Should You Use Epsom Salt for Tomatoes? 2 Ways It Can Improve Your Garden

Epsom salt, chemically known as magnesium sulfate, is often touted as a beneficial supplement for tomato plants. The magnesium and sulfur found in Epsom salt are essential nutrients that support healthy plant growth and fruit development. However, opinions on its efficacy vary among gardening experts. 

Here’s how and when to use Epsom salt to benefit your tomato plants.

How Epsom Salt Benefits Tomatoes

The general consensus is that, when used appropriately, Epsom salt can be beneficial, but it is not a cure-all solution for all tomato-growing issues. Used in the right ratio, it has been beneficial for palm trees and other plants that need a lot of magnesium.

If your soil needs magnesium, then adding Epsom salts may be a helpful treatment. Of course, a proper soil assessment will be the final say on that, but if your tomato plants need some magnesium, here are ways Epsom salts can benefit them.

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Improves Chlorophyll Production

Magnesium is a crucial component of chlorophyll, the compound plants use in photosynthesis. By providing additional magnesium to your plants, Epsom salt can help prevent yellow leaves, leading to healthier, greener foliage and better overall plants.

Enhances Nutrient Uptake

Epsom salt can improve the plant’s ability to absorb other essential nutrients from the soil, such as nitrogen and phosphorus. This enhanced nutrient uptake is particularly important during critical growth stages, such as flowering and fruit set, ensuring that tomato plants get the nutrients they need for robust growth and abundant fruit production.

Prevents Blossom End Rot

Unfortunately, there are mixed opinions about whether Epsom salt is an effective treatment for blossom end rot prevention. While some might call it a miracle treatment, some experts say it can do more harm than good.

Tom Kalb, extension horticulturist at North Dakota State University wrote that Epsom salt doesn’t help prevent blossom end rot. Rather, it leads to more of it.

“Blossom end rot is caused by a deficiency of calcium. Epsom salt contains magnesium sulfate—no calcium at all,” he wrote. “Adding Epsom salt to the soil may create more rot since magnesium and calcium ions compete for uptake into the plant.”

David Austin, residential horticulture agent and master gardener coordinator in Highlands County, Florida, agrees.

“Epsom salt will not increase plant growth better than other forms of available magnesium,” he wrote for the University of Florida’s IFAS Extension. “Of course, if your plants are deficient in magnesium, they will grow more vigorously with its addition.”

How to Use Epsom Salt on Your Tomato Plants

If you decide that your soil needs magnesium and want to add Epsom salt to your tomato plants, here’s how you can do it. Before starting, gather the following supplies: Epsom salt, a measuring spoon, water, a watering can or spray bottle, and optionally, a soil test kit.

1. Do a soil test: Conduct a soil test to check the magnesium levels in your soil. This will help determine if your soil actually needs additional magnesium.
2. Dissolve Epsom salt: Mix one tablespoon of Epsom salt in a gallon of water. Stir until the salt is completely dissolved.
3. Apply to soil: Water the tomato plants with the Epsom salt solution at the base of each plant. This method ensures the roots can absorb the nutrients effectively.
4. Foliar spray: For faster absorption, you can also use a foliar spray. Fill a spray bottle with the Epsom salt solution and spray the leaves of the tomato plants. This method is particularly useful if you notice signs of magnesium deficiency in the foliage.
5. Repeat as needed: Apply the Epsom salt solution every two to four weeks, depending on your soil test results and the specific needs of your tomato plants.