How to Use Epsom Salt on Houseplants?

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Epsom salt has many household uses, one of which includes using it on plants. But is it any good? And should you use it on houseplants?

Using Epsom salt in the garden isn’t a novelty or a fade. The practice has actually been around for generations. The rationale behind using Epsom salt on plants is to encourage blooming and plant growth.

Does it work?

It seems that this old wife’s tale isn’t just a tale and Epsom salt added to plants can be beneficial under certain conditions.

What benefits can you expect, and which plants stand to gain the most benefits? I answer all these questions and more below.

Benefits of Using Epsom Salt for Your Plants

Epsom salt or magnesium-sulfate compound (MgSO4) is a common item in many households. Added to plants, it is said to help in the following areas:

– Improves Blooming

Epsom salt added to plants will boost blooming and fruit production. Some say it will even improve the flavor of veggies and fruit.

– Increases Nutrient Absorption

Magnesium-sulfate is also proven to increase the plant’s absorption capabilities of other essential nutrients including nitrogen and phosphorus.

– Improves Foliage Vibrancy

Plants grown in soil with magnesium deficiency will produce less vibrant leaves. The compound in Epsom salt helps in the creation of chlorophyll and produces more vibrant foliage.

– Keeps Pests Away

This common household item can help in keeping pesky pests away if it’s diluted in water and sprayed onto the leaves of plants.

Sprinkled over the soil, it will keep slugs and snails away and prevent them from munching on the leaves of your plants or veggies.

Which Plants Like Epsom Salt?

Plants that are grown in magnesium deficient soil can benefit from Epsom salt. But some plants crave more magnesium than others, and as such, satisfying that crave is greatly beneficial to them.

Plants that require magnesium at a higher degree include tomatoes, peppers and roses. Other plants such as azaleas or rhododendrons will also benefit from Epsom salt.

Epsom salt is either added to the water, sprinkled onto the soil, worked into the soil, or as a foliar spray, depending on what you’re trying to achieve.

It’s important not to use Epsom salt as a substitute for a fertilizer. While Epsom salt provides magnesium to plants, it doesn’t provide nitrogen, phosphorus or potassium (N-P-K).

Therefore, you can use Epsom salt in addition to the plant fertilizer designed for your plants but not in lieu of it.

Likewise, just because a soil is deficient in magnesium, it doesn’t mean all plants crave it and that you need to make up for the lack of magnesium.

Some vegetables and plants can simply grow happily in magnesium deficient soil as well.

Can Too Much Epsom Salt Hurt Your Plants?

As with any fertilizer, even a balanced one, you need to be careful about not adding too much Epsom salt to your soil.

While it’s soluble in water and washes away, it can still create an imbalance in the chemistry of the soil.

At high doses, Epsom salt can cause soil toxicity, blossom end rot, potassium deficiency, all of which are detrimental to your plant.

Just because you’ve determined that your soil or plant is magnesium deficient, adding Epsom salt may not solve the problem. Soils that are high in phosphorus can interfere with the plant’s ability to uptake magnesium.

If you add Epsom salt to a soil that’s high in phosphorus, you won’t see any improvement. Only by testing your soil can you adequately determine the reason behind a suspected magnesium deficiency in plants.

In conclusion, using Epsom salt in excess or using it when the soil is high in phosphorus can create imbalances that will affect the health of your plants.

Can You Use Epsom Salt for Indoor Plants?

Magnesium is not a nutrient that’s required by indoor plants at a significant rate. Therefore, plants that otherwise don’t crave magnesium or the soil of which is not deficient in magnesium, aren’t likely to drive much benefit from Epsom salt added to their soil.

Adding Epsom salt to small potted plants also runs the risk of making dosage mistakes and using too much of it.

That said, if you can ascertain for sure that your potted plant is suffering from magnesium deficiency, you can try adding a small amount of Epsom salt diluted in water to see if there’s an improvement.

Will Epsom Salt Kill Aquarium Plants?

Apart from its household use and use as plant fertilizer, Epsom salt is also used in aquariums. It’s commonly used as a way to ease constipation, bloating and water retention issues in fish.

If you also have plants in your aquarium, you may be worried that Epsom salt can kill or otherwise damage your aquarium plants.

At the concentrations usually used in aquariums, Epsom salt is safe for your aquarium plants. Moreover, if fish are treated with Epsom salt, a water change is usually performed after 24 hours.

That said, Epsom salt does increase the general hardness of the water, which can have implications both for the health of your fish and the health of your aquarium plants.

Dosage is important, so don’t add more than it’s recommended for the size of your tank and both your fish and aquarium plants should be fine.

Wrapping Up

Epsom salt is a cheap and efficient way to make up for any magnesium deficiencies in your outdoor or indoor plants. Plus, it’s something that most of us already have in the cupboard.

If you plan on using Epsom salt, make sure you do so at the correct concentrations. You don’t want to use too much and cause imbalances that may hurt your plants.

Also, don’t use Epsom salt as a substitute for fertilizer. Epsom salt does not contain any other nutrients than magnesium sulfate. And plants don’t even need that much of it.

Always supplement your plant’s nutritional needs with a balanced fertilizer instead and use Epsom salt only if your plants are magnesium deficient.

Updated: October 12, 2020

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