Why Are My Hibiscus Leaves Turning Yellow?

Yellow hibiscus leaves are a common issue for gardeners in Australia. The causes range from watering mistakes and poor drainage to nutrient deficiencies, pests, and seasonal changes. By identifying whether older or newer leaves are affected, you can quickly diagnose the problem and apply the right fix to keep your hibiscus healthy and green.

Main Causes of Yellow Hibiscus Leaves

Overwatering: Waterlogged soil suffocates roots, causing lower leaves to yellow and drop.
Underwatering: In hot or windy conditions, pots dry too fast. Leaves yellow, curl, and drop.
Poor drainage: Compacted soil or blocked pot holes prevent oxygen flow and lead to root stress.
Nutrient deficiencies:
- General pale yellowing → nitrogen deficiency.
- Yellow with green veins → magnesium or iron deficiency.
Pests: Aphids, whitefly, and spider mites drain sap, causing patchy yellowing and weakened leaves.
Seasonal dormancy: In cooler months, hibiscus naturally shed older leaves, especially in autumn and winter.

Quick diagnostic tip: Yellowing of old leaves first usually points to water or nitrogen issues, while new leaf yellowing often means magnesium or calcium deficiency.

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Fixes for Yellow Hibiscus Leaves

1) Adjust watering practices
Water deeply but let the topsoil dry slightly before the next watering. In summer, hibiscus in pots may need water 2–3 times a week. In winter, water sparingly.

2) Improve drainage
Use a free-draining soil mix with coarse sand or perlite. Always raise pots off the ground and ensure no water sits in saucers.

3) Resume regular feeding
Hibiscus are heavy feeders. A balanced fertiliser such as
CompleteGrow NPK 20-20-20 supplies even nitrogen, phosphorus, and potassium for steady green growth and flowering.
For plants showing persistent yellowing or poor flowering, upgrade to our
Advanced Formula NPK 4-18-38 + Calcium & Magnesium. The added Ca and Mg strengthen foliage and correct micronutrient deficiencies that cause yellow leaves.

4) Correct nutrient deficiencies
– Pale green leaves all over → boost nitrogen with balanced feeding.
– Interveinal chlorosis (green veins, yellow tissue) → apply Cal-Mag or use our Advanced Formula with added calcium & magnesium.
– Weak buds or dropping flowers → ensure adequate potassium via balanced feeding.

5) Manage pests
Check under leaves for mites, aphids, or whitefly. Spray with horticultural oil or insecticidal soap, and prune back heavily infested stems to restore plant vigour.

6) Recognise seasonal dormancy
If yellowing occurs in late autumn, it may simply be natural leaf drop before winter rest. Reduce water and stop feeding until spring growth resumes.

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Hibiscus FAQs

Why are my hibiscus leaves turning yellow and falling off?
This is usually due to overwatering or normal seasonal dormancy. Improve drainage if soil is soggy, or reduce watering if it’s late autumn and the plant is slowing down.

Should I cut off yellow hibiscus leaves?
Yes. Remove fully yellow leaves to tidy the plant and reduce pest harbourage, but do not cut off healthy green ones.

Why are my new hibiscus leaves yellow?
This often signals magnesium or calcium deficiency. Use Cal-Mag supplements or feed with our
Advanced Formula NPK 4-18-38 + Calcium & Magnesium to restore green growth.

Why do hibiscus leaves turn yellow in pots?
Potted hibiscus are more sensitive to water stress and salt build-up. Ensure pots drain freely, water consistently, and flush the soil occasionally to prevent excess salts.

How do I stop hibiscus leaves turning yellow?
Keep your hibiscus in full sun, water deeply but not constantly, and feed every 2–3 weeks with
CompleteGrow NPK 20-20-20. For longer-term strength and flower performance, step up to our
Advanced Formula NPK 4-18-38 + Calcium & Magnesium.