How Often Should You Put Epsom Salt on Tomatoes?

You can use Epsom salt for many things in life, and it has more than a few uses in the garden. Since it contains magnesium, it works as an excellent food source for tomato plants. But how often should you put Epsom salt on tomatoes?

You should put Epsom salt on tomatoes once a month by mixing 1-2 tablespoons (15-30 ml) of the product with one gallon (3.8 liters) of water. Continue to water your tomato plants regularly throughout the month. You can also add some Epsom salt to your fertilizer mix.

The rest of this article will discuss why you should use Epsom salt once a month on tomatoes. It will also discuss if you can use it more frequently than this, how to put it on tomatoes, and signs your tomatoes need Epsom salt.

Why Should You Use Epsom Salt Once a Month on Tomatoes?

You should use Epsom salt once a month on tomatoes because that is generally how long it will take for your plants to consume all the nutrients. Once a month has passed, you can assume your plants want more magnesium and give them more Epsom salt.

Magnesium is the main ingredient in Epsom salt, and tomatoes need this mineral to thrive. When tomatoes have adequate magnesium, they can be:

  • Tastier
  • Juicier
  • More vibrant in color
  • Healthier

So, giving tomatoes Epsom salt once a month will ensure they have a consistent supply of magnesium. In turn, this will ensure that they can thrive throughout the fruiting season.

Should You Put Epsom Salt On Tomatoes Weekly?

You shouldn’t put Epsom salt on tomatoes weekly because you’ll likely overfeed them, which is damaging. Giving your tomatoes large amounts of Epsom salt weekly can result in magnesium toxicity, which can eventually lead to death.

By feeding your tomatoes Epsom salt weekly, they could experience symptoms of magnesium toxicity. These symptoms include the following:

  • Slowed growth
  • Dull, dark-colored fruits
  • Fewer fruits
  • Tomatoes that don’t taste good

Plus, magnesium toxicity can cause the tomatoes to be unable to take in some other essential nutrients, like calcium. 

Can You Put Epsom Salt On Tomatoes Every Second Week?

You can put Epsom salt on tomatoes every second week if you use small amounts and water the plants regularly. However, it’s best to apply the salt monthly using 1-2 tablespoons (15-30 ml) per gallon (3.8 liters) of water.

As you know from the last sections, giving Epsom salt to tomatoes too frequently can cause magnesium toxicity. So, it’s best to avoid using it biweekly. 

However, if you use less product, there shouldn’t be any issues with applying it this frequently. Some people might prefer doing it this way because it feeds the tomatoes in a slightly more controlled manner (using less Epsom salt more frequently).

Can You Put Epsom Salt On Tomatoes Once Every Three Months?

You can put Epsom salt on tomatoes once every three months, but it’s better to do it more frequently. Within a month, most of the Epsom salt in the soil will already be gone, so your plant won’t receive many additional nutrients if you wait three months between feedings.

Of course, this is only necessary if your soil lacks magnesium. If there’s plenty of magnesium in the soil, it won’t be necessary to apply the Epsom salt once a month. In that case, applying it once every three months is perfectly fine (you could even avoid using it altogether in this case).

How to Put Epsom Salt on Tomatoes

Now that you know how often you should put Epsom salt on tomatoes, it’s good to know exactly how to do it. Applying it to the plants and soil incorrectly could cause magnesium toxicity or other issues, and you certainly want to avoid that! 

Below, let’s look at the two main ways you can put Epsom salt on tomatoes:

Mix With Fertilizer

If you want to give your tomatoes an added boost, you can mix a teaspoon or two of Epsom salt with your regular fertilizer mixture. Most fertilizers already contain magnesium, but adding some extra shouldn’t cause any harm. 

It’s important to remember that you shouldn’t use 1-2 tablespoons (15-30 ml) if you’re using this method. Instead, you’ll be using 1-2 teaspoons (5-10 ml). If you use tablespoons, you’ll likely add too much Epsom salt into the fertilizer mixture because fertilizer already has specific amounts of the magnesium micronutrient. Adding more will increase the risk of plant damage.

Once you’ve mixed the Epsom salt with the rest of your fertilizer, you can apply it to the tomatoes as you normally would. You can repeat this anytime you fertilize your tomatoes, which is likely every two weeks.

Mix With Water

This method is more common and doesn’t require mixing anything with fertilizer. If you choose to do it this way, you’ll need to mix 1-2 tablespoons (15-30 ml) of Epsom salt with a gallon (3.8 liters) of water. Then, you can add it to the plants as if you’re watering them regularly. Make sure to distribute the mixture evenly.

When using this method, it’s best to repeat it monthly for the best results. Between Epsom salt feedings, you should water your tomato plants as you normally would. You can use a watering can for this method, as it’s the easiest way to distribute the Epsom salt and water mixture.

Can Epsom Salt Damage Tomatoes?

Epsom salt can damage tomatoes if you use too much of it or apply it too frequently. All Epsom salt contains magnesium, and tomatoes need small amounts of magnesium to thrive. If you feed them too much magnesium, they can experience problems that may eventually result in plant death.

While not enough magnesium results in yellowing leaves, too much of it causes the leaves to turn a brownish color. To avoid this, make sure you use the recommended amount of Epsom salt at the recommended times.

Excess Magnesium May Contribute To Blossom End Rot

Blossom end rot is another common issue that can occur due to tomatoes receiving too much Epsom salt. This happens when the tomatoes don’t receive enough calcium, which is usually caused by too much moisture. 

However, too much magnesium can make tomatoes unable to take in adequate calcium levels, eventually leading to blossom end rot. And as you know, Epsom salt’s primary ingredient is magnesium.

Blossom end rot turns the tomatoes to rot, starting from the bottom. To avoid this disease, you should pay close attention to the amount of magnesium you’re feeding your tomatoes (and the soil’s moisture levels).

Signs Your Tomatoes Need Epsom Salt

If you’re deciding whether or not to use Epsom salt on your tomatoes, you might be wondering what the signs of magnesium deficiency are. If your plants show signs of magnesium deficiency, feeding them Epsom salts is an excellent way to fix the problem or prevent it from worsening.

The main signs your tomatoes need Epsom salt are:

  • Yellow leaves. When leaves turn yellow, it’s a sign that the plants aren’t receiving enough magnesium. Therefore, using Epsom salt could fix the issue. However, it’s essential to realize that yellow leaves can indicate other problems that you should consider.
  • Brown splotches. Another sign of magnesium deficiency is brown splotches around the leaves. This can occur along with yellowing leaves. Still, brown splotches may indicate another issue, such as under or overwatering.
  • Leaves falling early. If you notice leaves falling off your tomato plants earlier than usual, there may be a lack of magnesium.

Every time you notice these symptoms, feeding your plants some Epsom salt may be a good idea—that is, of course, if you’ve ruled out other issues like overwatering or sunburn.

What To Use on Tomatoes Instead of Epsom Salt

If you don’t have any Epsom salt in your home or want to try different products, there are a few options to consider. The most common alternative to Epsom salt is lime because it is also high in magnesium. 

Now, let’s look at the two main alternatives to Epsom salt for tomatoes in greater detail:


Lime is good for magnesium-deficient tomatoes and can be used in place of Epsom salt. It also makes the soil less acidic, so if acidity is an issue, this could help. To apply lime to the soil, you can spread it around using a shovel or spreader. 

You generally only need to apply it once or twice a year, so it’s a low-maintenance method compared to Epsom salt.


Standard compost is another soil amendment and fertilizer high in magnesium. For that reason, you can use it as a replacement for Epsom salt if you wish. Like with lime, it’s generally only necessary to add compost to the soil once or twice a year. So, you won’t have to apply it once a month like you would with Epsom salt.

Of course, composting is high-effort because you need to make it yourself. Plus, it takes a long time to prepare and decompose. If you’re okay with this, compost is an excellent alternative to Epsom salt for your tomatoes.


You should put Epsom salt on tomatoes once a month by using 1-2 tablespoons (15-30 ml) of the product with a gallon (3.8 liters) of water. Using too much Epsom salt or using it too frequently could result in magnesium toxicity.

You can add it to your regular fertilizer mix by adding less Epsom salt. All you need to do is add it to the mixture and fertilize it as you usually would.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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