While Epsom salt has a reputation as a good fertilizer, most soils in Kansas already contain the essential magnesium and sulfur that Epsom salt provides.

As you gear up for gardening season, the idea of using common household products to save money, reduce the use of synthetic products or return to an old way of doing things in the garden might seem attractive.

There are a lot of suggestions along these lines floating around out there, and one of the most common is using Epsom salt as a fertilizer and a pest control agent. Epsom salt has a history of use in agriculture, but before you stock up on the mineral compound, consider whether use is really warranted in your garden or on your plants.

Epsom salt is magnesium sulfate. Its key components, magnesium and sulfur, are essential to plant growth, so the idea of Epsom salt as a fertilizer is sensible.

However, like any other fertilizer, too much of a good thing may be just a waste of time and money. In worse examples, too much fertilizer is also an environmental issue.

What complicates the issue of Epsom salt’s effectiveness is that Epsom salt might be beneficial in some soil types, while being a complete waste in others.

How do you know the difference? A soil test can help, but it only provides part of the picture. Soil pH and texture affect a soil’s ability to retain nutrients like magnesium and sulfur, but they also affect a plant’s ability to absorb certain nutrients. That means magnesium and sulfur deficiencies can occur in plants even when adequate amounts of magnesium and sulfur are found in the soil in which the plant is growing.

In Kansas, true magnesium and sulfur deficiencies are rare. These deficiencies are most common in acidic soils and in the types of soils typically found in the Southeast and Pacific Northwest. Kansas soils are typically alkaline, although they may be high in calcium or potassium, which can also affect magnesium uptake.

The belief in Epsom salt’s benefits to the garden probably comes from its use as a fertilizer in intensive cropping systems with known magnesium deficiencies. In research done in home garden settings, Epsom salt has been applied to the soil and directly to plants as a foliar solution, with few observations of any difference in plant growth.

Epsom salt is also unproven in the arena of pest control. If it worked as a fertilizer, a plant might be less susceptible to insects and disease or better able to withstand attacks. Unfortunately simply sprinkling it around your plants is unlikely to ward off any pests.

Epsom salt gets its name from the town of Epsom in England, where it was originally extracted from springwater. In addition to its purported benefits in the garden, it is said to have a number of uses in health and personal care.

— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation. She is the host of “The Garden Show.” Send your gardening questions and feedback to features@ljworld.com.