Last Updated: April 7, 2023
Epsom salt has long been touted as a quick fix for basically anything in the garden. I’ve seen it said that it can fix blossom end rot, stunted plant growth, yellowing leaves, and more in tomato plants.
Well, not to ruin your day, but epsom salt is more likely to harm your tomatoes than help them. In this article, I’ll share the reality of what epsom salt does for tomatoes and other veggies.
This isn’t the only misleading garden “hack” you’ll hear about! From using eggshells to feeding your plants aspirin, you’ll have to do your own research to learn the facts.
What Is Epsom Salt?
Pure epsom salt is made up of magnesium sulfate. Essentially, it is a water-soluble crystallized salt that contains magnesium and sulfur.
The word Epsom comes from the English town where the compound was first discovered. Since then, it has been widely used as a bath soak to help many ailments.
It is still used today as a primary ingredient in bath soak products and is considered beneficial. Many claim that epsom salt helps reduce inflammation, soreness, and muscle aches. However, there is little scientific research backing up the claims.
What Does Epsom Salt Do For Tomatoes?
When you dissolve epsom salt in water, then water your plants, you’ll be adding magnesium and sulfur to the soil. Both of these compounds are in fact necessary for growing tomatoes.
However, many soils already have plenty of magnesium and sulfur to begin with. In this case, adding more may have negative consequences on your tomatoes.
But Tomatoes Need Magnesium, Right?
Yes, tomatoes require magnesium for proper plant development. A magnesium deficiency in the plants will cause chlorosis (yellowing leaves) between the veins of tomato leaves. This will begin at the lowest leaves of the plant and work its way up over time.
So why not add epsom salt to your soil? Well, if the soil already has enough magnesium, it is a bad idea to overload it with excess. Too much magnesium in the soil can actually lock out availability of calcium, another vital nutrient.
This imbalance between magnesium and calcium can lead to blossom end rot and other calcium deficiency symptoms. It is critical to know your soil’s nutrient content, first.
When Should I Add Epsom Salts?
If you’ve already got yourself a bag of epsom salts, don’t feel the need to throw it away. It may still be handy in the garden in select circumstances.
- Magnesium deficiency. The only way to know for sure that you have a magnesium deficiency is to get a soil test. This will indicate the level of nutrients in your ground soil and make specific recommendations to improve it. Epsom salt may come in handy in this case.
A soil test is a great idea, especially in a new garden, or one that has seen failures. If you have especially sandy soil, it is possible that magnesium is deficient, but not guaranteed. Send away some of your soil to know for sure.
Always be careful with the amount of epsom salt you are adding to your soil, as magnesium is a secondary nutrient. This means that it is required for plant growth, but in small quantities. Ultimately, it is best to leave this to the professionals who manufacture fertilizers.
What Should I Use Instead?
It is much safer to use an all-purpose fertilizer that contains magnesium and calcium, such as Espoma Garden or Tomato Tone, or similar. Too much of one can lock out the other nutrient from your plants, leading to growth issues.
Many gardeners recommend putting a tablespoon or so of epsom salt into the hole when you transplant your tomatoes. This is very unscientific, and I just wouldn’t recommend it.
Instead, simply use a nutrient-rich potting soil for container plants (this soil has worked amazingly well for me).
If you’re growing in the ground, amend your garden soil with compost or all-purpose fertilizer. These balanced additions will add all the required nutrients on a slow-release schedule that is unlikely to cause problems.
Remember, epsom salt is not a fix-it-all amendment and should not just be tossed in for the heck of it! You may just end up doing your tomato plants a disservice.
Can I Spray Epsom Salt On Tomato Leaves?
Okay, so epsom salt may not be the best idea to add to your soil, but what about as a foliar spray? Many claim that dissolving some in water and spritzing tomato leaves can alleviate a deficiency, improve yellowing leaves, and even stop blossom end rot.
However, the only thing you should expect after spraying your tomatoes with an epsom salt solution is a sunburn. Spraying tomato leaves with epsom salt can easily cause sun scald, or white burn marks on the leaves.
Many gardeners are set in their ways and may dismiss this article, continuing to add magnesium sulfate to their soil. However, I recommend only adding what you know your tomatoes need to thrive. Happy growing!