Keep Your Orchids Happy And Healthy With A Simple Epsom Salt Hack

Should you use Epsom salt to improve the health of your orchids? Many gardeners swear by this hack, YouTube videos tout its benefits, the American Orchid Society recommends it, and – surprise, surprise – so, too, does the Epsom Salt Council.  But other websites, gardening associations, and videos warn you against it. What does the science say? The answer is a definite – maybe.

Horticulturalists from Michigan State University claim "there is no scientific evidence" that Epsom salt will induce orchids to flower. Yet a 2023 study presented in Global Ecology and Conservation found that orchids stay in flower longer when treated with four key nutrients, including magnesium and sulfur found in Epsom salt. Both magnesium and sulfur are essential plant nutrients, and a deficiency in them often appears as yellow leaves. Magnesium is also important for photosynthesis and the strengthening of cell walls, and, along with calcium and silicon, promotes pollen and seed development. 

If you want to try this hack, you'll want to know how much Epsom salt to use. Overuse can lead to negative consequences with orchids, potentially including leaf scorch, root disease, and the obstruction of other key nutrients like calcium. But the correct use may lead to the beautiful, healthy orchids you were hoping for. A lot of anecdotal evidence points to the benefits of Epsom salt, but it may be that your plants need more than one simple hack. The key is to figure out what your orchids need and what your soil is missing.

Before applying Epsom salt to your orchids, get a free soil test from your state's cooperative extension service in order to figure out what key components of soil are missing. You can also find test kits on Amazon and in garden centers, but we've yet to find one that tests more than the major nutrients nitrogen, phosphorus, and potassium. 

If your soil test comes back and identifies a lack of magnesium and sulfur as the main deficiencies in your soil, then try spraying 1 tablespoon of Epsom salt per each gallon of water directly on the foliage, rather than adding it to the soil. Apply after transplanting, at first flowering, and again at fruit set. The results may be stronger stems, lusher foliage, and longer-lasting flowers – well worth the effort.

If your soil test reveals a more general lack of nutrients, apply a commercial or homemade orchid fertilizer, one that contains key minor nutrients (including sulfur, calcium, and magnesium) as well as the major ones. And water no more than directed: over-watering washes nutrients out of the soil. 

Your best bet may be to top-dress your soil with organic compost, which gives your plants a long-lasting, balanced diet. Just listen to your soil: it will tell you what it needs. Take all the testimonials, positive or negative, about the benefits of this or that simple hack with, well, a grain of salt.