Adding Epsom Salt To Your Garden and Lawn: Claims vs Facts

Every spring, articles and social media posts encouraging you to use Epsom salt in your lawn and garden are ubiquitous. They claim that Epsom salt creates bigger blooms, “bushier” shrubs, greener grass, and even controls pests. The truth is, there are no scientific studies – not one – to back up the claims about Epsom Salt, and for the most part, these are, at best, urban myths.

The claims for Epsom salts include:

• use as a pesticide
• as a fertilizer for lawn and garden
• to make grass greener
• to speed seed germination
• to make shrubs “bushier”

8 facts about Epsom Salt for lawn and garden

1. Epsom salt does not encourage flower blooms or greener grass

Many articles claim that adding Epsom Salt to soil and around roots when planting tomatoes, peppers, and other vegetables boosts magnesium and sulfur levels, which stimulates blooms. The problem with this claim is that few soils are deficient in magnesium or sulfur except for very sandy soils that experience a great deal of rainfall. And with any fertilizer, more is not better – every plant requires specific amounts of nitrogen, potassium, phosphorus, magnesium, calcium, sulfur, and other elements, and what they don’t take up washes away as a pollutant. If a plant isn’t taking up enough magnesium, the problem usually is too much potassium in the soil. Adding more magnesium won’t improve the situation at all, as the plant can’t take it up. Magnesium and sulfur are micronutrients for plants – they only need small amounts for optimum health.

2. Epsom Salt is used in commercial agriculture

This is true sometimes. Agricultural crops are intensively cultivated year after year, unlike your garden. Farmers use soil tests to determine if the soil is deficient in Magnesium or Sulfur. If the soil test shows it is, the farmer may choose to add Epsom salt to their fertilizer regimen.

3. Epsom Salt does not discourage Blossom End Rot in tomatoes.

Blossom End Rot is caused by a lack of calcium and too much rain in a short period. Magnesium competes with calcium for uptake, so adding Epsom Salt around your tomatoes could worsen this problem.

[su_highlight background=”#fffd8c” color=”#000003″]Buy on Amazon: Luster Leaf Digital Soil Test Kit[/su_highlight]

4. It’s false that Epsom Salt is highly soluble, so it can’t be overused.

Highly soluble chemicals that aren’t needed by plants don’t just disappear from the environment – they wash away to somewhere else, like your local waterways or neighboring properties. This includes fertilizers. Chemicals should never be added unless absolutely necessary.

5. Epsom salt has no proven value as a pesticide.

In scientific testing, the pesticide claims for Epsom salt do not hold up. Epsom salt is found to be of no value in killing insects, including slugs, at any stage in their development. A similar lack of results has been found in claims that Epsom salts can reduce powdery mildew and apple scab.

6. Epsom salt does not help seeds germinate

As far as the claim that Epsom salt helps seeds germinate, seeds already have all they need to germinate and require nothing else. If you start seeds in a quality starting medium with a heat mat and proper moisture, the seeds will germinate just fine.

7. No studies show that Epsom salt improves the health of trees and shrubs

Claims that Epsom salt improves the health of shrubs and trees have not been reproduced and verified in any studies. Used as a foliar spray, Epsom salt solution may actually cause leaf scorch.

8. Epsom salt may actually harm your lawn, not help it

The use of Epsom salt for lawns is discouraged because grass doesn’t require magnesium. Epsom salt is sometimes used to reinvigorate pasture land (once again, a crop under heavy cultivation). But it is only a temporary solution, as literally half of the Epsom salt washes away when it rains.

The bottom line on Epsom salt

Few soils are deficient in Magnesium or Sulfur, and plants will only use as much of these nutrients as they require. The only way to know for sure if your soil is lacking in any element is to have it tested by an accredited soil lab. If your test results note a deficiency, you should only add the element/s needed and in proper quantities to bring the soil into the normal range.

Source: Busting the Epsom Salts Myth from Linda Chalker-Scott, Ph.D.; Iowa State University: Gardening Myths.