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When used in your bathtub, Epsom salts provide the body and skin with many health benefits. But did you know that they can also boost the health of your plants and lawn? Epsom salts are made up of hydrated magnesium sulfate (approximately 10% magnesium and 13% sulfur) and the effect of magnesium sulfate on soil improves plant growth.

Magnesium is an essential mineral for seed germination and the production of chlorophyll. Magnesium strengthens cell walls and increases plants ability to intake nitrogen, phosphorus, potassium and sulfur. 

Sulfur also helps plant growth because it aids in the production of vitamins, amino acids and enzymes. It’s also what gives certain vegetables including broccoli, cabbage, garlic and onion their flavour. Sulfur is not typically deficient in North American soils because animal manures and chemical fertilizers contain sulfur.  

Before using Epsom salts in your garden do a soil test first to confirm that the soil or plant is deficient in magnesium, and only use it if the soil test is in fact low in magnesium.

According to a senior horticulturist at National Gardening, Epsom salt can benefit soils that are

  Magnesium deficient

  Alkaline with a high pH (western regions)

  High in calcium and potassium (western regions)

  Acidic, weathered with a low pH (southeast and pacific northwest regions)


Increase Absorption of Key Nutrients

Many plants require nutrients including magnesium and sulfur to remain healthy. When Epsom salts, or magnesium sulfate is added to soil it provides plants with nutrients that boost proper function. Magnesium allows plants to intake primary nutrients including nitrogen, phosphorus and potassium. In addition, magnesium is needed to create chlorophyll since it is an essential element in the chlorophyll molecule. As a result, plants will be less likely to lose their green colour and it reduces the yellowing of leaves. 

Boost Houseplants

You can easily boost the nutrient intake of your houseplants by adding some Epsom salts once a month to the soil and to the leaves. You can start by adding one teaspoon of Epsom salt to the soil if the plant is one foot high and adding a teaspoon for each additional foot of the plant. You can also create a foliar spray because magnesium is easily absorbed by the leaves. 

Fertilizer Substitute 

When used properly, Epsom salts are an inexpensive and natural fertilizer substitute. Epsom salt doesn’t pose a risk of overuse like many commercial fertilizers, and it will not poison your groundwater.

Long Green Grass

For magnesium deficient lawns, Epsom salts will improve grass growth, make grass greener and can revive brown spots. Sprinkle Epsom salts over your lawn then soak with a hose or sprinkler. 

Boost Magnesium Hungry Plants

Many plants can benefit from the addition of Epsom salt, although it particularly benefits plants that need higher levels of magnesium to maximize growth. These plants include tomatoes, peppers and roses. There is plenty of anecdotal evidence and research that have shown Epsom salts added to tomatoes, peppers and roses result in higher yields, tastier, juicier fruits and produce more flowers. Epsom salt is also recommended to prevent blossom end rot in tomato plants, however the efficacy is unclear.

Some plants do not require magnesium sulfate because they provide adequate yields at low levels. The plants that do well with low magnesium levels are spinach, lettuce, beans and peas. 

For tomatoes, peppers and roses create a foliar spray of 1 tablespoon of Epsom salts and 1 gallon of water per foot of plant height and spray at transplanting, first flowering and fruit set 

Remove Insects & Slugs

In addition to improving the blooms and health of the plants, Epsom salts can even decrease the damage of pests because magnesium sulfate deters insects and slugs. 

Depending on the size of your plant, begin by mixing one tablespoon of Epsom salts with four cups of water and spray around the base of the plant and along the leaves if necessary. To prevent snails and slugs lightly sprinkle Epsom salts around the base of the plant.

Kill Weeds 

Mixed with the right ingredients, Epsom salt can cause serious damage to those unwanted weeds. Combine:

  1 gallon of water

  3 cups of Epsom salt

  ¼ cup of liquid dish detergent

Add the mixture to a spray bottle and take care of those weeds. Keep in mind that this solution will harm your grass and plants so use it carefully on just the weeds. Remember to wear gloves because magnesium sulfate is absorbed through the skin. 

Foliar Spray

Researchers have found that applying magnesium sulfate with a foliar spray increased the plants absorption of the magnesium. Using a foliar spray is more effective then adding dry Epsom salts to the soil because the crystal form of Epsom salts is not as easily absorbed by the soil especially if soils are high in potassium, calcium or magnesium. 

You can find Epsom salts at most grocery stores or pharmacies, or you can get larger bags specifically for your lawn and garden like the recommended product below.

Get it: Epsoak Epsom Salt