What Fertilizer for Bougainvillea?

Bougainvillea is a heavy feeder when in active growth, and the right fertiliser makes the difference between a plant full of leaves and one covered in bright bracts. The best fertiliser is one that balances root and foliage health while also pushing the plant to flower. Two options work best: a balanced everyday formula, and a bloom-focused fertiliser with higher potassium to maximise colour and repeat flowering.

Best Fertiliser Options for Bougainvillea

When choosing fertiliser, the goal is to provide steady nutrition without tipping the balance toward leafy growth. Bougainvillea responds well to complete NPK fertilisers rather than single-nutrient products.

✔ All Purpose Plant Liquid Fertiliser (NPK 20-20-20):
This balanced formula supplies equal nitrogen, phosphorus, and potassium, covering all growth needs. It strengthens roots, supports healthy foliage, and prepares the plant for flowering. Use at 4ml per litre every 2–3 weeks for both in-ground and potted bougainvillea.

✔ Advanced Formula NPK 4-18-38 + Calcium & Magnesium:
This bloom-focused option is ideal when the goal is maximum colour. The high potassium encourages vibrant bracts and longer flowering periods, while calcium and magnesium reinforce strong leaves and stems. It is best used during peak growing and flowering cycles for the strongest results.

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How to Use Fertiliser on Bougainvillea

Bougainvillea grows and flowers best when fertilised consistently but lightly. Heavy applications of nitrogen-rich fertilisers should be avoided, as they encourage leafy growth instead of blooms.

Feeding routine:

In the ground: apply fertiliser every 3–4 weeks during active growth.
In pots: apply every 2–3 weeks as nutrients leach faster through drainage.
Dilution: always mix liquid fertiliser at 4ml per litre of water to prevent overfeeding.

Tip: Water the plant lightly first, then apply fertiliser solution. This ensures even uptake and protects roots. Foliar sprays can also be used occasionally for quick nutrient absorption, especially during flowering cycles.

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Fertiliser Mistakes, Solutions, and FAQs

The most common mistake is over-fertilising with nitrogen, which results in lush green growth but few flowers. Another mistake is fertilising irregularly, leading to weak cycles of growth and flowering. Consistency with a balanced formula is the key to success.

CompleteGrow’s NPK 20-20-20 is perfect for regular care, while the NPK 4-18-38 + Calcium & Magnesium provides extra strength during blooming. Used together, they form the best long-term feeding plan for bougainvillea.

Frequently Asked Questions

What is the best fertiliser for bougainvillea?
NPK 20-20-20 for general care, and NPK 4-18-38 + CaMg for boosting flowers and bract colour.

Can I use general plant food on bougainvillea?
Yes, but balanced NPK fertilisers give far better results than generic feeds, especially when flowering is the goal.

How often should I fertilise bougainvillea?
Every 2–3 weeks in pots and every 3–4 weeks in the ground during active growth.

Why is my bougainvillea not flowering even with fertiliser?
It may be getting too much nitrogen, not enough potassium, or insufficient sunlight. Switching to 4-18-38 + CaMg and ensuring six hours of sun usually solves the issue.