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Much Ado About Epsom Salt

Healthy and happy gardening

While many of you are confined to your homes, you may have found escape outdoors to your garden.  Whether harvesting fruits of your labor or just making your yard and surroundings beautiful with plants, gardening can be therapy. Having healthy plants is always your goal and with healthy plants comes vigorous plants. More than ever home remedies seem attractive, especially those you keep around your home. One we hear about a lot is Epsom salt. I would like to address this product and hopefully clear up some things.

What is Epsom salt?

Epsom salt was first discovered in the town of Epsom in England. It is not traditional salt like we are familiar with. Epsom salt is a mineral salt and is composed of magnesium, sulfur, and oxygen. It is very soluble in water and breaks down into magnesium and sulfur very readily. Because it is so soluble, it is highly leachable in sandy soils and may quickly leach past the root zone and become unavailable.

Epsom Salt as a Fertilizer?

Both magnesium and sulfur are secondary nutrients required for the growth of plants. Palm trees especially need higher amounts of magnesium. Because of this, Epsom salt was often used to increase the magnesium in the soil for palms.  While the University of Florida recommends that palms should have 4% magnesium at fertilization, slower released forms might be more ideal. My recommendation is to follow the University of Florida’s palm fertilizer recommendation of 8-2-12 fertilizer with 4% magnesium. This would generally be formulated specifically for palms and palms would get the complete spectrum of nutrients they need. This fertilizer should provide a slower release form of magnesium than Epsom salt would give. To find this analysis fertilizer you may ask your local garden centers or go online.  Go here to read about the University of Florida’s recommendations for fertilizing landscape palms.

What about my other plants?
Upclose photo of Citrus leaves with symtoms of Magnesium deficiencies

Citrus leaves show an extreme Magnesium deficiency.

As of late, I have found an almost miracle aurora surrounding the idea of applying Epsom salt to plants. Claims of curing blossom end rot, more fruit production, or larger and healthier plants have been a few of the claims. 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. Calculating how much and how often would be difficult and based on soils cation holding capacity (c.h.c.). This capacity varies with each soil.  For this reason complete fertilizers, fertilizers with most of the required nutrients, and containing slower released nutrients, might be a better choice for nutrient management in your vegetable gardens and landscapes.

A Miracle of the Earth?

In conclusion, Epsom salt will not increase plant growth better than other forms of available magnesium. Of course, if your plants are deficient in Magnesium, they will grow more vigorously with its addition. Likewise, a plant that is not deficient will not perform more robustly because of its addition. When using Epson salt you should realize that it does readily leach in sandy soils. Overuse will likely leach past the plant’s root zone and never be utilized by the plant. It is also possible that you could add too much.

What about Blossom End Rot?

Another failed recommendation is when Epsom salt is touted as a cure to Blossom end rot (BER).  BER is caused by a calcium deficiency that is most often a result of cultural practices, such as, uneven watering or over-fertilization of nitrogen.  Even though the calcium might be available in the soil, the plant cannot uptake it into the fruit. The addition of any magnesium will not help. In fact, too much magnesium like that from Epsom salt, can tie up calcium in the soil and further aggravate the problem.

Learn what your soil needs!

Before you choose sources of fertilizers for your garden you might consider having a soil profile done by the University of Florida. They can help you get a more accurate assessment of your nutrient needs. For $10 plus your shipping cost you can get nutrients analysis as well as pH and Soil Buffering tests on your soil. With their recommendation you may find out that you don’t need to add certain nutrients at all. Simply click on the link below to learn more about testing your soil through the UF Soil Extension Lab, click here

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4 Comments on “Much Ado About Epsom Salt

    • It looks like an interesting site. Maybe I will find time to return and read some articles. Thanks for you interest. David Austin

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