flowers, spreading stems or low-growing patches that stand out across the lawn.
Common weeds found in Canadian lawns include:
- Dandelions
- Clover
- Plantain
- Thistle
- Ground ivy / Creeping Charlie
- Chickweed
- Black medic
Before applying any treatment, take a moment to identify the weed and check the product label to make sure it is suitable for the area you are treating.
How to Kill Weeds Without Damaging Your Lawn
Once you know the weeds are growing within the lawn, the next step is to treat them carefully. The aim is to control the weeds without stressing the grass or affecting nearby plants.
A simple approach is:
- Identify the weed and the area it is growing in
Check whether the weeds are in the lawn itself or in a non-lawn area such as gravel, paths or fence lines. - Choose a lawn-suitable product
Use a product that is labelled for the type of lawn area and weeds you want to treat. - Read the product label before applying
Check where the product can be used, how it should be applied, what conditions to avoid and whether there are any safety steps to follow. - Apply in suitable weather
Avoid strong wind, extreme heat or heavy rain. Calm, dry conditions are usually better for controlled application. - Give the treatment time to work
Weeds may not disappear immediately. Results can vary depending on the weed type, weather and how established the weeds are. - Support the lawn afterwards
Keep the grass healthy by mowing at a suitable height, repairing bare patches and encouraging thicker growth over time
When Should You Treat Lawn Weeds?
Lawn weed control usually works best when weeds are actively growing and the lawn is not under too much stress. In Canada, this often makes spring and fall useful times to treat common lawn weeds.
Spring can be a good time to deal with weeds as the lawn starts growing again and new weed growth becomes easier to spot. Fall can also be useful for tackling weeds before the lawn slows down for winter.
Try to avoid applying weed control products during extreme heat, drought stress, strong wind or shortly before heavy rain unless the product label says otherwise. Suitable conditions can help the treatment work more effectively while reducing the risk of drift or damage to nearby plants.
| Best Conditions for Weed Control Weeds are actively growing Lawn is not heavily stressed Weather is calm No heavy rain is expected Product label confirms conditions are suitable |
Where Roundup Transorb Fits
While PAR III is a selective weed killer, more suited to weeds growing within lawns and maintained grass areas where you don’t wish to damage or harm the surrounding area. Roundup Transorb is better suited to non-lawn weed control like gravel, driveways and fence lines where you want to clear all unwanted vegetation rather than protecting grass.
For many properties, both types of weed control can be useful. The important thing is to match the product to the area you are treating: lawn weeds need a lawn-suitable approach, while unwanted growth outside the lawn may need broader vegetation control.
How to Stop Weeds Coming Back
Killing existing weeds is only part of the process. If the lawn is thin, patchy or stressed, weeds may return over time.
A thicker, healthier lawn gives weeds less room to grow and can make future weed control easier. After treating weeds, it is worth looking at the overall condition of the lawn and making small improvements where needed.
To help reduce future weed growth:
- Overseed thin or bare areas
- Avoid mowing the grass too short
- Water deeply rather than lightly
- Improve compacted soil where possible
- Repair bare patches after weeds die back
- Treat weeds before they can spread
- Keep up with seasonal lawn care
Long-term weed control works best when suitable treatment is combined with regular lawn maintenance.
FAQs
What kills weeds but not grass?
A lawn-suitable selective weed killer is usually the best option when weeds are growing within grass. These products are designed to target certain weeds while helping to keep the surrounding lawn intact when used correctly and according to the product label.
Will Roundup kill grass?
Roundup-style non-selective weed killers can damage or kill grass. They are generally better suited to non-lawn areas where you want to clear unwanted vegetation, such as gravel, driveways, paths, fence lines and rough ground.
What is the best weed killer for weeds in grass?
The best option depends on the type of weeds in your lawn and the area you are treating. For common weeds growing within lawns and maintained grass areas, a product such as PAR III may be more suitable than a non-selective weed killer.
Can I spray weeds without damaging my lawn?
Yes, but you need to use the right product and apply it carefully. Identify the weed, choose a product suitable for lawn use, read the label, avoid unsuitable weather and do not apply more than recommended.
When is the best time to treat lawn weeds?
Lawn weed control often works best when weeds are actively growing and the lawn is not under heavy stress. Spring and fall are often useful times in Canada, but you should always check the product label and avoid poor weather conditions such as strong wind, extreme heat or heavy rain.
How do I stop weeds growing back in my lawn?
The best way to reduce future weed growth is to keep the lawn thick and healthy. Overseeding thin patches, mowing at a suitable height, repairing bare areas and treating weeds early can all help reduce the chance of weeds returning.
Final Thoughts
Killing weeds without killing grass comes down to choosing the right product for the right area. If weeds are growing within the lawn, use a product that is suitable for grassed areas and follow the label carefully. If weeds are growing in gravel, driveways, paths or fence lines, a broader vegetation control product may be more appropriate.
For lawn weeds, PAR III is the more suitable option from Canadian Lawn Co. For non-lawn areas where unwanted vegetation needs clearing, Roundup Transorb may be a better fit.