The Concise Lawn Fertiliser Guide

We first suggest doing a pH Soil Test to test your lawn’s soil quality.

It’s important to understand the quality of your soil so that you can make better-informed decisions when it comes to choosing the right fertiliser.

A pH value of over 7 indicates you have alkaline soil and your turf needs phosphorus (P) and potentially iron (Fe). 

A pH level that falls below 7 indicates your soil is acidic and needs potassium (K) and potentially magnesium (Mg).

By understanding your soil quality and pH results, you’ll be able to choose the right fertiliser for your lawn according to the nutrients required.

Realistically, the closer you can get your soil to that magic 7 mark, the better the soil quality meaning a better plant and a better lawn to enjoy. A good place to start when looking at improving your lawn is a soil test.

There are a few ways to test your soil pH.

The first is a simple test kit available at your Local Garden Centre. Soil pH kits are a very simple, cheap and effective way to get an idea of what you are dealing with. Soil pH kits come with easy-to-follow instructions that provide you a result that can be compared to the supplied colour chart, giving you an idea as to what pH your soil is.

When using these soil pH test kits, it is always an advantage to take the soil from your lawn around 100mm deep in several spots and mix them together then test. Why? This will give you an average across your lawn.

The biggest mistake people make is testing only one spot of their lawn, how can you be sure that where you tested is the same as the other side of the yard?

Soil tests aren’t that expensive. For a scientific look at your lawn, you can expect to pay around $150 and upwards depending on the data you require. Collect your own lawn soil sample by randomly pulling 10 to 12 individual soil samples from your lawn to a depth of about 10cm. Make sure there is no vegetation or excessive root mass in the soil sample.

Mix your lawn’s soil samples and place about a cup of the mix into a plastic bag with your name and details attached and ask your Local Garden Centre to have it tested. The soil test results will provide important information that will help determine what type of lawn fertiliser you should use and how often.

Each lawn fertiliser comes with three macro-nutrients, Nitrogen, Phosphorus and Potassium. 

Depending on the type of lawn and soil quality, it will require a fertiliser that has a certain blend of these three nutrients to thrive. 

 

Nitrogen (N)

• Nitrogen is usually the highest percentage found in fertiliser
• If your grass is beginning to look yellow in some areas, it’s likely to be Nitrogen-deficient
• Nitrogen has properties that improve the health of grass leaves and therefore helps your lawn appear greener, thicker and fresher

Potassium (K)

• Potassium is required to help your lawn’s overall functions
• It is the key nutrient to strengthening cell walls and therefore makes your lawn more durable so to withstand extreme weather conditions.

Phosphorus (P)

• Phosphorus is used for the healthy growth of your lawn’s roots
• Only a small percentage is usually required

The ratio of Nitrogen, Phosphorus, and Potassium plays a part in determining the right fertiliser for your lawn. 

As mentioned above, conducting a soil test will point you in the right direction in choosing the right fertiliser and NPK ratio for your lawn.

Before fertilising, and while waiting for your soil test to come back, aerate, and rake your lawn to remove leaves and other debris.

If you decide to mow, allow at least two days before fertilising.

Once you fertilise your lawn – wait at least a week before mowing and when you mow for the first time leave the catcher off (this is so the fertiliser remains on the lawn).

Always select a fertiliser that suits your type of lawn and the time of year when you are fertilising.

Best fertiliser results occur when feeding your lawn at least three times a year:

• early spring
• early summer
• mid to late autumn

If you decide to only feed your lawn once – this is best done during late spring or early summer.

Always read the fertiliser’s directions before applying to your lawn and use a spreader (handheld or wheeled) to ensure even coverage.

Again, the best fertilizer for your lawn is one that contains the nutrients your soil needs that’s why doing a soil test can be very helpful.

Fertilisers are most often sold by a numbering system that can represent several nutrient ratios such as nitrogen (N), phosphorus (P), potassium (K), sulphur (S), Iron (Fe) and manganese (Mn).

Before applying any fertiliser be sure to find out from your Local Garden Centre what sort of grass you have and if your soil is lacking in nutrients, so you purchase the correct type of fertiliser.

Liquid Lawn Fertiliser

Liquid fertilisers have the advantage of being able to be applied to both the ground or to the lawn foliage itself, also called foliar application. 

Application of liquid fertiliser through the ground will result in the roots absorbing the nutrients whereas application to the plant allows the plant to absorb the fertilisers through the leaves and have the nutrients more readily available for immediate use. 

Foliar application can allow you to make mid-season corrections to add vital nutrients to your lawn if it didn’t get the correct mixture at the beginning of the season and needs a boost.

Another main benefit of a liquid lawn fertiliser is that it can be easily administered to the largest of lawns in a liquid form and absorbed, not only by the lawn foliage itself, but also by the surrounding soil.

This is of great value to lawn care and while liquid fertiliser is commonly more expensive it can be more effective!

Again, the best fertiliser for your lawn is one that contains the nutrients your soil needs.

One of the advantages of using a liquid lawn fertilizer is that you can easily mix in any other nutrients your lawn and soil needs.

Whether you mix concentrate in a litre sprayer (the less expensive option), or purchase a pre-mixed bottle that attaches to your garden hose, lawn liquid fertiliser is more versatile than granular because you can apply it to the ground or the leaf foliage.

Key features of liquid fertiliser:

• Uniform application
• Quick leaf foliage uptake when green-up is needed
• Seasonal application variances available
• Can blend with other liquid products
• Easy to apply

For a good selection of liquid fertilisers have a look at our partners at LawnPride

Slow Release Lawn Granular Fertiliser

Granular lawn fertilisers are dry fertilisers that are made into a pellet form, often blended to get the desired ratio of nutrients needed for your lawn.

Using a granular fertiliser method means you can control the exact amount of Nitrogen, Phosphorus, and Potassium that needs to be added to your lawn.

Most lawns respond well to a slow release granular fertiliser, which can be found at any Local Garden Centre or at our partners Lawn Pride, and they feed the lawn for up to three months.

Using a slow release fertiliser on your lawn once, for example during autumn before the ground becomes too cold, means your lawn will cope through a tough, cold winter.

Application of a slow-release lawn fertiliser should occur during:

• Late March or early April (when the weather is still warm)
• During spring (when the ground has warmed-up)

Key features of slow-release lawn fertilisers:

• The nutrients slowly, continuously release
• All the fertiliser’s nutrients are utilised following watering-in
• Use of low application rates (saves money)
• There is only a need to apply three times during the year (twice in spring and once in autumn)

Another benefit of a slow release lawn fertiliser is that a consistent level of growth and greening occurs across the life of the application with no spike in growth and no nutrient-run off.

It is important not to use cheap slow release lawn fertilisers as these products tend to initially release a lot of nutrients and dwindle-off quickly with nutrient delivery, resulting in an initial surge in growth which will not be maintained.

For a good selection of slow release granular fertilisers have a look at our partners at LawnPride.

Traditional Lawn Fertiliser

Traditional lawn fertiliser is often the cheapest lawn food choice but not necessarily the best.

Key features of traditional lawn fertilisers are that:

• They require high application rates
• They only supply your lawn with short-term feed
• They create a crystalline or powdered appearance
• A spike in growth and greening occurs (rapid initial response which tappers-off quickly)
• They require frequent applications

Traditional lawn fertilisers also tend to dump their nutrient load immediately after watering into the lawn which often leads to high nutrient run-off into waterways and drains.

Application rates for traditional fertilisers are every four to six weeks and rely on the lawn being able to absorb the nutrients as they move through the soil.

However frequent applications of traditional lawn fertiliser can have detrimental effects on the soil chemistry and therefore health.

For a good selection of traditional fertilisers have a look at our partners at LawnPride

Organic Lawn Fertiliser

A ‘true’ organic lawn fertiliser is one that has been certified as 100% organic – so be sure to have that guaranteed on the label when purchasing.

The simplest way to check that it is 100% organic is by looking for the Australian Organic Certified logo on the bottle or pack.

A recommended organic lawn fertiliser is a blend of both a natural (organic) and synthetic (manufactured) fertiliser.

Therefore, the use of organic lawn food and soil improver combines the features of both a slow release fertiliser as well as natural ingredients such as seaweed, fish, manure and bio-stimulants.

Since organic lawn fertilisers are natural products it is hard to over-fertilise and in fact, they make your soil and plant health strong. As organic lawn fertilisers can be more expensive than other fertilisers it is possible to make your own by composting manure – such as from cattle or chooks.

The best time to apply your organic lawn fertiliser in autumn is either late March or early April or during spring (when the ground has finally warmed-up). You can also make another application of organic lawn fertiliser during winter – preferably late June.

For a good selection of organic fertilisers have a look at our partners at LawnPride.  

IN SUMMARY

Do:

• Use soil pH test results to choose the right fertiliser
• Spend time accurately measuring the size of your lawn
• Try an organic fertiliser during the hot summer months
• Buy a quality fertiliser spreader that best fits your needs
• Accurately calibrate your spreader to make sure you apply the right amount
• Keep your spreader well maintained
• Keep records of what and how much you apply and when you apply it

Don’t:

• Test your soil after you have fertilised
• Guess on how much fertiliser you need and what setting you use
• Apply fertiliser in hot, humid weather
• Apply fertiliser near water features, on hard surfaces or on frozen ground
• Use phosphorus unless your soil test indicates a deficiency
• Apply more than four times a year
• Bag your clippings