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How to Use Epsom Salt in Your GardenMartina Unbehauen - Getty Images

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Epsom salt for plants can be a great addition to a healthy garden and help many plants to grow and flower. The mineral salt can help seeds germinate, encourage more flowers, promote denser growth, increase chlorophyll production, and even deter pests like slugs and voles. However, it’s not always needed (or helpful). Keep reading to learn when it’s a good idea to use Epsom salt on plants and when to hold off.

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What Is Epsom Salt?

Epsom salt, or magnesium sulfate, is a combination of magnesium, oxygen, and sulfur. It’s most definitely not the same thing as the white stuff you sprinkle on French fries, and if you were to use regular iodized or kosher salt on your garden, it would kill your plants—the kind of salt matters!

Epsom salt for plants in the garden is the same salt, however, that some people buy by the pound to add to warm baths. Many believe it can have a relaxing and pain-relieving effect on sore muscles. Just use a non-scented type for your garden.

Epsom Salt for Plants

Epsom salt can deliver great results in gardens that have a magnesium deficiency when used correctly. Roses, tomatoes, peppers, pansies, petunias, and impatiens particularly love Epsom salt, and all need high levels of magnesium for optimal growth. Tests by the National Gardening Association confirm that “roses fertilized with epsom salt grow bushier and produce more flowers, and it also makes pepper plants grow larger than those treated only with commercial fertilizer.”

When to Use Epsom Salt for Plants

If your soil has a magnesium deficiency, Epsom salt can help. A soil test is the best way to determine that (here’s how to find a county extension near you to test your soil), but there are visual clues too. “Some common deficiency symptoms are yellowing of the leaves between the veins, leaf curling, stunted growth, and lack of sweetness in the fruit,” according to The National Gardening Association.

Which Plants Don’t Like Epsom Salt

If your garden doesn’t have a magnesium deficiency (as determined by a soil test or visual clues), you can worsen existing garden conditions by adding Epsom salt since too much magnesium can prevent much needed calcium from getting to your plants.

Vegetables such as beans, peas, lettuce, and spinach can grow and produce good yields in soil with low magnesium levels and therefore don’t like Epsom salt.

How to Use Epsom Salt for Plants

According to the Epsom Salt Council, here’s how much to use and when to apply it:

  • Houseplants: 2 tablespoons per gallon of water, monthly

  • Roses: 1 tablespoon per foot of plant height per plant, every two weeks; add a tablespoon of Epsom salt to each hole at planting time

  • Tomatoes, peppers, pansies, and petunias: 1 tablespoon/gallon of water per plant every two to four weeks during the growing season

  • Evergreens, azaleas, and rhododendrons: 1 tablespoon per 9 square feet; apply over root zone every two to four weeks

  • Trees: 2 tablespoons per 9 square feet; apply over the root zone three times annually


Which Plants Like Epsom Salt?

Plants that thrive in magnesium-rich soil like Epsom salt. Examples include many houseplants, roses, common garden crops like tomatoes and peppers, evergreens, and many trees. You can use to fortify your lawn if your soil is low in magnesium too.

Can I Just Sprinkle Epsom Salt on Plants?

If you’re applying Epsom salt before planting, you can sprinkle it on the soil and mix it in, according to the Epsom Salt Council. Otherwise, it needs to be diluted with water. For individual plants, mix it with water and then spray it on; you can find the exact amounts to use above or on the Epsom Salt Council website. For your lawn, apply it with a spreader and then use a garden hose or sprinklers to water it into the grass.

Does Epsom Salt Kill Weeds?

Epsom salt is a fertilizer—not a pesticide. It can help plants, including weeds, grow, according to the University of Florida Agricultural Extension. Like vinegar weed killer, DIY Epsom salt recipes you see online won’t kill weeds.

How Much Epsom Salt Do I Use Per Gallon of Water?

It depends on which plants you want to use the Epsom salt on. One to two tablespoons per gallon is typically the amount used for houseplants and individual garden plants like tomatoes and peppers.

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