You've heard about using Epsom salts for plants in your garden. Yes, the same stuff you’ve seen at the drugstore. Those bath salts intended for soaking your pain away have a claim to fame in the garden, too.
It seems counterintuitive, doesn't it? Salt? In the garden?
Magnesium and sulfur are two trace minerals required by plants to survive and thrive. The idea is that since plants need these nutrients to live, using Epsom salts is a way to help your garden flourish. More is always better, isn't it?
But is it the miracle amendment people make it out to be?
We’ll explore the numerous claims surrounding magnesium sulfate and why you may not want to rely on it to solve your plant woes.
Claims About Epsom Salts for Plants
Good old table salt might be bad for your plants, but Epsom salt, also known as magnesium sulfate, has an entirely different reputation in the gardening community.
The supposed benefits of using Epsom salts for plants are numerous. You can easily find it at the pharmacy, it's inexpensive, and you can apply it easily.
Do a quick Google search, and you'll see an overwhelming amount of content that seems to point to Epsom salts as a miracle solution for everything from gardening to illness.
As a runner, I’m well aware of the claim that soaking in an Epsom salt bath will cure all aches and pains. Honestly, soaking in any hot water does wonders for a body that’s been put through the ringer.
I’ve tried an Epsom soak, and while it’s a lovely self-care ritual, I’m skeptical that it’s any different from enjoying a soak with a colorful bath bomb.
The same is true when it comes to using magnesium sulfate in the garden. Epsom salts have gained a stellar reputation thanks to word of mouth.
But while I’ve received some great growing tips through the grapevine, not every piece of advice is golden. Take miracle claims with a grain of salt 😉
So what do people say about Epsom salts? Here are some of the things people claim this amendment can do:
- Deter pesky pests from insects to small mammals
- Act as a nutrient supplement
- Produce lush plant life
- Increase flowering rate
- Decrease instances of disease
- Increase germination rates
Gardeners love a cure-all. There's something that can help in all corners of the garden and targets many common problems? Sign me up! Scientific evidence on the use of Epsom salts in the garden, however, is limited at best.
In reality, while magnesium sulfate is highly soluble, it’s entirely possible for it to become a contaminant. And while it’s an attractive option for gardeners on a budget, it doesn’t provide the value it claims to offer.
Why It’s Not a Gardener’s Miracle Tool
Plants have an appetite just like humans do. They require nutrients to grow and flourish. However, plants don't need magnesium and sulfur in large doses. They’re necessary for growth, but it’s unlikely that your small plot of vegetables or entry-way rose bush is deficient in either nutrient.
Besides, the only way to know whether your plants are missing a specific nutrient or trace mineral is to get your soil tested. Adding magnesium sulfate to your garden willy-nilly isn’t a good idea. In addition, organic amendments such as mulch or compost typically provide plants with all the Mg and Su they need to thrive.
What about the claims surrounding pest reduction? These claims, as well as those regarding disease eradication, are overblown and not scientifically accurate.
While adding Epsom salts seems like an attractive quick-fix, there’s little proof that the stuff can prevent infestations. Small mammals are unlikely to be deterred by the stuff, so don’t expect rabbits to quit munching on your carrots.
Adding Epsom salt in small quantities may not have a significant effect on the nutrient composition of your soil, but excess magnesium can readily leach out from the earth and contaminate nearby water supplies. Essentially, it becomes a pollutant. Similarly, spraying a diluted Epsom salt solution onto plant leaves can cause leaf burn, which in turn can leave your plants vulnerable to disease and actually attract pests to your garden.
By the way, there’s also no concrete evidence that shows that Epsom salts for plants aid in germination. Seeds need the right conditions to sprout, not a handful of magnesium sulfate. If by chance a packet of seeds seems to germinate more successfully, it’s not because of Epsom salt.
It’s probably because the seeds are fresh, receive plenty of full-spectrum light, are grown in the right temperature conditions, and get adequate moisture. This and many of the other claims surrounding Epsom salts are slightly misleading since they infer that adding it will improve flowering rates, growth rate, etc.
Can it help with nutrient deficiencies?
The reality is that if your plants are indeed deficient, reversing the deficiency will no doubt result in measurable growth, but Epsom salts may not be the best way to get an extra boost.
Think of it like this. Your car won't run if it doesn't have gas. Fill up the tank and off you go. Overfilling the tank, however, doesn't offer any extra advantage and can cause problems.
If your garden is not deficient in either magnesium or sulfur, adding Epsom salts probably won't have much of an effect and may instead be detrimental. It's a waste of money and effort. It likely won't increase the growth rate or produce more flowers than usual.
If you do notice a difference from year to year or plant to plant, you may want to blame it on environmental factors or other actions you've taken in the garden. It's highly unlikely to be the magnesium sulfate you've added.
Epsom salts are also often recommended for use with tomatoes and peppers because it can prevent diseases like blossom end rot.
Here’s the kicker, adding magnesium when there is no real deficiency can cause the disease in question by limiting a plant’s ability to absorb nutrients such as calcium. A lack of calcium, by the way, is the real culprit of blossom end rot.
In fact, magnesium sulfate, while often marketed and described as a way to “feed” plants, is anything but a significant nutrient source. More important are nitrogen, potassium, and phosphate (NPK). Don’t be fooled, Epsom salt has an NPK value of 0-0-0. It's not a significant nutrient source.
What if my plants are indeed deficient in either nutrient?
Adding Epsom salts may not be the answer. First, get a soil test. It will provide you with the information you need to address the problem. When dealing with any suspected soil deficiency, a soil test is a must to ensure you don’t mess with the nutrient composition of the soil.
It’s possible that if your soil is missing or has too much of another nutrient, it may prevent absorption of magnesium. In such a case, adding a magnesium amendment would not reverse the ill-effects. You would need to address the issue with the other nutrient first.
In any case, adding Epsom salts to plants in your garden is not a surefire way to deal with a deficiency of magnesium or sulfur. The highly soluble nature of this mineral means that it’s not a good permanent solution for fixing a nutrient imbalance.
There is some evidence that Epsom salts can give your plants a quick boost of magnesium if it is deficient. But it probably isn't the best or even most affordable method for getting the nutrients to your plant long-term. In the instance that you do have a lack of magnesium in the soil, other amendments are preferable.
Is it worth using at all?
Are you wondering why the world is even talking about Epsom salts for plants if they’re not ideal for the home gardener? I suspect tradition has something to do with it. My grandmother has provided me with a variety of gardening tips, things she learned way back when that she swears by. Some of the tips are real nuggets of wisdom, while others I’ve tried have failed miserably.
There are some instances, however, where Epsom salt for plants may be beneficial. In large-scale growth efforts, magnesium deficiency isn’t a small possibility, it’s common. But, Epsom salt is not a practical option for high-volume operations since it happens to be costly in larger quantities.
Other options exist for dealing with magnesium deficiency and include dolomitic lime, sulfate of potash-magnesia, certain types of manure fertilizer, and soybean meal.
If you’re not convinced and want to try using Epsom salts for plants in your garden, you can apply it via foliar spray (mix 1 tablespoon into a gallon of water), or you can apply it directly at the base of a plant (about a tablespoon should do it, as well).
If you really want to test things out, try growing two identical plants: one with Epsom salt fertilizer and one without. Then let us know in the comments if you noticed a difference.
Remember, Epsom salt is not the same as table salt! Table salt, or sodium chloride, in large doses, is better suited for killing pesky weeds. Diluted to a mild solution, you can use it to battle cabbage loopers and other worm-like pests.
The bottom line is this: we're all for a great, affordable option for improving the garden. But it's important to understand the science behind any solution. The science backing Epsom salts for plants in the garden isn't there, yet.