Best Fertiliser for Avocado trees : Complete Guide to Growth, Feeding & Yield

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What’s the Best Fertiliser for Avocado Trees?

Avocados are subtropical evergreens that thrive with regular feeding — especially during flowering and fruiting. The best fertiliser for avocado trees provides a steady supply of key macronutrients along with essential trace elements to prevent leaf yellowing, weak growth, and poor fruit development.

Avocados benefit most from a balanced NPK fertiliser with moderate nitrogen for leaf development, potassium for fruit quality, and low to moderate phosphorus to support root health without overloading the plant.

Recommended Fertilisers from Complete Grow:

NPK 20-20-20 Liquid Fertiliser: Ideal for overall growth and productivity in both young and mature avocado trees.
Advanced Formula NPK 4-18-38 + Cal-Mag: High-potassium, low-nitrogen blend for flowering, fruit set, and strengthening cell walls in the fruiting stage.
Cal-Mag Nutrients Fertiliser: Corrects calcium or magnesium deficiencies, common in potted or sandy soils.

When & How to Fertilise Avocado Trees

Proper timing and method are just as important as the fertiliser you choose. Over-fertilising or applying at the wrong time can reduce fruit production and cause root damage. Here’s how to feed your avocado tree for best results.

Avocado Tree Feeding Calendar (Australia)

Early Spring (Sept–Oct): Begin feeding to support new shoot growth and root activity.
Late Spring to Early Summer: Increase feeding frequency as flower buds form. Use a fruiting formula (e.g., 4-18-38) to improve pollination and set.
Autumn: Apply a final dose to strengthen the tree ahead of winter. Avoid high nitrogen blends at this stage.
Winter: Pause fertilising for in-ground trees. For potted trees kept in warm areas, feed lightly only if still actively growing.

How to Apply Fertiliser

In the Ground: Apply fertiliser around the drip line, not near the trunk. Water in deeply after application.
In Pots: Use liquid fertiliser every 2–4 weeks at half strength. Flush monthly with water to avoid salt build-up.

Common Avocado Tree Fertilising Questions (and Misconceptions)

What fertiliser should I use for avocado trees?

A balanced NPK fertiliser such as Complete Grow 20-20-20 works well for overall development. Switch to a low-nitrogen, high-potassium fertiliser like 4-18-38 during fruiting. Always choose a formula that includes trace elements like boron, zinc, and magnesium.

Is seaweed fertiliser good for avocado trees?

Seaweed extracts can be used as supplements but are not complete fertilisers. They don’t provide the core macronutrients (NPK) avocados need. For best results, use a Complete Grow NPK blend as your base fertiliser and only use seaweed additives if you’re already covering nutrient needs.

How do I fertilise avocado trees in pots?

Use a liquid fertiliser diluted to half strength, such as Complete Grow 16-4-14 or 20-20-20. Feed every 2–3 weeks during the growing season and flush the soil once a month to remove excess salts. Avocados in pots are more prone to nutrient build-up and should be monitored closely.

Feeding your avocado tree with a Complete Grow premium fertiliser ensures healthy green growth, consistent flowering, and stronger fruit. Whether you’re planting in the backyard or growing in a pot, regular feeding is key to a thriving tree.