Fertilize with Epsom Salts (cont)
By: Charlie Nardozzi
Is Using Epsom Salts Worth a Try?
In their studies, researchers applied Epsom salts directly to the soil. Foliar applications, such as those our test gardeners used, appear to be a better way to guarantee that the plants get the benefits of the added magnesium.
Before you try Epsom salts, test the soil to determine its magnesium content. Don't rely on Epsom salts to correct large soil magnesium deficiencies, but rather use it as a supplement to soils with adequate or slightly low magnesium levels to boost plant growth, flowering, and fruiting. For severely magnesium-deficient soils, use dolomitic lime or Sul-Po-Mag. Foliar applications of Epsom salts seem work better than adding it, dry or mixed with water, directly to the soil. Plants may not efficiently take up magnesium sulfate in granular form, especially in alkaline soils or soils that already test high in potassium, calcium, or magnesium. If you have tested your soil and know it has those qualities, a foliar application is a faster way to get the nutrients to the plant.
Many rosarians agree that Epsom salts-treated planats produce more new canes at the bottom of the plant (bottom breaks) and darker green foliage. Recommendations on how much to use vary, but generally you can apply 1/2 cup of granules in spring before buds first begin to open and 1/2 cup in fall before leaves drop. Apply a foliar spray (1 tablespoon per gallon of water per foot of shrub height) after the leaves open in spring and again at flowering.
Tomato and Peppers
Magnesium deficiency in the soil may be one reason your tomato leaves yellow between the leaf veins late in the season and fruit production slows down. Test your soil every 3 years or so to check on nutrient levels. Epsom salts can keep plants greener and bushier, enhance production of healthier fruit later in the season, and potentially help reduce blossom-end rot. Apply 1 tablespoon of granules around each transplant, or spray a solution of 1 tablespoon Epsom salts per gallon of water at transplanting, first flowering, and fruit set.
Epsom salts is available in drug and grocery stores.
Epsom salts works best on soils that are...
- Slightly deficient in magnesium
- Alkaline (show high pH) as in western areas
- Old, "weathered," and acidic (with low pH) soils of the Southeast and Pacific Northwest
- High in calcium and potassium (western soils)
Charlie Nardozzi is a senior horticulturist at National Gardening.
Photography by John Goodman