Helpful or Just Hype? What Garden Experts Say

Key Points

Epsom salt can be good for plants, but only if your soil is deficient in magnesium.
A soil test is the best way to know if you need to add magnesium to your garden.
Applying Epsom salt to healthy plants can be harmful, so it’s best to avoid it unless soil test results indicate a magnesium deficiency.

Epsom salts are often touted as a cure-all for just about any garden ailment. However, this DIY soil amendment probably isn’t necessary for you to grow healthy plants.

In fact, applying Epsom salt to your garden is likely to do more harm than good. Here’s why this home remedy is actually a myth, plus gardening methods you can use instead to help your plants thrive.

Is Epsom Salt Good for Plants?

Epsom salt can help plants thrive, but only if they’re deficient in magnesium. The best way to determine this is by testing the soil in your garden with a university extension lab for a small fee. You’ll receive a detailed report showing any deficiencies and recommended amendments.

However, if your plants have the minerals and nutrients they need and other growing requirements are met, adding Epsom salt won’t make a difference.

In fact, excess magnesium in the soil may interfere with the calcium that plants need to take up nutrients, contributing to issues like blossom-end rot in tomato plants, which Epsom salts are often used to solve.

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Why Epsom Salt Doesn’t Work in the Garden

Epsom salt is also known as magnesium sulfate, which contains magnesium, sulfur, and oxygen. Magnesium and sulfur are both necessary nutrients for plants, but epsom salt is not a fertilizer and doesn’t contain the nitrogen, potassium, phosphorus, or other nutrients plants require. Epsom salt does not deter pests and is not a registered pesticide.

If your garden soil is found to be deficient in magnesium, applying Epsom salt could help the issue.

However, no scientific studies have been conducted to determine how best to treat a magnesium deficiency in home gardens. Information like how much epsom salt to use, how often to apply it, and other considerations are unknown. This increases the likelihood that you could use too much epsom salt, damaging your plants and creating an imbalance in the soil.

If you do decide to try using Epsom salt on your plants, only do so if you see symptoms of magnesium deficiency or a soil test indicates a lack of magnesium. Avoid putting it in the planting hole or applying it as a foliar spray. Instead, apply one tablespoon of dry Epsom salt on top of the soil around each plant.

5 Alternatives for Using Epsom Salt in the Garden

Choose the proper planting site. A healthy garden begins before you plant. Consider the light and soil needs of your plants and site them in a spot that provides those conditions.
Conduct a soil test. A soil test with a university extension will give you valuable information, like soil pH and nutrient levels, that you can use to identify any amendments that may benefit your plants.
Provide sufficient water. Giving your plants enough water while they’re actively growing will encourage proper nutrient uptake. Watering properly is one of the best ways to ensure that plants like tomatoes and peppers can absorb the calcium they need to prevent conditions like blossom-end rot.
Mulch around plants. Adding organic mulch such as salt hay, shredded leaves, or shredded straw helps soil retain moisture, keeps weeds down, and builds soil organic matter over time.
Fertilize appropriately. Add compost to garden beds before planting. While plants are growing, decide what kind and how much fertilizer to apply based on soil test results, the types of plants you’re growing, and package directions.

FAQ

Plants with a magnesium deficiency will have yellow leaves with green veins, as the lack of magnesium interferes with the production of chlorophyll. This typically begins on the lower leaves of the plant. However, the only way to be certain that you need to add magnesium to the soil is to get your soil tested by a university lab.

Applying Epsom salt to plants that aren’t deficient in magnesium can prevent plants from taking up the nutrients they need. It can also increase soil salinity, which can harm plants by inhibiting water uptake. Excess magnesium has also been shown to reduce populations of beneficial microbes in the soil around plant roots and can also make aluminum, a toxic metal, available for plants and water supplies to absorb.