Yellowing citrus leaves can be a frustrating sign that your trees aren't getting the nutrients they need. One of the most effective solutions is using magnesium sprays, which can restore vibrant green colour and promote healthy growth. Here's how to identify the problem and apply the fix.
Why Do Citrus Leaves Turn Yellow?
Magnesium deficiency is one of the most common causes of yellowing leaves in citrus trees. When trees lack sufficient magnesium, the older leaves (usually at the base of branches) develop a distinctive yellowing pattern while the veins remain green. This condition, called interveinal chlorosis, weakens the tree and reduces fruit quality.
Other contributing factors include poor soil drainage, inconsistent watering, low soil pH, and nutrient imbalances. However, magnesium deficiency is often the quickest fix.
How to Apply Magnesium Spray
Magnesium sulfate (Epsom salt) spray is an affordable and readily available treatment. Here's the recommended process:
- Mix the solution: Dissolve 1–2 tablespoons of magnesium sulfate in 1 litre of water. For severe deficiency, use 2 tablespoons; for mild cases, 1 tablespoon is sufficient.
- Choose the right time: Apply early morning or late afternoon to avoid leaf burn from sun exposure. Avoid spraying during extreme heat.
- Spray thoroughly: Use a garden sprayer to coat both the tops and undersides of leaves until the solution drips slightly. This ensures absorption through the leaf surface.
- Repeat application: Spray every 2–3 weeks until new growth appears green and healthy, then reduce frequency to monthly maintenance.
Soil Application as an Alternative
For a longer-lasting solution, you can also apply magnesium sulfate directly to the soil. Dissolve 1 tablespoon per litre of water and pour around the base of the tree. This method is slower but provides sustained nutrient availability over several weeks.
Prevention Tips
Once your citrus trees recover, maintain healthy magnesium levels by mulching around the base (which helps retain moisture and regulate soil temperature), watering consistently, and conducting a soil test every 2–3 years. A balanced fertiliser designed for citrus can also prevent future deficiencies.
With consistent application and proper care, your citrus leaves should return to their healthy green colour within 4–6 weeks. Monitor progress regularly and adjust your treatment plan as needed.