Epsom Salt for Pepper Plants: More Harmful Than Helpful?

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A bag of Epsom salt for pepper plants in the garden.

You’ve heard the gardening life hack: Use Epsom salt for pepper plants to get explosive growth and production. I’ve even done it myself a few times!

But is it a good idea? I thought so for a while, but the more I learned about the chemical makeup of Epsom salt and what it can do to the soil, I started to have second thoughts. Also, I didn’t notice any significant difference in my pepper’s growth. So I’ve now come to the conclusion that Epsom salt is not the garden cure-all it’s said to be.

In this post, I’ll be sharing what I’ve learned and experienced in applying Epsom salt to plants, along with what it actually is. There are a few instances where Epsom salt can be safe, so we’ll also take a look at how to use it then.

Let’s get started!

Key Points:

  • Epsom salt was discovered in the 17th century and consists of magnesium sulfate.
  • Magnesium and sulfur are two vital elements for plant growth and development.
  • Too much magnesium in the soil can cause imbalances that interfere with pepper plants’ ability to absorb other critical nutrients.
  • Epsom salt is not a complete pepper fertilizer and may cause magnesium toxicity in the garden soil.
  • If it’s used carefully, Epsom salt may be safe to use in limited circumstances, but there are better ways to fertilize and address nutrient deficiencies.

What is Epsom Salt?

Epsom salt gets its name from the English town of Epsom. According to Eco Bath London, a cow farmer named Henry Wicker discovered Epsom salts in 1618. Wicker noticed that his cows would not drink the water that pooled in the area, but cuts and scrapes on the cow’s legs healed much faster when they spent time standing in or wading through the water.

Being the enterprising man that he was, Wicker did more experimenting in the Espom waters, finding that the water revitalized the skin, relieved constipation, and seemingly boosted health. Eventually, the town became well-known as a healing destination, and people flocked to the area to soak in the waters.

Even though the exact mineral makeup wouldn’t be known for some time, the waters in Epsom were rich in magnesium sulfate, a blend of magnesium and sulfur elements. Those minerals were later gathered up, packaged, and sold far and wide as Epsom salt.

A closeup of the ingredient profile on a bag of Epsom salt.

It was obviously helpful for people and animals, but does that mean Epsom salt is good for plants too? Let’s take a closer look.

What Does Magnesium Do for Pepper Plants?

Magnesium is classified as a secondary macronutrient, meaning that plants need it for basic life functions but in a lower amount than primary macronutrients (nitrogen, phosphorous, and potassium).

Scientific studies have that magnesium has several vital functions within a plant, including these:

  • Assists in transporting and metabolizing phosphorous
  • Protein production
  • Chlorophyll production
  • Enzyme action

What Does Sulfate Do for Pepper Plants?

Sulfur, in the form of sulfate, is another essential secondary macronutrient. It helps produce healthy proteins and certain hormones, which act as a messenger system within the plant.

According to Premier-Tech Horticulture, sulfur is pretty easy to deplete in the soil, whether from washing away with heavy rain or leaching out of the soil.

Is Epsom Salt Good for Peppers?

Both magnesium and sulfur are critical elements that all plants, including peppers, need to regulate their biological functions and grow. So it makes sense to give some extra mineral support to your plants, and since it has many good uses for humans, surely your garden can benefit too, right?

The conclusion I’ve come to is that Epsom salt could be helpful in certain rare circumstances, but it’s not a wonder drug that’s the key to a thriving garden. I’m not aware of a single situation where Epsom salt is the only solution, or even the best one.

In fact, in most circumstances, Epsom salt has the potential to cause more harm than good- and there’s a lot to why that is. In this section, I’ll break it down a little more.

Why is Epsom Salt Dangerous in the Garden?

Epsom salt is almost purely magnesium sulfate, and while that’s a vital element for plant health, it becomes toxic in excessive amounts.

Having too much magnesium creates an imbalance that can keep your plants from absorbing calcium and potassium, which are both critical elements themselves. When this happens, your pepper plants can develop discolored leaves, poor fruit production, and slow or non-existent growth.

While having a bit of extra magnesium in the soil isn’t likely to cause problems right away, you might start to notice issues if you use Epsom salt regularly. The bad part is that there’s no reliable way to measure exactly how much magnesium you’re adding to the soil and what the current overall levels are. You’re basically guessing and keeping your fingers crossed- and that’s not a sustainable way to keep a garden healthy and productive.

A gardener holds a handful of Epsom salt granules near a banana pepper plant in the garden.
Is this a good idea?

When is Epsom Salt Good for Pepper Plants?

The only time when Epsom salt is a good idea to give your peppers is if a laboratory soil test confirms that your soil is deficient in magnesium. And that’s an unlikely scenario for the average home gardener.

Typically, magnesium is pretty abundant in the soil- it’s released naturally from many common minerals breaking down. In some areas of the country, magnesium is already very high. Most of the time, the only soil that is truly magnesium-depleted is agricultural land that’s aggressively farmed.

But even if a soil test shows low magnesium, Epsom salt probably isn’t the magic bullet.

As I already stated, too much magnesium can cause an effective lack of calcium. You should apply the two elements together to unleash their full potential and avoid throwing off the overall soil nutrient profile. That’s why most fertilizers formulated to deliver either magnesium or calcium come as a cal/mag combination- that way, your plants get what they need in the right balance.

Epsom salt only supplies magnesium, so if you’re using it in a large dose or regularly, you’ll also need a calcium supplement. But unless you’ve got organic chemistry equipment at home, you’ll likely be guessing at the right amounts of each one.

And what about the sulfate component? It’s necessary for plant health, but there are better ways to boost sulfate than using Epsom salt- and it’s actually pretty easy. Compost is one of the best natural sulfate sources since decomposing organic material is rich in sulfate. Another way to add sulfur is to use cover crops in the off-season, then chop them up and let them decompose in the soil. There are also sulfur soil additives you can purchase.

So I don’t recommend using Epsom salt for its sulfate component.

In short, there are lots of better pepper plant fertilizers out there that supply safe amounts of magnesium and sulfur while avoiding the imbalances that can cause problems.

How to Use Epsom Salt for Pepper Plants: 3 Ways

So Epsom salt isn’t the answer to all your garden woes like many people say. The flip side, though, is that it probably won’t hurt your plants either; as long as you apply it sparingly, it would likely take quite a while to build the magnesium to dangerous levels.

That was my experience with Epsom salt on peppers- I used it as a foliar spray a few times over the growing season one year, and I didn’t run into any major problems.

So if your gardening friends are telling you the wonders of Epsom salt and you want to give it a try too, here are my suggestions for doing it safely.

 1. Foliar Spray

Foliar sprays are a great way to quickly deliver nutrients to your plants, and that’s especially true with Epsom salts since plants readily absorb magnesium through their leaves. This is the method I’ve used before to apply Epsom salt to pepper plants.

As far as I’ve learned through my research, plants do not release magnesium into the soil, so a foliar application should be a safe way to keep excess from getting into the soil.

I mixed up a bottle of Epsom salt water in a spray bottle and used it a few times on my garden veggies, adding 2 tablespoons of Epsom salt to a gallon of water.

How to apply foliar spray: I always try to time any foliar spray applications for the evening hours, although the early morning hours are another good time. Essentially, what you want to avoid is applying during or just before the prime sun exposure of the day- typically 10AM to about 7PM. You don’t want moisture on the leaves during that time since the sun’s rays can severely scorch leaf tissue.

As for seasonality, I recommend waiting until the plants are at least a couple of months old and it’s been a few weeks after transplanting your peppers into their permanent home.

2. Diluted in Water

Epsom salt is readily water soluble, and you can dissolve it in a watering can and apply it as a normal watering.

I learned a lot from this video from The Rusted Garden- you can give it a watch here:

How to give diluted Epsom salt: Use about 1 tablespoon of Epsom salt for 1 gallon of water. Give your pepper plants diluted Epsom salt water any time of the day you would normally do your watering. When judging by plant age, I recommend waiting until about mid-season to give a good watering, and that should be more than enough for the entire season.

3. As a Soil Additive at Planting

Magnesium plays a key role in seed germination, and research studies show that low magnesium levels can cause poor germination rates.

How to use Epsom salt at planting: I’ve never personally used Epsom salt when I plant my pepper seeds, lots of other gardeners do and report good success. The usual recommendation is 1-2 tablespoons of Epsom salt in every seed-tray cell, which actually seems like a lot to me. If I was going to try it, I’d use 1 tablespoon at the very maximum.

If you live in a warm climate and can direct-sow your pepper seeds in the ground, I’d still cap it to 1 tablespoon of Epsom salt per seed hole.

Frequently Asked Questions about Epsom Salt for Pepper Plants

Raising the soil magnesium level is a real danger with Epsom salt, especially when applied full-strength and in a large dose, as is very common when sprinkling granules. The safer application route is diluted in water and used as a normal watering or as a foliar spray.

Yes, Epsom salt can cause magnesium toxicity that interferes with your pepper plants absorbing and processing other vital nutrients.

Compost is the best choice for homemade pepper plant fertilizing. You can make compost at home in a compost bin or pile, and worm composting systems are another outstanding option.

Final Thoughts

To sum it up, using Epsom salt for pepper plants isn’t the worst thing you could do, but it definitely isn’t the best either. There are many better ways to supply your plants with the nutrients they need with a more complete nutrient profile and in the right amounts than guessing with Epsom salt.

So if you’ve never used Epsom salt in your garden, you’re not missing out. And if you do decide to give it a try for yourself, apply it very sparingly and keep your expectations for results low.

I’d love to hear from you! Have I covered all your questions about using Epsom salt peppers, or are there still things you’re wondering about? Or maybe you’ve got some firsthand experience with Epsom salt that you’d like to share. Either way, your question or answer might be just what someone else is wondering about, so please let us know in the comments!

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