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How to Choose the Best Fertiliser for your Garden

Maintaining a healthy garden comes with a long to-do list of weeding, watering, pruning, and other responsibilities. One of the key tasks for success in the garden is fertilising. But how does one choose the best fertiliser? With the right fertiliser, you can allow your plants to grow and develop at their full potential. To get the best results, we’re here to help you find the right fertiliser for your garden.

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Many homeowners and gardeners face a wide variety of fertilisers advertised to be “the best”. It’s no surprise that a lot of them start to question, what exactly is the right fertiliser for me? The answer: it depends. The most important factors to consider in choosing a fertiliser are:

  • soil type
  • time of year
  • type of the plants you have
  • purpose

Fertiliser 101: What To Know About Fertilisers

Fertilisers are used to help a plant thrive in its environment. This works by providing certain elements that are not always available through the soil. There are three major elements that can be acquired with fertilising your soil: nitrogen, potassium, and phosphorus.

Importantly, to make sure you get the right fertiliser for your garden, you would need to understand what role these elements play in helping your plant grow:


– helps plants make proteins that are necessary to produce new tissues. It gives the grass its rich green colour and aids in strengthening plants for better protection against different pests.


– improves the overall vigour of a plant. It aids in making a plant healthier by working along with nitrogen to strengthen roots and foliage. This gives it a higher capability to resist drought, diseases, drop in weather, and daily wear and tear.


– helps transfer energy from one part of the plant to another. It works under the surface and stimulates strong root growth. Phosphorus improves the vitality of plants and increases the seed size.

How To Choose The Best Fertiliser

It’s best to start with a soil test. In general, an all-purpose, 5-5-5 fertiliser is an optimal option for plant growth. However, if the soil test reveals nutrient deficiencies, the fertiliser needs to be tailored to the deficiency and the plant that you are growing.

The three numbers on a fertiliser label indicate the proportion of each macronutrient (elements discussed above) that it contains. A good example is the well-known 5-5-5 fertiliser. The first number refers to nitrogen (N), the second is for phosphorus (P), and the last number is for potassium (K). We call this the “NPK ratio”.

The NPK ratio indicates the nutrients present by weight in a single bag. If you have a 10-kilo bag of fertilizer with an NPK ratio of 5-6-4, that type of fertiliser contains 5 pounds of nitrate, 6 pounds of phosphate, 4 pounds of potash, and 83 pounds of filler.

Native plants need a phosphorous sensitive fertiliser, high in nitrogen to provide them with all the necessary nutrients for healthy growth. Osmocote’s Native Controlled Release Fertiliser has an NPK of 23-0.4-6 and is a fantastic fertiliser for Australian Natives. The release of nutrients depends on temperature, more when it’s warm and less when it’s cold to mimic the growth pattern of the plants. Osmocote’s Pots, Planters and Indoors use unique Prill technology to ensure the controlled release of nutrients, which means feeding is less often and more effective. Containing less than 2% phosphorus in this fertiliser means it’s safe for use on most Australian Natives.

Finally, with this in mind, you can now decide for yourself what type of fertiliser to use for your garden. Remember to research the plants and soil you have, as well as to explore the variety of fertilisers available to help your plants develop further.