Magnesium Deficiency in Citrus
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Citrus Magnesium Deficiency: Symptoms, Causes, and the Correct Treatment
If your citrus tree has yellowing older leaves with green veins, especially during flowering or fruiting, magnesium deficiency is the most likely cause. This problem is extremely common in citrus trees grown in pots or fed with potassium-rich fertilisers.
Magnesium is essential for photosynthesis and energy movement within the plant. When magnesium is deficient, citrus trees cannot efficiently support leaf health, fruit development, or overall growth, even if nitrogen and potassium are present.
- Yellowing on older leaves while veins remain green
- Discolouration starting at the leaf edges and moving inward
- Marbled or inverted โVโ patterns on mature leaves
- Reduced fruit size or uneven fruit development
- Leaf drop during periods of heavy fruit load
- High potassium fertilisers competing with magnesium uptake
- Magnesium leaching from pots due to frequent watering
- Low-magnesium potting mixes or sandy soils
- Increased magnesium demand during flowering and fruiting
- Use a balanced magnesium supplement such as Cal-Mag Hydroponic Nutrients Fertiliser to supply readily available magnesium alongside calcium.
- This is especially important for potted citrus trees and trees carrying heavy fruit loads.
- Calcium supports fruit structure, while magnesium restores green leaf colour and energy production.
Unlike iron deficiency, magnesium deficiency appears on older leaves first and can often be corrected on existing foliage if treated early. Consistent supplementation during high-demand periods helps prevent repeat deficiencies.
Do Citrus Trees Need Magnesium?
Yes. Citrus trees require magnesium for healthy leaf colour, energy production, and fruit development. Magnesium is essential throughout the growing season, with demand increasing during flowering and fruiting.
Magnesium sits at the centre of the chlorophyll molecule. Without adequate magnesium, citrus trees cannot photosynthesise efficiently or move carbohydrates from leaves to developing fruit. This results in yellowing leaves, reduced vigour, and poor fruit quality.
- Potassium-rich citrus fertilisers compete with magnesium uptake
- Frequent watering leaches magnesium from pots
- Sandy soils and soilless mixes contain little magnesium
- Heavy fruiting significantly increases magnesium demand
Magnesium is mobile within the plant, which is why deficiency symptoms appear on older leaves first. If magnesium supply is corrected early, existing leaves can partially recover and new growth will emerge healthy and green.
How to Treat Magnesium Deficiency in Citrus Trees
The most effective way to treat magnesium deficiency in citrus trees is to supply readily available magnesium while keeping overall nutrition balanced. Treating magnesium in isolation without addressing uptake balance often leads to recurring problems.
Citrus trees respond best when magnesium is supplied alongside calcium. This supports nutrient transport, leaf recovery, and fruit development without disrupting uptake between competing nutrients.
- Apply a balanced magnesium supplement such as Cal-Mag Hydroponic Nutrients Fertiliser to supply readily available magnesium and calcium.
- Especially important for potted citrus trees and trees carrying heavy fruit loads.
- Continue using a citrus-specific fertiliser for core nutrition.
- Avoid over-applying potassium-only fertilisers during correction.
- Leaf colour improvement begins within 2โ3 weeks
- Mild deficiencies may partially correct on existing leaves
- New growth emerges greener and stronger
- Fruit development becomes more even and stable
Common Questions About Citrus Magnesium Deficiency
What does magnesium deficiency look like in citrus leaves?
Magnesium deficiency appears on older leaves as yellowing between veins, often starting at the leaf edges while veins remain green.
Do citrus trees need magnesium?
Yes. Magnesium is essential for photosynthesis, energy movement, and fruit development in citrus trees.
Can magnesium deficiency be fixed?
Yes. With correct supplementation, magnesium deficiency can be corrected and new growth will return to normal.
How long does it take to correct magnesium deficiency in citrus?
Improvement is usually visible within 2โ3 weeks, with full recovery following as new growth develops.
Why does magnesium deficiency keep coming back?
Recurring deficiency is usually caused by high potassium feeding, nutrient leaching in pots, or lack of ongoing magnesium supply during fruiting.
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