When to Fertilize Hydrangeas in Australia

Hydrangeas reward the right fertiliser timing with big, colourful blooms. In Australia, the schedule depends on the growth cycle and the season.

Spring: Growth begins, focus on leafy shoots and stems.
Summer: Flowering takes centre stage, potassium becomes key.
Autumn: Plants wind down, roots need strengthening for dormancy.

By matching fertiliser type and timing to these phases, you’ll set hydrangeas up for consistent flowering and long-term health.

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Seasonal Feeding Schedule

Hydrangeas are heavy feeders. Use this seasonal guide to get the best results:

Early Spring: Apply a balanced fertiliser like CompleteGrow NPK 20-20-20 to push fresh growth.
Late Spring – Early Summer: Switch to CompleteGrow Advanced 4-18-38 + CaMg for bud and flower development.
Mid–Late Summer: Reapply potassium-rich fertiliser to keep flowers vibrant and lasting longer.
Autumn: Finish with a light feed of balanced fertiliser to prepare roots for winter.

Potted hydrangeas need fertiliser every 2–3 weeks with a diluted liquid mix, as nutrients wash out quickly with watering.

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Fertiliser Tips & FAQ

Don’t overfeed nitrogen: Too much = leaves, not flowers.
Check soil pH: Acidic soils = blue flowers, alkaline = pink.
Always water first: Protects roots from fertiliser burn.
Mulch after feeding: Helps retain soil moisture.

FAQ

How often should I fertilize potted hydrangeas? Every 2–3 weeks with diluted liquid fertiliser.
Does fertiliser change flower colour? Not directly—pH does. Fertiliser supports plant health so pH changes show more clearly.
What’s the best fertiliser for hydrangeas? Use CompleteGrow NPK 20-20-20 in spring, then switch to 4-18-38 + CaMg during flowering.

Final Recommendation: For Australian gardens, pair CompleteGrow All Purpose Liquid NPK 20-20-20 in spring with CompleteGrow Advanced 4-18-38 + CaMg in summer for lush growth and show-stopping blooms.