Avocado Fertiliser Schedule: What to Apply and When

Many avocado farmers either over-fertilise thinking more is better, or under-fertilise to save money. Both approaches reduce yield and waste resources. Avocado trees have specific nutrient needs at different stages of their growth and fruit development. Applying the right nutrient at the right time makes a much bigger difference than simply applying large quantities.

The Three Key Nutrients for Avocado

Nitrogen is the most important nutrient for avocado. It drives leaf and shoot growth and is needed throughout the growing season. Avocados are heavy nitrogen feeders especially in the first few years. Phosphorus supports root development, flower formation, and fruit set. It is most important in young trees and at flowering. Potassium is critical for fruit quality, size, and disease resistance. Its importance increases as the tree matures and starts bearing fruit. A mature avocado tree typically needs approximately 0.5 to 0.8 kg of actual nitrogen, 0.19 kg of phosphorus, and 0.75 kg of potassium per tree per year for good yield.

Fertiliser Schedule for Young Trees: Year 1 to Year 3

Young avocado trees need regular but careful feeding. Apply a balanced NPK fertiliser with a ratio of 10-10-10 or similar every 6 to 8 weeks during the growing season from February to October. Do not fertilise during the coldest months of December and January when growth slows. Apply fertiliser at least 30 to 60 centimetres away from the trunk, never directly against it, as this can burn the sensitive young roots. In the first year, start with small doses of around 100 to 150 grams per tree per application and increase gradually. Add 2 to 3 kg of well-rotted organic manure per tree every 3 months to build soil health alongside chemical fertilisers.

Fertiliser Schedule for Bearing Trees: Year 4 Onwards

Once trees start bearing fruit, the fertiliser program shifts. Apply nitrogen-rich fertiliser before flowering in January and February to support flower development. At fruit set, shift to a fertiliser higher in potassium such as a 10-10-15 ratio to support fruit development and quality. In the 60 days before harvest, increase potassium application further and reduce nitrogen. High nitrogen near harvest promotes vegetative growth at the expense of fruit quality. After harvest, apply a balanced fertiliser to help the tree recover and build reserves for the next season.

Micronutrients That Avocado Trees Need

Zinc deficiency is very common in avocado and shows as small misshapen leaves and poor fruit set. Apply zinc sulphate as a foliar spray at 0.5 percent concentration in April and September to prevent this. Iron deficiency appears as yellowing between leaf veins on new leaves, common in alkaline soils. Apply chelated iron to the soil or as a foliar spray. Boron deficiency shows as bumpy or corky fruit skin. Apply borax at 2 grams per litre as a foliar spray at flowering. Magnesium deficiency shows as yellowing of older leaves. Dolomitic lime contains both calcium and magnesium and can be applied to soil every 2 to 3 years in acidic soils.

Fertigation: The Best Method for Indian Avocado Farmers

If you have drip irrigation installed, fertigation is the most efficient way to apply fertilisers. Water-soluble fertilisers are dissolved in the drip system and delivered directly to the root zone where they are immediately available to the tree. This reduces fertiliser waste significantly compared to broadcasting granules on the surface. It also allows you to apply smaller doses more frequently which is better for the tree. Start with a balanced water-soluble fertiliser of 19-19-19 NPK during vegetative growth phases and switch to a potassium-heavy formula of 13-6-40 during fruit development.

Important Rules to Follow

Always base your fertiliser program on a soil test and ideally a leaf analysis done in late spring. Do not apply fertiliser to dry soil. Water the tree first, then apply fertiliser, then water again. Never apply fertiliser during extreme heat above 35 degrees Celsius as this stresses the roots. Avoid applying high nitrogen fertilisers after fruit set as this reduces fruit quality. Excess nitrogen causes lush leaf growth but smaller, lower quality fruit. Rotate between different fertiliser products to avoid salt buildup in the root zone over time.