Fertiliser basics

Plants use nutrients they take up from the soil through their roots to grow, flower, and fruit.

Over the growing season, they need different nutrients at different rates and times to encourage fruit development, healthy foliage and strong roots.

Understanding what your fruit trees need, and when, is essential for successful cropping.

Let’s look at plant fertilisers and how your fruit trees can benefit from their correct application, including:

  • Understanding fertiliser ratios
  • What to use and when
  • How to apply fertiliser
  • The importance of PH



How to fertilise your fruit trees

Keeping plants healthy is about giving them what they need to grow. Water, light and nutrients are all essential for plant growth.

Nutrients are provided from the soil itself and through the application of fertilisers that are specially formulated to provide plants with the essential elements they need to grow, flower and fruit.

This is done by:

  • Adding organic material
  • Improving soil pH
  • Incorporating more nutrients
  • Working and turning the soil



Understanding fertiliser ratios


Fertilisers are combinations of essential elements that have been mixed at a specific ratio to encourage plants to grow, flower or fruit.

  • Fertiliser manufacturers list these ratios on the packets, usually shown as N:P:K or Nitrogen (N), Phosphorus (P) and Potassium (K). These are the macro or major chemical elements that directly impact plant growth and development.
  • Plants also require micro nutrients and trace elements to maintain optimal health. To see what these are and why they are important to plants, look at Fertiliser Components and their Uses.

Most fertiliser packaging will include a Guaranteed Analysis that lists all major, minor and trace elements included and their relevant percentages or parts per million.


What and when

All the information you'll need can be viewed in What fertiliser to use and when to use it.

How to apply fertiliser

When applying granular fertilisers:

  1. Wet the soil before and after applying fertiliser.
  2. Apply over the root zone of the tree around the dripline (directly beneath the outer perimeter of the canopy). This is where the feeding roots are found, not in close to the trunk of the tree.

When using controlled or slow release fertilisers, read the labels before using to determine how much and how often you should be using them. Some are three month formulations, some six month and one or two will feed for up to 12 months.

The importance of pH

The pH of your soil determines the availability of some nutrients.

  • Test your pH every three to four years and adjust accordingly - see Healthy Soil = Healthy Plants for more details.
  • Ph should be between 5.5 and 7.0 for most fruit trees.


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