Why Your Citrus Trees Need Epsom Salt
Citrus trees are a popular addition to New Zealand gardens, but yellowing leaves can be frustrating. One of the most common causes is magnesium deficiency, and epsom salt offers an affordable, natural solution. Magnesium is essential for chlorophyll production—the pigment that gives leaves their green colour. When your tree lacks magnesium, leaves yellow while veins remain green, a condition known as interveinal chlorosis.
Understanding Epsom Salt and Magnesium Sulfate
Epsom salt is magnesium sulfate, a naturally occurring mineral compound that dissolves easily in water and is readily absorbed by plant roots. Unlike synthetic fertilisers, epsom salt provides two critical nutrients: magnesium and sulfur. Both support healthy leaf development, flower production, and fruit quality in citrus and other garden plants.
How to Apply Epsom Salt to Your Garden
Application is simple and effective. For citrus trees, dissolve 1 tablespoon of epsom salt in 1 litre of water and apply directly to the soil around the base of the tree. Water the tree thoroughly first to prevent salt burn on roots. Apply this solution once every four to six weeks during the growing season (spring and summer). Alternatively, you can sprinkle 1 tablespoon of dry epsom salt around the base of each tree and water it in well.
For established trees or larger gardens, a foliar spray works well: mix 1 tablespoon of epsom salt per litre of water and spray onto leaves in early morning or late afternoon. This method allows leaves to absorb magnesium directly, providing faster visual results within two to three weeks.
Epsom Salt for Plants Beyond Citrus
Citrus trees aren't the only garden plants that benefit from epsom salt. Tomatoes, roses, peppers, and leafy greens all respond well to magnesium supplementation. Vegetables grown in New Zealand soils, which are often naturally low in magnesium, particularly benefit from regular applications.
Finding Quality Epsom Salt in New Zealand
When shopping for epsom salt, look for food-grade or garden-grade options from trusted local suppliers. Quality matters—pure magnesium sulfate without additives or fillers ensures your plants receive maximum benefit. Check product labels to confirm the purity and avoid products containing anti-caking agents unsuitable for soil application.
Getting Started This Season
If your citrus trees are showing signs of yellowing, start with a soil application of epsom salt this week. You'll likely notice improvements in four to six weeks. Consistent applications throughout spring and summer will keep your trees healthy, vibrant, and producing abundant fruit. Remember to water your garden well before and after application to ensure proper nutrient uptake and prevent root damage.