Grevillea Problems – Causes & Fixes

Grevilleas are hardy natives, but they can suffer from nutrient imbalances, poor soil, or pruning mistakes. Here’s how to diagnose and fix the most common problems.

Yellow Leaves

Iron Deficiency: New leaves turn yellow with green veins, common in alkaline soils.
Magnesium Deficiency: Older leaves yellow between veins, often in sandy soils.
Excess Phosphorus: Root damage from the wrong fertiliser can cause widespread yellowing.
Overwatering: Waterlogged roots lead to pale, weak foliage.

Fix: Use a complete low-phosphorus fertiliser with iron and magnesium. Improve drainage and water deeply but less often.

Brown Leaves or Burnt Tips

Heat Stress: Intense sun and dry soil cause leaf scorch.
Fertiliser Burn: Applying fertiliser to dry soil damages roots.
Disease: Fungal leaf spots can brown foliage in humid climates.

Fix: Mulch roots, water consistently, and always water before applying fertiliser.

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Why Is My Grevillea Dying?

Grevilleas decline for several reasons, often linked to soil, roots, or fertiliser errors. Early diagnosis is key to saving them.

Poor Drainage: Roots sitting in wet clay soils develop rot.
Wrong Fertiliser: High-phosphorus fertilisers poison roots.
Old Age: Some short-lived hybrids naturally decline after 8–15 years.
Pest Damage: Root-feeding grubs or scale insects can weaken plants.

Fix: Improve soil drainage, cut back dead wood, and apply a liquid low-phosphorus fertiliser like CompleteGrow 20-20-20 at half strength to revive growth. If roots are rotted, replacement may be the only option.

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Why Isn’t My Grevillea Flowering?

Too Much Nitrogen: Encourages leaves but suppresses flowers.
Lack of Potassium: Leads to small or absent blooms.
Pruning Mistakes: Cutting into old wood or pruning too late removes flower buds.
Shade: Grevilleas need full sun to flower heavily.

Fix: Feed with CompleteGrow 4-18-38 + CaMg for flowering. Prune lightly after blooms, and ensure at least 6 hours of direct sun.

FAQ

Q: How do I save a dying Grevillea?
A: Check drainage, cut back dead growth, and apply a low-phosphorus fertiliser to encourage regrowth.
Q: Why are the leaves on my Grevillea turning yellow?
A: Likely iron or magnesium deficiency, or excess phosphorus. Use a complete native-safe fertiliser.
Q: Can I revive a Grevillea with no flowers?
A: Yes, by reducing nitrogen, pruning lightly, and boosting potassium-rich feed.
Q: Do all Grevilleas live long?
A: Smaller hybrids may only live 8–15 years, while larger species can live decades with good care.

Final Recommendation: Most Grevillea problems trace back to soil, drainage, or fertiliser mistakes. Choose CompleteGrow low-phosphorus fertilisers, prune lightly, and maintain even watering to keep plants thriving.