Epsom salt (magnesium sulfate) is a naturally occurring mineral compound used as an inexpensive lawn supplement. It contains magnesium, a central atom in chlorophyll, and sulfur, which is essential for protein and enzyme formation in grass. Applying this compound can help turfgrass achieve a deeper green color and improve its ability to absorb other nutrients like nitrogen and phosphorus. This guide provides steps for determining if your lawn needs this supplement and the methods for safe application.
Assessing Your Lawn’s Requirement for Magnesium
Epsom salt is not a general-purpose fertilizer; unnecessary application can create a nutrient imbalance that harms your turf. Use magnesium sulfate only if a soil deficiency is confirmed. The most definitive method for determining nutrient levels is to send a soil sample to a professional testing laboratory. This test provides a precise analysis of your soil’s magnesium content and pH level, ensuring the application is warranted and correctly dosed.
Visual cues can suggest a magnesium supplement may be needed. A lack of magnesium typically presents as interveinal chlorosis, where the tissue between the leaf veins turns yellow or pale green while the veins themselves remain green. This yellowing is most noticeable on the older, lower leaves of the grass blades, as the plant moves its limited supply of magnesium to support new growth.
Magnesium deficiency is more common in sandy soils prone to leaching, or highly acidic soils with a low pH. It can also occur in soils with naturally high levels of calcium or potassium, as these minerals compete with the grass’s uptake of magnesium. Applying Epsom salt without a soil test risks creating an excessive amount of magnesium, which can inhibit the absorption of other essential nutrients.
Calculating Ratios for Liquid and Dry Preparations
Once a magnesium deficiency is confirmed, prepare the Epsom salt in either a liquid solution for spraying or a dry form for spreading. For a liquid application using a standard garden sprayer, a common ratio is to mix two tablespoons of Epsom salt into every gallon of water. Stir the mixture thoroughly until the crystals are completely dissolved, ensuring the magnesium sulfate is readily available for absorption.
When opting for a dry application, the recommended rate is generally about one-half pound of Epsom salt for every 100 square feet of lawn area. This translates to an application rate of approximately five pounds per 1,000 square feet. This granular form requires the use of a broadcast or drop spreader to guarantee even distribution across the turf. Using a calibrated spreader prevents the concentration of salt in small areas, which could otherwise lead to localized turf burn.
Another guideline for dry application is three pounds of Epsom salt for every 1,250 square feet of lawn. The total amount of magnesium applied annually should not exceed ten pounds per 1,000 square feet, unless a soil test indicates a severe deficiency. Calculating the precise area of your lawn is necessary to avoid over-application, which can upset the balance of soil nutrients.
Techniques and Timing for Effective Application
The physical application technique depends on whether you prepared a liquid or dry solution. For the liquid mixture, use a pump sprayer or a hose-end sprayer, aiming for even coverage across the entire lawn area. The goal is to drench the soil surface, not the grass blades, ensuring the dissolved magnesium sulfate reaches the root zone quickly. Avoiding oversaturation is necessary to prevent the solution from running off the lawn.
If using the dry, granular method, load the calculated amount of Epsom salt into the spreader and set the calibration to a low rate. Apply half of the calculated amount while walking the lawn in one direction, and then apply the remaining half by walking perpendicular to your first pass. This cross-hatch pattern helps ensure uniform distribution and minimizes the risk of streaking or missed spots.
Immediately following a dry application, water the lawn thoroughly with about one inch of water. This irrigation dissolves the salt crystals, moving the magnesium and sulfur into the soil where the grass roots can access them. Failing to water the dry salt in will leave the crystals on the grass blades and soil surface, causing them to draw moisture from the turf and potentially burn the grass.
The optimal timing for application is during the cooler parts of the growing season, typically in early spring or early fall. Applying Epsom salt during these periods supports the grass’s active growth phase. Apply the product in the late afternoon or early evening, allowing the solution to absorb into the soil before the heat of the day. Avoid applying Epsom salt during periods of extreme heat or drought stress, as this can exacerbate damage to the lawn.