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 balanced phosphorus to support root health and flowering.

Recommended Fertilisers from Complete Grow:

• NPK 20-20-20 Liquid Fertiliser: Ideal for overall growth and productivity in both young and mature avocado trees.
• Cal-Mag Nutrients Fertiliser (supplement): Corrects calcium or magnesium deficiencies, common in potted or sandy soils. NPK 20-20-20 contains no calcium or magnesium, so add Cal-Mag at 0.5–1 mL per litre to prevent the shortages avocados often show, especially in pots, sandy soil and high-rainfall areas. Dilute and apply it separately; never mix the two concentrates.

Seasonal Feeding Schedule

Fertilising avocado trees at the right time ensures steady growth and abundant harvests. Their nutritional needs change throughout the year, especially between active growth and fruiting phases.

Young Trees (1–3 years)

• Apply NPK 20-20-20 every 2–4 weeks from spring to autumn to encourage foliage and branch growth. Start newly planted trees at 2 mL per litre.
• Use liquid feeds for faster absorption and to avoid nutrient loss in shallow root zones.
• Always water thoroughly before and after fertilising to protect roots.

Mature Trees (4+ years)

• Spring: Feed balanced NPK 20-20-20 every 2–4 weeks to support flowering and fruit set.
• Summer: Keep feeding every 2–4 weeks for fruit development and the summer flush, which carries next spring’s flowers.
• Autumn: Stretch feeds out to every 4 weeks as growth slows, then stop.
• Winter: Pause feeding in-ground trees.
• Bigger trees need more mix, not a stronger one: use the same 4 mL per litre, but apply enough to wet the soil out to the drip line.

Why every 2–4 weeks? A liquid feed is taken up or washed below the roots within a few weeks. Small, regular doses suit avocados’ shallow, salt-sensitive roots far better than a few large ones, and they keep food available through flowering, fruit set and the summer flush.

Tip: Over-fertilising can cause excessive leaf growth at the expense of fruit production. Apply moderate, regular feeds instead of large doses.

For convenience and reliability, many growers use CompleteGrow 20L All Purpose NPK Liquid Plant Food. Its balanced formulation supports both young and mature trees, ensuring strong roots, healthy foliage, and productive harvests.

How Much NPK 20-20-20 to Mix

Mix 4 mL per litre for trees in the ground and 2 mL per litre for potted or newly planted trees. For common containers, that works out to:

At the in-ground rate, a 1 L bottle makes 250 L of feed, a 4 L bottle makes 1,000 L (about 100 ten-litre cans) and a 20 L drum makes 5,000 L. Always water the soil first if it is dry, then apply the mix around the drip line.

Read the Leaves: Avocado Nutrient Problems

Avocados show most feeding problems in their leaves and fruit. Match the symptom before adding more fertiliser.

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: Feed at the shorter end of the 2–4 week range as flowers open and fruit sets. Keep using the same balanced NPK 20-20-20 through flowering and fruit set.
• Autumn: Keep feeding while the tree is still growing, stretching to every 4 weeks, then stop as growth slows. 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: Feed every 2–4 weeks from spring to autumn at 4 mL per litre. Apply it around the drip line, not near the trunk, and water in deeply after application.
• In Pots: Use liquid fertiliser every 2–3 weeks at half strength (2 mL per litre). Flush monthly with water to avoid salt build-up.