Understanding application rates per 100m²
At New Zealand Lawn Addicts, we use an application rate based on mL (millilitres) per 100m², which is the same system used throughout the professional lawn care industry. This approach ensures the correct amount of product is applied to the lawn and helps prevent accidental over-application, which can burn your lawn. Over-application can easily occur when using the confusing mL per litre method commonly seen on big box store products.
Many professional products do not have the large margin for error that cheaper retail products are designed to tolerate, so accuracy matters.
Why mL per litre often causes problems
The mL per litre method is easy to misuse because the final amount of product applied depends entirely on how much water you spray.
For example, if the label rate is 60 mL per 100m² and you mix 12 mL per litre, that only works if you apply exactly 5 litres of water over 100m²:
12 mL × 5 L = 60 mL.
However, if you end up spraying 8 litres over that same 100m² area, you would apply:
12 mL × 8 L = 96 mL.
That is 36 mL more than the label rate, or 50 percent too much product.
This kind of mistake is common with consumer-grade products, but when using professional lawn products these differences can lead to serious over-application.
Why NZLA uses rates per 100m²
Applying products per 100m² is the most reliable method because the product rate is tied directly to the size of the area being treated. Water then becomes nothing more than the carrier used to spread the product across the lawn.
Whether you use 4 litres, 6 litres, or 8 litres of water to cover 100m², the product rate remains exactly the same.
This removes the risk of accidentally increasing the dose and ensures the correct amount of active ingredient reaches the lawn.
How to apply NZLA products properly
Step 1: Calculate your lawn size
Start by measuring your lawn accurately. You can do this manually or by using the lawn measuring tool in the New Zealand Lawn Addicts App.
Step 2: Test your walking pace
Fill your sprayer with water only and walk your lawn at a normal pace while spraying. Measure how much water you used to cover the area.
For example, if your lawn is 100m² and you used 6 litres of water, that becomes your baseline. This process is what people refer to as calibrating a sprayer. In simple terms, you are working out how much water you apply while walking and spraying your lawn at a normal pace.
Step 3: Calculate the product dosage
Once you know how much water you normally use, you can calculate the correct amount of product.
For this example we will use NZLA Grub+, which has an application rate of 15 mL per 100m².
If your lawn is 100m², you would simply add 15 mL of product to however much water your sprayer uses to cover that area.
Example
In this situation, a customer has 350m² of lawn and used 16 litres of water to cover the area during calibration.
If the product application rate is 15 mL per 100m², the product calculation for 350m² is:
15 mL × 3.5 = 52.5 mL.
This means that whatever amount of water was used to spray the 350m² lawn during calibration, in this case 16 litres, you simply add 52.5 mL of product to that tank. Doing this ensures the correct rate of 15 mL per 100m² is applied.
The New Zealand Lawn Addicts App also includes a product application helper that automatically calculates the correct amount for each product based on the lawns you have saved in the app.
Step 4: Understand water volumes
The key point is that water is simply the delivery mechanism. Whether you use 4, 5, or 7 litres per 100m², the amount of product applied to that area stays the same.
That said, product labels often specify a minimum water volume. This is important to follow, especially for products that need to remain on the leaf surface, as excessive water can wash the product off the plant.
In practice, most people spraying at a normal walking pace will fall within the recommended water volumes.
Still confused?
Check out the NZLA Facebook group where more than 20,000 customers share advice, results, and real-world experience. There is a huge amount of practical knowledge in the group.
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