Epsom salt and saltpeter are composed of essential macronutrients plants needs for optimal health.

Epsom Salts & Saltpeter for Yards

by Casandra Maier

As a mom, it is important to be aware of the ingredients in your lawn and garden fertilizers and amendments. This lets you know what products are safe to use around your children and pets, and which ones you need to use with caution. Simple organic compounds are generally the safest with the added benefit of being healthier for the environment. Epsom salts and saltpeter are two simple mineral compounds that are used to supply nutrients and improve the health of your garden landscape. With proper use and application, these compounds add vibrancy and aesthetic beauty to your lawn and plants.


Epsom salts, also known as magnesium sulfate, are composed of 9.8 percent magnesium and 12 percent sulfate, another name for sulfur, states the University of Hawaii. On the other hand, saltpeter is another word for potassium nitrate, a combination of 44 percent potassium and 13 percent nitrate. Nitrate is one of the most readily available forms of nitrogen, making it easy for uptake by plants. All four of these nutrients are essential for plants of all kinds, from your lawn grasses to herbaceous plants, trees and shrubs. They assist in healthy growth and development of plant tissues, increase longevity, improve the yields of flowers and fruits and free up other nutrients in the soil so plants growing in your yard have balanced nutrition.

Epsom Salt Uses and Benefits

Epsom salts are useful as an amendment in your yard for everything from flowering shrubs, to your garden, to your lawn. In healthy amounts, Epsom salts provide a boost of magnesium and sulfur in your yard, giving you noticeably softer, greener grass, luscious plants, increased flowering and larger fruit and vegetable crops. Furthermore, Epsom salts are gentle and safe to use around your children and pets.

Saltpeter Uses and Benefits

Saltpeter is useful as a side or top dressing in plants when you notice problems due to a lack of nutrition. In the proper amounts, saltpeter improves the quality of your plants, increasing their health and vigor. Increased vigor means plants are better able to withstand the elements, such as drought, frost and temperature fluctuations. Increased disease resistance is also a benefit of using saltpeter, according to the Potassium Nitrate Association. In high doses, the salinity of saltpeter allows you to remove unwanted woody plants or tree stumps with greater ease. While saltpeter is less toxic than chemical-grade fertilizers, it is still toxic in nature, and pets and children should stay away from areas where saltpeter is used following application.

Properties and Considerations

Both Epsom salt and saltpeter have the potential to cause burning and scorching in your grass and plant leaves if used incorrectly in large amounts. Therefore, follow the ratios for appropriate application. Both compounds easily dissolve in water. Epsom salt does not change the pH of your soil and does not build up in the like other chemical fertilizers. Saltpeter does raise the soil pH, which may be undesirable depending on your soil’s pH level and the plants you are growing in your yard. Saltpeter is also chloride-free.


For use as a foliar spray, mix 1 tablespoon of Epsom salt with a gallon of water and apply after planting, in another month or so as plants begin to grow, and once again when the plants mature. Add 1 cup of the material to the soil per each 100 square feet of garden space before planting. For houseplants, dissolve 2 tablespoons of Epsom salt in a gallon of water and use the solution for your regular watering routine.

Photo Credits

  • Chris Clinton/Digital Vision/Getty Images