Best Fertilizer for Chestnut Trees: Complete Guide for Australian Growers

What Makes Chestnut Trees Thrive?

Chestnut trees (Castanea species) are large, long-living trees valued for both ornamental beauty and high-yield nut production. In Australia, European chestnuts (Castanea sativa) and Chinese hybrids are the most widely grown varieties, especially in regions like Victoria, Tasmania, and parts of New South Wales. To ensure robust growth and consistent nut set, you need the best fertilizer for chestnut trees—a formulation that supports all stages from bud burst to nut drop.

Chestnuts are moderately heavy feeders. They require nitrogen (N) to build foliage and branching, phosphorus (P) to develop roots and flowers, and potassium (K) to enhance nut formation and disease resistance. We recommend CompleteGrow 20-20-20 All Purpose Fertiliser as the best fertilizer for chestnut trees. Its balanced NPK ratio gives your trees all the macro-nutrients they need in one easy mix, making it ideal for both young and established trees.

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Seasonal Fertilising Schedule for Chestnut Trees

Timing is everything when it comes to fertilising nut trees. Chestnut trees benefit from steady, balanced nutrition during their active growing season and light support during dormancy. Applying the best fertilizer for chestnut trees—such as CompleteGrow 20-20-20—at the right times will promote vigorous canopy development, healthy flowers, and well-filled nuts with strong shells.

Spring (September to November)

Apply 20-20-20 at 3g per litre of water as a soil drench around the dripline
Encourages fresh leaf growth and flower bud formation
Reapply every 4–6 weeks until summer heat sets in

Summer (December to February)

Continue monthly feeding to support nut development
Ensure consistent watering to help nutrient uptake during hot spells
Do not overapply—chestnuts prefer moderate nutrition over heavy feeding

Autumn (March to April)

Use a diluted mix (2g per litre) to support root health post-harvest
Helps the tree build reserves for next year’s growth
Discontinue fertilising before full leaf drop

Winter (May to August)

Chestnut trees enter dormancy in winter and do not need feeding. This is a great time to prune, test soil pH (ideal range: 5.5 to 6.5), and plan for spring fertilising with CompleteGrow 20-20-20.

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FAQs: Best Fertilizer for Chestnut Trees

What is the best fertilizer for chestnut trees in Australia?

The best fertilizer for chestnut trees in Australian conditions is the CompleteGrow 20-20-20 All Purpose Fertiliser. Its even NPK ratio supports every stage of chestnut growth—from leafing and flowering to nut production. It dissolves easily in water and suits acidic soils commonly found in chestnut-growing regions.

How often should I fertilise my chestnut tree?

Feed your chestnut tree every 4–6 weeks during the growing season (September to April). In cooler climates, reduce to every 6–8 weeks. Always water after application to help nutrients reach the root zone.

Should young and mature chestnut trees get the same fertiliser?

Yes—young and mature trees both benefit from a balanced fertiliser like CompleteGrow 20-20-20. Adjust dosage based on tree size: smaller trees need less (1–2g per litre), while mature trees can handle up to 3g per litre.

Can I use organic matter with 20-20-20?

All CompleteGrow fertilisers are standalone, water-soluble products. Additional compost or organic matter isn’t required and may cause nutrient imbalances. Stick with pH-balanced formulas like 20-20-20 for best results.

Where can I buy chestnut fertiliser in bulk?

Our 20L Bulk All Purpose Fertiliser is available for commercial and home growers at completegrow.com.au. Save on bulk pricing and receive free delivery Australia-wide.