The Epsom Salt Myth

Picture this in your head. Your garden is growing, the tomatoes, squash and peppers are green, lush and doing great. You have had blooms for awhile and those first fruits have set and are slowly growing. You check your tomatoes a few days later after a period of hot days with low humidity and notice that the biggest tomato has a brownish black lesion on the bottom. Your garden has been invaded by Blossom End Rot. A quick Google search tells you the best cure for Blossom End Rot is Epsom salts so you rush to the store to buy some. You have to save your tomatoes!!!! This is where I’m going to stop the story because while Google might tell you the Epsom Salts will stop your Blossom End Rot this is one time where Google doesn’t know best. The Epsom Salt Myth needs to end here.

Blossom End Rot or BER is a common disorder found on tomatoes and it is more common in certain varieties of tomatoes than others. While BER is most commonly found on tomatoes it can also impact peppers, squash and other vegetables in the garden. Unlike other issues commonly found in the garden BER isn’t actually caused by a disease but rather caused by a lack of calcium when the fruit is forming. This lack of calcium in the fruit usually isn’t caused by a lack of calcium in the soil, our soils were formed from limestone which is composed of calcium as one of its major components. This lack of calcium can come from a couple of sources.

• The first issue could be that the top of the tomato out grew the root system during the early growing season and while it’s cooler the root system can keep up. Once we hit the hot days of summer the root system can’t supply the plant with enough water and calcium to keep up. The plant then sends the water, and the calcium it carries, to the leaves instead of the fruit causing BER. Heavy fertilization in the spring can cause this issue or make it worse.
• The second cause could be disturbance of the plant’s roots leading to a lack of water being taken up by the plant. When you are weeding in the garden, try not to cultivate or use your hoe too deep in the ground near the plants to avoid damaging the roots.
• The third cause and most likely is inconsistent watering. Keep the soil moist but not water logged. Sometimes we get heavy rain from thunderstorms and there is nothing we can do about it but to just keep a consistent watering schedule and control what we can. Mulching around the plants can help to control the moisture levels in the soil and prevent weeds which lessens the amount of work you have to do.

There is no benefit to adding Epsom salts to your tomatoes. Epsom salts contain Magnesium Sulfate and have no calcium to help prevent Blossom End Rot. There usually also is no benefit to adding additional calcium to your soil in the form of Tums or Rolaids. If you are concerned about your soil and the calcium level the best bet is to get a soil test or apply gypsum to your garden to add additional calcium. The best way to avoid BER is to water consistently, wait till fruit is setting on your plants to fertilize, pick varieties that are less likely to get BER and avoid damaging the roots of the plants. Even if you do have issues with Blossom End rot in your garden, remember that it will only last a short while (as painful as that can be) and will soon be gone from your garden for another year.

The Epsom Salt Myth is one of the most common gardening stories that I hear in the gardening world and unfortunately is one that seems to linger year in and year out. Remember to keep a consistent soil moisture level and your chances of Blossom End Rot will go down. If you keep a garden journal write down what varieties you had issues with and try not to plant them in the future. If you hear any of your gardening friends talk about Epsom salts and Blossom end rot, share these tips.

Have questions? Contact our office where our Horticulture Extension Agent will assist you with questions.

Phone: (316) 321-9660

Email: callae@ksu.edu