From our perspective as plants, magnesium (Mg) is the central atom of the chlorophyll molecule. It is the very heart of our ability to perform photosynthesis, the process that converts sunlight into the chemical energy we use to grow and bloom. Without sufficient magnesium, our chlorophyll production falters, leading to a pale appearance, yellowing between the veins of our leaves (interveinal chlorosis), and a general lack of vigor. Sulfur (S) is a critical component of amino acids and proteins, which are the building blocks of our cellular structure and enzymes. It is essential for developing strong roots and producing those vibrant blooms you admire. Epsom salts (magnesium sulfate) provide both of these essential secondary macronutrients in a highly soluble form that our root systems can readily absorb.
We do not require large, constant amounts of magnesium and sulfur like we do the primary macronutrients (Nitrogen, Phosphorus, Potassium). Our need for Epsom salts arises specifically when there is a deficiency in the soil. This deficiency can occur for several reasons: the potting mix may be depleted over time, the water you use may be soft and lack minerals, or the pH of the soil may be off, locking these nutrients away and making them unavailable to us. The symptoms we show are our way of communicating this need. If our older leaves begin to yellow while the veins remain green, it is a strong signal that we are struggling to produce sufficient chlorophyll due to a lack of magnesium.
When you provide a dilute solution of Epsom salts, you are offering a direct and easily accessible nutrient supplement. A common recipe is 1 teaspoon of Epsom salts dissolved in a gallon of water, applied as a soil drench instead of a regular watering once a month. This method allows our roots to efficiently take up the Mg²⁺ and SO₄²⁻ ions. Some caregivers also use a foliar spray, a much weaker solution misted directly onto our leaves. Our leaves can absorb these nutrients through their stomata, providing a quicker remedial effect for deficiency symptoms. However, the soil drench is generally preferred as it supports overall root health and function.
It is crucial to understand that we can only thrive within a specific nutritional balance. Epsom salts are a supplement, not a regular fertilizer. Over-application can be detrimental. Excess magnesium can interfere with our uptake of other equally critical nutrients, particularly calcium (Ca). This can lead to a calcium deficiency, manifesting as distorted new growth, bud blast (where flower buds dry up and fall off before opening), or weak stems. Therefore, Epsom salts should only be used if we are exhibiting signs of a deficiency or as a very occasional tonic, not with every watering. Always ensure we are receiving a balanced, African violet-specific fertilizer to meet our primary nutritional needs.
