All plants need magnesium for vital functions like photosynthesis (it's central to chlorophyll) and energy transfer, but heavy feeders like tomatoes, peppers, cucumbers, and squash often show deficiencies first, with yellowing leaves (chlorosis) between veins. Other susceptible plants include citrus, roses, azaleas, and brassicas like broccoli, while legumes and root crops like carrots also require it for healthy growth.
Best Plants for Epsom Salt: Tomatoes & Peppers: Prevents blossom-end rot. Roses: Encourages brighter, larger blooms. Houseplants: Keeps foliage vibrant. Tips for Success: Use sparingly; too much magnesium can harm plants.
Early Symptoms
Early signs of magnesium deficiency include leaf veins staying green, while the regions between them turn yellow.
The application of dolomitic limestone is the most cost-effective method for applying needed Mg. The Mg content of dolomitic limestone varies from 8-10%. To be effective, this Mg source should be broadcast and incorporated before planting. Some fertilizers are a combination of potassium sulfate and magnesium sulfate.
Coffee grounds are much too acidic to add directly to soil as a fertilizer. But, coffee grounds contain potassium, magnesium, and are super high in nitrogen.
The truth is that Epsom salt is just inorganic minerals. While it can provide magnesium and sulfur for your plants, it should only be part of a complete nutrient regimen. Because of its solubility in water, Epsom salt may only be available for a short time in the root zone and would need to be applied more often.
Commonly seen on tomatoes, apples, plums, grape vines, raspberries, roses and rhododendrons. Cause: Shortage of magnesium in soil, particularly on light, sandy soils. Over-use of potassium-rich fertilisers (such as tomato feed) can cause magnesium deficiency, as plants take up potassium in preference to magnesium.
Magnesium deficiency can occur, especially in sandy soils, when soil is overwatered or after heavy rainfall events.
Epsom Salts can be applied every 8 weeks in the growing season to plants that are showing signs of magnesium deficiency, all other times continue feeding with a balanced fertiliser throughout the growing season.
Calcined magnesite (typically 80% MgO). This is the most concentrated magnesium fertiliser, but it is only slowly available in the soil. Epsom salts (16% MgO). This is a soluble form of magnesium sulphate and is used as a foliar spray where deficiency symptoms may have appeared on a high-value crop.
50 to 100 grammes of Epsom salt per square metre is recommended – on lighter soils normally add the higher quantity and on heavier soils the lower quantity. If the soil is well adjusted, it is also often sufficient to just supply it with lime, NPK or compound fertiliser containing magnesium.
Houseplants (Especially Ferns & Palms)
Indoor plants like ferns, palms, and rubber love the occasional magnesium boost. A diluted spray can perk up dull foliage. Bonus tip: if they're in a concrete pot, ensure the drainage is good to avoid build-up.
Magnesium levels in soil decline over time as a result of crop removal, soil erosion, and leaching. Low soil pH, and/or high levels of potassium (K) and calcium (Ca), low temperatures, and dry soil conditions can all contribute to Mg deficiency.
Baking soda, also known as sodium bicarbonate, can be used as an Epsom salt alternative as well. Baking soda is not only used for therapeutic purposes as well as a remedy for sunburn and itchy skin but also to ease sore muscles by adding into baths.
Mg deficient plants show light green to yellow chlorosis of interveinal tissues, while the leaf veins remain green. Whitish to light brown necrotic blotches occur on the interveinal, marginal areas. Leaves are bent down. Magnesium deficiency Magnesium deficiency is most prevalent in deep, sandy, acidic soil.
Good sources of iron for plants
Liquid Iron (iron sulfate or chelated iron) is a liquid form that you can spray directly on the plant foliage to treat plants. This is a short-term fix, but it will give your plants a booster and back on track.
Soil tests are the most reliable way to determine Mg availability from soil reserves. Include the soil's Mg status whenever you check pH, P and K levels. Remember, crop response to fertilizer Mg occurs most often on acidic, low-exchange-capacity soils that are low in organic matter and soil test Mg.
Plants That Benefit From Epsom Salt
The causes of magnesium deficiency include: Chronic diarrhea. Frequent vomiting. Malabsorption, due to a digestive condition, such as inflammatory bowel disease (IBD), or a procedure that removes part of the small intestine, namely weight loss surgery.
Symptoms of a deficiency
When there is a shortage, the leaf green in the medium-old leaves under the flowering top will be broken up, and the magnesium will be transported into the young parts of the plant. This breakdown is visible as rusty brown spots and/or vague, cloudy, yellow spots between the veins.
Succulents generally don't need Epsom salt. While magnesium can help if the soil is deficient, most succulents thrive in well-draining, low-nutrient soils. Overuse can stress or burn leaves.
Even though Biel didn't specify the reason for the bath, epsom salt is known to ease stress, relax the body, help muscles and nerves function properly and eliminate toxins.