Epsom Salt for Plants: Pros and Cons of Using Epsom Salt in the Garden

epsom salt in garden

Epsom salt (magnesium sulfate) is a mineral compound that is used in the garden to help plants and lawns grow better. Gardeners also use Epsom salt to boost the growth of tomatoes, roses, peppers, carrots, and citrus trees.

Epsom salt is a magnesium-rich compound that may help boost plant growth, improve nutrient uptake, make plants greener, and may even deter pests. Epsom salt has neutral pH levels so it won’t affect your garden soil pH.

Even though Epsom salt is popular in gardening, it’s not without its critics. Some people say that this Epsom salt does nothing for plants and won’t make plants greener. Also, using Epsom salt as a fertilizer is ineffective as it doesn’t contain nitrogen, phosphorus, and potassium.

What’s the truth about using Epsom salt in your garden? What are the pros and cons of using this naturally-occurring mineral to boost plant growth?

This article explores some of the reasons why using magnesium sulfate can have benefits to your garden. We’ll also debunk some of the myths regarding a few of the traditional uses of Epsom salt for plants.

What is Epsom Salt?

Epsom salt (magnesium sulfate) is a mineral compound that contains magnesium, sulfur and oxygen. Epsom salt looks like large salt crystals and is used in agriculture, medicine and construction industries. Epsom salt was originally produced in springs in the English town Epsom, hence got its common name.

Using Epsom salt for plants increases the magnesium and sulfur content in soil—two of the many nutrients that are essential for plant growth. Magnesium helps with chlorophyll production and allows plants to absorb primary essential nutrients. Adding Epsom salt to garden soil may help some plants to grow better if the soil lacks magnesium.

Although magnesium sulfate (Epsom salt) is called a salt, it shouldn’t be confused with regular table salt (sodium chloride). Unlike regular salt—that you shouldn’t use in your garden— Epsom salt has some beneficial uses for plants and grass.

Is Epsom Salt Good for Plants?

Yes, Epsom salt is good for plants if there’s a magnesium (Mg) deficiency in the soil. Adding magnesium to the ground can help plants grow better if this mineral is lacking.

Researchers say that magnesium is an essential secondary nutrient for optimal plant growth. Sometimes, a chemical imbalance, poor soil, or soil where magnesium-hungry plants grow can result in low levels of magnesium. In these cases, adding a magnesium compound such as Epsom salt could be useful for plants to address any deficiencies.

According to the University of Minnesota, magnesium deficiencies occur in acidic, loamy soils. However, in many gardens and backyards, a lack of magnesium is not usually an issue.

What Does Epsom Salt Do for Plants?

Epsom salt or magnesium sulfate can encourage healthy plant growth. Magnesium helps plants to create chlorophyll—a substance essential for photosynthesis that gives plants energy and their green color. Magnesium allows plants to produce flowers and absorb vital nutrients, like phosphorus and nitrogen. Adding Epsom salt can address soil magnesium deficiencies.

Let’s look in more detail at what Epsom salt can do for plants if there’s a lack of magnesium in the soil.

Epsom Salt Could Encourage Plant Growth

Because magnesium is vital for plant growth, adding Epsom salt could be useful for encouraging plant growth. Photosynthesis doesn’t just make plants green; it gives energy for plants to grow and produce flowers and fruit—and magnesium is essential for this process. Plants growing in poor soil could benefit from the magnesium sulfate in Epsom salt.

Adding Epsom salt can help correct magnesium deficiency in some soil types. Garden soil that has little organic matter is more likely to have magnesium deficiency. Epsom salt can also help acidic soil and soil with high level of potassium as these soil types reduce magnesium uptake.

Epsom Salt Can Provide Some Plant Micronutrients

Epsom salt contains two micronutrients that many plants need—magnesium and sulfur. Some plants such as tomatoes, roses, potatoes, peppers, carrots, and citrus trees need adequate levels of magnesium in the soil. If you have acidic or loamy soil, these types of plants could benefit from Epsom salt.

Of course, every plant has different nutritional needs, and not all plants benefit from Epsom salt. For example, legumes and leafy vegetables grow in soil with low magnesium levels. So, using Epsom salt as a fertilizer on these plants won’t have any impact on plant growth.

Interestingly, a meta-analysis published in 2019 into the use of magnesium fertilizers found that they have some benefit in agriculture. Scientists found that acidic soil can benefit from magnesium fertilization. In some cases, using magnesium as a plant feed can increase tomato yield and boost photosynthesis in leafy plants.

Researchers from Mississippi State University say that Epsom salt is used for correcting magnesium deficiencies in some circumstances. Epsom salt is a common source of soluble magnesium that works as a fertilizer in magnesium-deficient soil.

Epsom Salt May Improve Plant Nutrient Uptake

The magnesium content of Epsom salt can help plants absorb essential nutrients, such as nitrogen and phosphorus. Plants lacking magnesium can become stressed and unable to absorb the nutrients needed for growth. Using Epsom salt to address magnesium deficiencies will result in normal nutrient absorption.

However, it’s good to remember that Epsom salt only benefits plants where a magnesium deficiency exists. If you’ve got healthy, balanced soil, adding Epsom salt won’t increase nutrient uptake beyond its standard limit.

Epsom Salt May Deter Pests on Plants

Gardeners believe that Epsom salt can deter pests and even kill them on contact. Recommendations to kill garden bugs is to sprinkle Epsom salt around the base of plants or make an Epsom salt spray solution. However, there is only anecdotal evidence on the effectiveness of Epsom salt as a natural pesticide.

You could try Epsom salt as a natural pest deterrent to see if it works for you. Mix half a cup of Epsom salt with 2.5 gallons (9.5 Liters) of water and stir until it dissolves. Using a pump sprayer, coat your plant leaves to help keep bugs at bay. Alternatively, you could sprinkle Epsom salt around tomato plants or roses to help deter pests.

Despite the claims that Epsom salt is good for pest control, the Washington State University Extension (WSU) says that there’s no documented evidence for its use. So, if you decide to try Epsom salt for slugs, caterpillars, or other pests, apply it carefully to avoid overusing it or overdosing the soil with excessive amounts of magnesium.

Does Epsom Salt Make Plants Greener?

Yellowing leaves can be a sign of magnesium deficiency and it’s most common in citrus trees, and ornamental plants.

Many gardeners believe that using Epsom salt in the garden helps plants grow greener leaves. This could be true if your soil lacks magnesium. Magnesium is essential for chlorophyll production—a green pigment used in photosynthesis. However, if your soil has enough magnesium then using Epsom salt will not make any difference.

Can Epsom Salt Neutralize Soil pH Levels?

Epsom salt will not change the pH levels of the soil because it’s neither acidic nor basic. Epsom salt has a neutral pH level of 7.0 and it won’t make the soil more acidic or alkaline.

Many types of acidic or sandy soils are magnesium-deficient. However, while adding Epsom salt can address the lack of magnesium, it won’t reduce acidity.

How To Use Epsom Salt For Plants

Using Epsom salt in the garden can help plants that require a lot of magnesium such as peppers, roses, and tomatoes.

To use Epsom salt for plants dissolve 1-2 tablespoons of Epsom salt in 1 quart (1 Liter) of water and irrigate your plants for healthy growth. You can also sprinkle 1 tablespoon of Epsom salt granules around the base of plants such as tomatoes, or peppers to increase magnesium levels. Water your plants well after the application.

You can also apply Epsom salt as foliar spray by dissolving 1 tablespoon of Epsom salt per gallon of water. Spray the Epsom salt fertilizer directly on the plant’s leaves.

Before using Epsom salt on plants, it’s good to remember that not all plants benefit from the addition of magnesium. So, check the type of crops you want to grow before using Epsom salt as a fertilizer.

Also, in magnesium-rich soils, adding Epsom salt will have little benefit as there are no nutrient deficiencies to address. If you think that Epsom salt will be good for your garden, get a soil test done to see if there are any soil deficiencies.

Epsom Salt for Roses

Use Epsom salt to water roses to help address their magnesium needs. Add one tablespoon of Epsom salt to a gallon (3.8 liters) of water and use it to water your rose bushes once a month in the growing season.

Epsom Salt for Tomatoes and Peppers

Using Epsom salt granules or as a liquid spray can help tomatoes or peppers to produce healthy crops. To use the granular method, sprinkle a tablespoon of Epsom salt around the base of each plant. Apply the granules when you plant the plants, then apply after they flower, and then when the first fruits appear.

You can also make an Epsom salt spray to help ensure that tomatoes don’t suffer from a magnesium deficiency. Dissolve one tablespoon of Epsom salt crystals in a gallon (3.8 liters) of water. Thoroughly spray the tomatoes or peppers with Epsom salt three times—when planting, then after flowering, and then when the fruits start growing.

Epson Salt for Citrus Trees

Yellowing leaves can be sign of magnesium deficiency and it’s most common in citrus trees. If your citrus tree has yellow leaves, then adding Epsom salt can help encourage growth of healthy green leaves.

To use Epsom salt for citrus trees apply 1 tablespoon per 3 ft. (1 meter) of tree height. You can dissolve the Epsom salt in water or sprinkle it on the ground under the citrus tree. Water you citrus tree well after the application of Epsom salt.

When Not to Use Epsom Salt for Plants

Epsom salt can be a useful fertilizer in gardens under certain conditions. However, it’s not an all-around wonder plant fertilizer for all circumstances.

Don’t use Epsom salt instead of your normal fertilizer because it lacks important plant nutrients. You don’t need to use Epsom salt in soil that already has high magnesium levels. Epsom salt is not required for crops and flowering plants that grow fine in soil with low magnesium levels.

Epsom Salt for Lawns

Epsom salt is a beneficial product for lawn care due its magnesium and sulfur content that are essential for lush green lawn growth. Epsom salt contains magnesium, that benefits chlorophyll production, increases nutrient absorption, and helps keep lawn looking lush and healthy.

To use Epsom salt as a lawn fertilizer, add four tablespoons of Epsom salt to one gallon (3.8 liters) of water and use as a lawn fertilizer. Alternatively, sprinkle Epsom salt on top of the lawn and water it. Gardeners recommended using Epsom salt as lawn fertilizer during the spring.

However, as with using Epsom salt for plants, it’s only useful if your lawn has a magnesium deficiency. Before watering your turfgrass with an Epsom salt solution, it’s a good idea to do a soil nutrient test. If magnesium levels are low, or you notice that grass is yellowing, you could use Epsom salt for your lawn.

To avoid too much magnesium on your lawn and prevent leeching, use Epsom salt on lawns once a month during the growing season.

Liquid lawn fertilizers are another easy way to keep lawn looking lush and healthy with vibrant growth. You can also use organic lawn fertilizers to give grass essential nutrients.

Epsom Salt for Plants – Conclusion

Epsom salt for gardens can be an excellent soil amendment to resolve magnesium deficiencies. Magnesium is a vital component for healthy plants that is necessary for photosynthesis, nutrient absorption, and plant growth. However, Epsom salt for plants only works where magnesium deficiencies exist.

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