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Is Epsom Salt Good For Plants?

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Over the years I have used Epsom salt on my plants as a way to boost their strength and to provide nutrients when plants are subjected to stress. In fact, I have even recommended this to other gardeners as a way of treating plants. Recently I was asked Is Epsom salt is good for plants or is it just a myth?

Is Epsom salt good for plants? Yes, Epsom salt is an ideal product to use for your plants. We all know Plants need Magnesium to be healthy and Epsom salt is made from Magnesium Sulfate and Sulfur. This is absorbed by the plant’s root system making them stronger and much more resistant to pests and diseases. It increases growth and produces larger vegetables and blooms.

Do I need to add Epsom salt to my plants?

Epsom salt is not required if your soil has sufficient magnesium. The only real way to know if this is the case is to have your soil tested. There are various ways in which to test the soil. A simple soil testing kit could be purchased and this will give you an idea of whether there is enough magnesium in your soil.

To be more precise though, you could take a soil sample from various sections of your garden and send it to a soil testing lab. There are various companies online that can perform this task for you. Living in the UK I use a company called Lancrop Laboratories. These will provide you with a complete soil analysis.

What plants can you put Epsom salt on?

You can use Epsom salt with pretty much any plant providing that your soil does not have it in sufficient quantities. As plants require magnesium for sustained growth, Epsom salt will provide this via the root system. It is water-soluble so is readily available to the plants.

This will boost the plant’s immune system, making them much stronger and healthier. As a side benefit, this allows the plants to fend off disease and pests and produce a much larger yield of vegetables, fruits, or flowers.

Can too much Epsom salt hurt plants?

Yes, too many Epsom salts can hurt your plants. This is caused when you overload the soil. Saturating it with magnesium. As Magnesium is prioritized by plants when taking up nutrients, this can nutrient lock your plants.

What this means is that the plant will take up so much magnesium it is unable to take in other needed nutrients such as boron, sulfur, and even calcium. This can be a big issue with tomatoes, peppers, and eggplants getting blossom end rot. Gardeners rightly think that their plants are not getting enough calcium with BER. (Blossom End Rot).

This is the case, however, it is not because there is not enough calcium in the soil. It is because the plant is nutrient locked to magnesium as the gardener applied too many Epsom salts to the ground.

How do I apply Epsom Salt to my plants?

Epsom Salt is water-soluble. It comes in a crystal form very much like table salt, only a little larger in size. There are three ways in which to apply Epsom salt to your plants.

  1. At planting time
  2. As a plant drench
  3. As a foliar spray

At Planting Time

If you find your soils are lacking magnesium at the time of planting, you can add the Epsom salts in crystal form to the planting hole. Apply 1 to 2 teaspoons to the excavated soil and mix this in. Over the next few weeks, this will dissolve providing Magnesium to your plants.

As A Plant Drench

You may find that plants show the signs and symptoms of magnesium deficiency throughout the growing season. You can help them along by watering the plants as a drench. Simply mix up 1 tablespoon of Epsom salt into 1 gallon of water.

Allow this to dissolve and completely drench the plant from head to foot. This will allow all sections of the plant to uptake the Epsom salt quickly.

As A Foliar Feed

Epsom salt can be used as a foliar feed too. Mix 1 tablespoon of salt to 1 gallon of water and spray the leaves. Both the top and underneath. Do this in the morning when the plant is uptaking water and you will get better absorption.

By foliar spraying in the morning, It will allow the plant’s leaves to dry off preventing them from sitting wet overnight, which can attract pests like slugs and diseases like blight or powdery mildew.

How do you use Epsom salts in potted plants?

Potted plants are where Epsom salt can really help. The nutrients in a pot are quickly used up by the plants and Magnesium is one of the first to go. By applying Epsom salt during watering once a month should alleviate these issues. Mix as making a drench like I explained above and simply use it to water the plants as normal instead of plain water. Be mindful of salt build-up once your plants look green and healthy again cease applying the Epsom salt.

Is Epsom Salt Good for Houseplants?

Yes, Use Epsom salt the same as you would for potted plants by making the dose exactly the same. Houseplants may also be lacking with light levels. It is important to understand why your plant looks sickly before applying the Epsom salt. Do not overload the soil or you will cause nutrient lockup when It may not have been a magnesium deficiency.

Is Epsom Salt Good For Roses?

Epsom salt can be used with any plant that has a magnesium deficiency. However, despite the myths that Epsom salt will create better blooms on roses, this is only ever the case if there is a magnesium deficiency in the soil. If there is sufficient magnesium in the soil, no benefit will be seen by adding additional Epsom salt. In fact, you could possibly do more harm to the plant if you over-load the soil.

Are there negative effects to Epsom Salts when growing plants?

It has become common practice in gardening, especially well-meaning gardeners that if your plants are sick apply Epsom salt. Epsom salt is not a miracle cure. It is becoming a habit of some gardeners to apply it liberally over their entire garden.

This thinking should be avoided at all costs. Epsom salt is salt after all. It can build up in the soil and nutrient lock your soils. Gardeners usually see their plants looking sick and visit a forum where well-meaning gardeners will tell them to use Epsom salt without really understanding the problem.

Salt is bad if allowed to build up in your soil. It will kill the soil life which for any gardener is the most important factor in gardening. With good soil, you can grow anything. Using Epsom salt in this way without first identifying the real cause is very dangerous. IT WILL DO MORE HARM THAN GOOD!

Can Epsom salt be used to fertilise my plants?

Epsom salt is not a fertiliser. It cannot be used to feed your plants. It will only allow you to replenish soils that have inadequate magnesium to make that available for your plants. Under no circumstances should Epsom salt be thought of as a feed for your plants.

As discussed there is only two real cause of Magnesium deficiency in plants. They are:

  1. Lack of soil Magnesium
  2. Imposed deficiency

Lack of soil Magnesium

This is where gardeners have extensively cropped an area of the garden and are not allowed the appropriate time for the ground to recover. Or have grown the same heavy magnesium required crop types over and over in the same soil depleting it.

Imposed Deficiency

This is where the well-meaning or inexperienced gardener has nutrient-locked their soil. As discussed earlier, If you wrongly thought your plants were lacking in magnesium due to looking sickly. Then you applied large quantities of magnesium in the thought that it was deficient but wasn’t. You can lock the nutrients in the soil so that the plants can only take up magnesium.

This can really be the danger of using too much Epsom salt in the garden. Without ascertaining the real cause of sick plants, you cannot assume its magnesium deficiency and just apply liberally. You MUST TEST your soil to be sure.


Epsom salt is great for helping with maintaining plant health and the levels of magnesium in your soils. However, It should not be just added for the sake of adding Epsom salt thinking it will help. This thinking will have huge negative impacts on your plants.

Epsom salt certainly has a place in the garden. But it must be used wisely, Do not just listen to advice about using it. Test your soil before adding it to see if, in fact, it is deficient at all.

Then and only then can you make better choices as to whether your garden and plants require Epsom salt. You may find after testing that you do not have a deficiency which can then lead you into looking into other possible causes of the sick plants.

Don’t make them sicker by just adding it. Be 100% sure it is required. Keep your soil health good and the plants will look after themselves

I hope this has cleared up whether Epsom salt is good for plants, You now know exactly how to use it, and more importantly when, and when not to use it.

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