Can You Fertilize With Epsom Salt? (For Roses and More!)
If you’re new to gardening, the idea of using Epsom salt for plants might sound ludicrous. Can it be used for roses? Can it replace fertilizer? Only one of these things is correct!
Epsom salt is not a nutrient-complete fertilizer but it encourages flowering and fruiting in roses, orchids, peppers, and tomatoes. It can also treat soil and plant-based magnesium deficiencies. Feed roses 1 tbsp of Epsom salt in 1 gallon of water as a one-time solution to promote blooming.
The idea of fertilizing with Epsom salt has been around for decades. While there are some misunderstandings about its proper application, there are some advantages to using it for plants. Keep reading to learn more about each of these things!
Using Epsom Salt for Roses (Plus 3 Other Plants!)
What’s in a name? Shakespeare has mentioned at least 50 different plants in all of his plays, but the rose is the most memorable one of them all. Aside from roses, here are some other plants that will benefit from the use of Epsom salt.
Use Epsom salt to increase phosphorus intake and encourage flowering in roses. Epsom salt is best used as a supplemental fertilizer rather than a foliar spray, as this can burn foliage.
Epsom salt does not contain nitrogen, phosphorus, or potassium (NPK) and cannot be used as the main fertilizer for roses. So, how can Epsom salt help heavy-feeding rose plants produce more flower buds?
The added magnesium from the Epsom salt may help the roses take in more phosphorus.
Flower gardeners might have noticed how some commercial fertilizers have more phosphorus to help encourage more blooms.
The need for phosphorus is much higher on agricultural fields than in our usual gardens at home. But if your soil is old and overworked, Epsom salt may be useful in producing more roses!
For roses, mix 2 tablespoons of Epsom salt in the soil, or planting hole, and then water them once with an Epsom salt solution in the spring. The recipe for this solution is shared later on.
Remember, Epsom salt cannot replace fertilizer, so make sure to continue using your usual fertilizer alongside this. You don’t want to overuse the Epsom salt and cause a nutrient imbalance in the roses!
Epsom salt is commonly used for fertilizing and cultivating orchids. Orchids cannot grow in soil and will benefit from being fed Epsom salt 4 times a year.
Another beautiful flower would be the orchid, which is commonly given Epsom salt to help encourage growth.
Orchids are typically grown in sphagnum moss rather than in soil. This helps maintain the aeration that orchids need, but it contains little nutrients compared to soil.
Because of this, the orchids must receive their nutrients through other means.
Epsom salt can provide orchids with more magnesium and keep their leaves healthy throughout the year. To help the orchid establish itself before setting blooms, give the orchid Epsom salt 3–4 times a year and watch it bloom!
Are color-changing orchids normal? Find out in Why Has My Orchid Changed Color?
Use Epsom salt to provide pepper plants with additional magnesium to increase up to 25% pepper yield. While fruits are more abundant, these peppers are less nutritional.
A study in 2020 showed that extra magnesium increased pepper yields by a quarter!
Unfortunately, it wasn’t explained how much magnesium was used, but it’s safe to assume that Epsom salt can help you achieve similar results.
The drawback to this, however, is that it decreased concentrations of calcium and zinc in the plant, lowering its nutritional value as a result.
If you don’t mind this slight decrease in nutrition, Epsom salt can certainly be used to help encourage more fruits in pepper plants!
Read this article on how to harvest serrano peppers.
Tomatoes require more magnesium than other plants and can be fed Epsom salt as a supplemental fertilizer. Avoid using Epsom salt excessively as this can cause blossom end rot.
Tomatoes are known to face magnesium deficiencies quite frequently, so these plants will benefit from Epsom salt.
Also, they’re incredibly heavy feeders. So it’s important to use Epsom salt in small amounts to prevent and treat any magnesium deficiencies.
But remember, Epsom salt is never meant to replace regular fertilizers with nitrogen, phosphorus, and potassium entirely.
Doing so would only lead to blossom end rot, which can lower the overall yield.
If you’re hoping for better yields, check out the 12 highest-yield tomato varieties.
Several home gardeners have shared that Epsom salt caused tomatoes to grow thicker skin. Depending on how you wish to use these tomatoes, this may not be so appealing, so keep this in mind.
How to Use and Make Epsom Salt Fertilizer
Mix 1 tablespoon of Epsom salt in 1 gallon of water to treat plants and soil. Water the plants with the fertilizer twice during growing seasons. Application should only be with magnesium-deficient plants and soils, as it could otherwise cause leaf burn.
If your plants or soil are suffering from magnesium deficiency, Epsom salt can be an easy and quick fix!
To make an Epsom salt fertilizer, use 1–2 tablespoons of fragrance-free Epsom salt in 1 gallon (3.79 L) of water. Regardless of what type of fertilizer is used, less is always more.
Use the solution to water the affected plants twice in their growing season to allow the nutrients to reach the roots. The Epsom salt can also be mixed in with the soil or buried in the planting hole before planting.
Epsom salt can also be used to create foliar sprays. Only a tablespoon—or even less—will be necessary per 1 gallon of water. Foliar sprays can also be used for spot treatment on specific leaves showing a lack of magnesium.
But this method of spraying leaves is superficial, and will not solve what is likely an issue of the soil or general plant. Leaves exposed to extreme sun or temperatures over 90°F (32°C) will burn.
Adding unneeded magnesium can worsen whatever issues your plant is facing. So only use Epsom salt after you have taken a soil test to determine whether it is magnesium deficient.
Besides, plants are quite hardy. They have survived thousands of years without us and will probably continue to grow just fine without additional doses of Epsom salt.
What is Epsom Salt?
Epsom salt is a water-soluble mineral containing magnesium, sulfur, and oxygen. It is different from the traditional table salt. Commonly, Epsom salt is used to provide roses with micronutrients such as magnesium and sulfur to encourage the roses to take in more phosphorus for flowering.
The Epsom salt was found by accident in the early 1600s, in an England town named Epsom. After evaporating the bitter spring water, they were left with a mineral powder high in magnesium sulfate.
Epsom salt has been used in baths for years and, as a result, is also sometimes referred to as “bath salts.” So how exactly did Epsom salt become so popular in the gardening world, and why?
Epsom salt contains 3 different elements: magnesium, sulfur, and oxygen. Magnesium and sulfur are some of the many micro-nutrients plants need to grow and produce chlorophyll.
These nutrients are vital and have multiple key roles in plants. Because of this, some home gardeners swear by using Epsom salt, even saying it can treat numerous things.
Some people believe that Epsom salt can be used for roses, is environmentally friendly, can be used as primary fertilizer, prevents blossom end rot, and fights off pests.
But is there any truth to these claims? After talking with some home gardeners and experts, here are the current conclusions I will be sharing with you today!
2 Benefits of Using Epsom Salt For Plants
Epsom salt can be used to treat magnesium deficiency in plants and replenish old soil.
It might seem strange, but there are some advantages to using Epsom salt treatments or fertilizer for plants. Let’s go over them!
1. Treat Magnesium Deficiency
Epsom salt contains high amounts of magnesium and can be used to correct magnesium deficiencies in crops. Most of the soil in North America already contains adequate quantities of magnesium, but the deficiency is also common in plants.
The most effective way to use Epsom salt in the garden is to use it to treat plants with magnesium deficiency.
Magnesium doesn’t just aid in absorbing other nutrients. It also acts as part of the green, light-catching pigments in plants called chlorophyll. In other words, it also has a crucial role in photosynthesis!
Without adequate magnesium, the plants will have stunted growth and veiny yellow leaves. These symptoms tend to appear on the lower leaves first.
So although a lack of magnesium won’t kill the plant, it can reduce overall yield and ultimately leave it in a more vulnerable state.
Since Epsom salt is high in magnesium, it will assist the plant in producing more chlorophyll. Over time, it will help “perk up” the plant, so to speak, and help make the foliage healthy and green again.
Magnesium deficiencies in soil are extremely unlikely for those in North America. If you suspect the soil is deprived of magnesium, it’s best to take a soil test for confirmation.
2. Replenish Old Soil
Nutrient-depleted soil and substrates can be amended with small quantities of Epsom salt to increase oxygen, magnesium, and sulfur content. However, it cannot provide other nutrients such as nitrogen or potassium.
Soil nutrients can be lost in myriad ways. It can leach out with water, get destroyed by extreme sun exposure, used up by plants, or simply be lost over time.
While commercial farms are more likely to struggle with overworked soil, it can be common for home gardeners—especially ones who recycle the same soil.
Read more about old soil in this article Does Potting Soil Go Bad?
It’s also common nowadays for plant owners to use other substrates aside from soil. Peat, for example, can retain up to 20 times its weight in moisture. However, this substrate contains very few nutrients and may not be suitable for optimum plant growth.
If compost and fertilizers are not available, Epsom salt can help reintroduce nutrients to these soils and substrates.
Learn the differences between Liquid vs Granular Fertilizer.
However, it is important to remind you that Epsom salt contains nothing else aside from magnesium and sulfur and will not replace any other elements.
4 Cons of Using Epsom Salt For Plants
The 4 cons of using Epsom salt for plants are that it cannot prevent blossom end rot, fight pests, it is not a substitute for regular fertilizer, and is not environmentally friendly.
Now that we’ve gone over the true benefits of using Epsom salt, are there any drawbacks? Unfortunately, the answer is: Yes.
It’s essential to know that there is no miracle solution for our gardening problems, and Epsom salt certainly should not be used as such.
Here are some of the cons of using Epsom salt and the myths that surround it.
1. Cannot Prevent Blossom End Rot
Epsom salt does not contain calcium and cannot be used to prevent blossom end rot. The active magnesium in Epsom salt will inhibit plants from absorbing calcium and can ultimately increase the risk of blossom end rot.
Epsom salt has supposedly been used for years to prevent blossom end rot, but does it work? First, let’s understand how blossom end rot develops in plants.
Blossom end rot is a type of plant disease commonly found in tomatoes and peppers, and is caused by a lack of calcium. Some say that Epsom salt can prevent blossom end rot from affecting their crops.
Epsom salt does not contain any calcium. Contrary to popular belief, it can even increase the chances of blossom end rot.
Agricultural research has shown that magnesium is a direct competitor of calcium and will prevent the plant from absorbing it. This will further deprive the plant of its much-needed calcium and can ultimately cause blossom end rot.
It is more likely that plant owners using Epsom salt just became more consistent with their watering as they were feeding their plants. Regular watering is the number one way to help the plant take in more calcium and avoid rot.
2. Cannot Fight Off Pests
The magnesium and sulfur in Epsom salt do not have any effect on garden pests and cannot be used as an effective pesticide.
Another common benefit that Epsom salt is said to have is that it eliminates pests like voles and slugs. Supposedly, this is due to its salt content or sodium.
This misunderstanding most likely took place because of the word “salt” in Epsom salt.
Before we proceed, it’s important to remind you that Epsom salt does not contain any sodium. It is a different compound from table salt.
Additionally, magnesium is not a common or key ingredient in many natural and commercial pesticides nowadays.
Unfortunately, magnesium does not have any effect on common garden pests like thrips or aphids. Moreover, pests have individual life-cycles and systems. Therefore, they require different methods for elimination.
Read about the 25 pests that eat tomato plants.
Furthermore, most animal pests tend to ignore plants that are low in magnesium. They are more likely to eat magnesium-rich ones. Thus, the application of Epsom salt may not be too helpful when it comes to deterring or getting rid of pests.
For a natural and efficient pesticide, take a look at neem oil.
3. Not a Substitute for Fertilizer
Although the magnesium in Epsom salt is important for plants, it does not provide other key nutrients like potassium for plant growth. Excessive amounts of magnesium can also inhibit the absorption of other nutrients and further harm the plant.
Fun fact: The soil on Mars, or Martian soil, is confirmed to have an abundance of magnesium, making it challenging to host plant life.
While this may not be a problem for those of you living on Earth, it is an excellent way to show how too much magnesium can hinder plant growth.
Read our article to find out Can Plants Grow On The Moon?
Epsom salt does not contain essential nutrients such as Nitrogen, Potassium, and Phosphorus (NPK). Because of this, it should not be used as a primary fertilizer.
Nitrogen is key for producing more foliage, while potassium aids the general health of the plant and helps it fight disease. Phosphorus is important for flower bulbs and root growth.
To achieve optimum plant health, each of these nutrients must be provided. Too much Epsom salt can lead to excessive amounts of magnesium and block calcium.
Additionally, because magnesium allows for more phosphorus, it’s more likely for phosphorus to build up and prevent the plant from absorbing other nutrients, like iron.
It is all a very delicate balance, and too much or too little of just one nutrient can trigger a domino effect! So unless you’re certain your soil or plant is lacking magnesium and have taken a test, Epsom salt is pointless.
4. Not Environmentally Friendly
Epsom salt is not eco-friendly and will run down the soil to pollute underground water systems. This Epsom salt water runoff can be harmful to the environment by contaminating water.
Another source of uncertainty surrounding Epsom salt is how it apparently cannot be overused. It is claimed that using Epsom salt is eco-friendly and can easily be washed away in the soil.
This may sound harmless at first. Indeed, Epsom salt is water-soluble and does not stay in the soil; these things are true.
However, these minerals will run straight through the soil and pollute the delicate groundwater systems underneath. Groundwater is a main source of freshwater for millions across the globe and is becoming harder to find.
Thus, it can be suggested that Epsom salt is not eco-friendly and can be damaging to the environment. It might not be harmful to today’s gardens, but over time this could disturb what’s left of our limited resources and ecosystems.
Can Epsom salt be used for grass?
While Epsom salt can be used to produce more chlorophyll which can help grass look greener, this will only benefit grass that is being grown in magnesium-deficient soil. Epsom salt cannot be used to treat any issues other than a lack of magnesium.
Is Epsom salt plant food?
Epsom salt is a mineral that contains magnesium, sulfur, and oxygen and can be used as a supplemental source of nutrients for plants. However, it should not be used frequently or in place of fertilizers with nitrogen, potassium, and phosphorus (NPK).
Can I sprinkle Epsom salt around plants?
Epsom salt can be sprinkled in small doses for magnesium-deficient plants. Do not use more than 2 tablespoons for a single plant, as this can lead to excess magnesium and prevent the plant from absorbing calcium. This lack of calcium can lead to blossom end rot in tomatoes.
Summary of Using Epsom Salt for Plants
Epsom salt is a good source of magnesium and sulfur, both of which are vital nutrients required for photosynthesis and optimum plant growth. It can be used to treat magnesium-deficiencies in soils and plants, and also help revive old soil.
The magnesium in Epsom salt can aid roses produce more flowers, can increase pepper yield by 25%, and can also be used as a supplemental fertilizer for orchids and tomatoes. Avoid applying excess Epsom salt and magnesium by only using 1–2 tablespoons of Epsom salt with 1 gallon of water to feed plants once or twice as they grow.
But because Epsom salt does not contain any nitrogen, potassium, or phosphorus (NPK), it cannot replace regular fertilizers. Additionally, Epsom salt cannot be used to prevent blossom end rot, fight pests, and is not environmentally friendly.
- “Epsom salts and veggies” by Kelly Feehan in University of Nebraska
- “Coffee grounds, eggshells and Epsom salts in the home garden” by Anne Sawyer in University of Minnesota
- “Magnesium Important to Vegetable Growth” by Joe Kemble and Jeremy Pickens in Alabama and Auburn Universities
- “Magnesium for crop production” by Daniel E. Kaiser and Carl J. Rosen in University of Minnesota
- “Monitoring and Correcting Magnesium Deficiency in High Tunnels” by n/a in South Dakota State University
- “Essential Elements for Plant Growth” by Phillip Barak in University of Wisconsin
- “Soils, Plant Nutrition and Nutrient Management” by Manjula V. Nathan in University of Missouri