Gardeners have used Epsom salts to enhance their plants and flowers since the early 1600s, after locals discovered the natural mineral in Epsom, England. Some gardeners believe that Epsom salt’s combination of magnesium and sulfur will boost a plant’s ability to absorb key nutrients from the soil more effectively, which helps them grow bigger and brighter. Others believe that Epsom salt has no added benefit if you plant in nutrient-balanced soil. Regardless of where you fall in this debate, there is common agreement that magnesium is a key element in a plant’s enzymes, and having your soil tested, prior to planting, is the best way to determine which nutrients are needed to provide a healthy soil for your plants and flowers to thrive. The choice to use Epsom salt rests with each individual gardener.
Analyzing your soil is the best way to figure out whether you need to consider adding Epsom salt. Check a home improvement store for a home soil test kit that enables you to check the mineral levels. Alternatively, most state universities will examine soil samples through their Corporative Extension Service and may also make recommendations on types of plants and fertilizers for the garden area.
For soil that is magnesium-deficient, Epsom salt can help balance the nutrients for plants and flowers to grow and flourish. Magnesium is the main ingredient, and it helps plants better absorb primary nutrients like nitrogen, phosphorus, and potassium, which are vital for a healthy lifecycle from germination to developing roots and stems to flowering and the production of seeds.
Plants that may require elevated levels of magnesium to promote growth might be good candidates for Epsom salt as an added nutrient. These include roses, tomatoes, and pepper plants. Gardeners need to be careful, though, because soil with too much magnesium can cause other nutrient deficiencies.
Adding Epsom salt to existing or fertilized soil that already has a good balance of nutrients will increase the soil’s magnesium levels beyond the plant’s ability to absorb other nutrients needed to survive. This can lead to a calcium deficiency since the plant cannot absorb enough of that vital nutrient. Too little calcium can contribute to blossom end rot and kill the plant.
If you've determined your garden could benefit from Epsom salts, add one tablespoon to the soil where you will plant the seeds and water generously. For larger garden areas, gardeners can sprinkle a cup of Epsom salt over a 100 square foot area then blend with the soil, and water. Remember to test the soil prior to planting to ensure additional magnesium is needed.
Using Epsom salt as a misted spray allows the plant leaves to quickly absorb the magnesium instead of having to pull it from the soil. For monthly treatments, mix two tablespoons of Epsom salt with one gallon of water, and mist on the leaves of the plants.
Epsom salt can also help eliminate snails and slugs that burrow in your garden. Mix one cup of Epsom salt with five gallons of water to spray on plant leaves and stems. Additionally, you can sprinkle dry Epsom salt around the base of plants in your garden as natural pest control. Use caution, as this process could result in elevated magnesium in your soil.
When transplanting plants and flowers to your garden, Epsom salt can help prevent the wilting and discoloration caused by root shock. Mix the salt with the soil in the new location or soak the roots of the plant with a salt and water mixture.
Prior to stocking up on Epsom salt, know that there are a couple of different types available. Agricultural or technical grade Epsom salt is for gardens, while salts with the United States Pharmacopeia (USP) label are Federal Drug Administration-verified as safe for human use. Use caution when handling magnesium sulfate, as it is absorbed through the skin.
Epsom salt can help homeowners remove tree stumps by killing the roots. Drill holes, at least 8” deep, with a 1-inch auger drill bit around the stump. Fill the holes with Epsom salt and moisten with enough water help the salt absorb into the stump. Cover with a tarp so the salt can dry out the stump. This is not a quick process and can take a few months, depending on the size of the tree. After removal of the dead stump, you may want to excavate the surrounding earth and backfill with fresh soil so the salt doesn't cause a problem in future growing endeavors.