Fertilizing Citrus Trees With Epsom Salt: A Budget-Friendly Hack Or Garden Nightmare

Epsom salt has so many smart uses around the house that you may find yourself wondering if there's anything it can't do. Well, it's not just handy inside the house — many gardeners swear by it, too. At less than $25 for 19 pounds of Dr Teal's Multipurpose Unscented Epsom Salt, it's easy to understand why citrus tree growers might think that fertilizing with Epsom salt is the best budget-friendly hack. For contrast, a quart of Botanicare Cal-Mag Plus will run you almost $20 and provides other micronutrients like iron and calcium. Just four pounds of Espoma Organic Citrus-Tone 5-2-6 Natural & Organic Fertilizer and Plant Food costs over $15, so relying on the bag of Epsom salt you already have in the medicine cabinet may be the most affordable way to occasionally add magnesium into the soil. 

The key to making sure this doesn't take a turn from a budget-friendly hack to a garden nightmare is getting your timing right — and, perhaps, testing your soil first. Epsom salt is a handy fertilizer for plants that are magnesium-deficient. However, it won't address all of your citrus plant's needs, and could cause other issues if used improperly. Citrus trees require potassium, and magnesium can compete with this essential nutrient for absorption, so timing is crucial. Both magnesium and potassium deficiencies can cause changes in the leaves of citrus trees, so testing your soil is key to correctly identifying the problem. 

At the chemical level, Epsom salt is a combination of magnesium and sulfur. Importantly for citrus gardeners, these nutrients play a vital role in producing fruit and chlorophyll. When it comes to Epsom salt and what it does in your garden, adding it to the mix can help produce more fruit. However, misusing it can cause serious problems.

Plants experiencing a magnesium deficiency will often have yellow leaves that drop prematurely. Still, there could be other culprits for similar symptoms, so don't rush to assume you have a magnesium problem. For instance, otherwise evergreen citrus trees may yellow, or even drop their leaves, in cooler climates. A potassium deficiency also causes leaves to change color and drop, and can result in fruit with thinner skins. This can lead to your fruit splitting. If you suspect a magnesium deficiency, test your soil before jumping to conclusions.

If your trees are showing signs of potassium deficiency, you may want to steer clear of Epsom salt, as it can make the problem worse by interfering with potassium absorption. While citrus trees generally prefer a balanced fertilizer with high levels of nitrogen and medium levels of potassium, feeding mature trees with Epsom salts about three times a year can keep them looking their best and producing more fruit. The key is to stagger the feedings, as too much magnesium from Epsom salts can seriously affect oxygen levels in soil. Sometimes, Epsom salt is even used as a spray for foliage rather than the roots. However, this can damage your plant's leaves. To prevent a garden nightmare, it's important not to overuse Epsom salt.

For citrus trees planted in the ground, you will find a wide variety of advice for how best to apply Epsom salts. For instance, you can try working two tablespoons into the soil around the root zone of mature trees. If it's easier to water your trees, add one teaspoon of Epsom salt for every liter of water you use. We highly recommend looking up the best practices for your specific tree and growing conditions before using this hack. If you're growing a Meyer lemon in a pot, how you use Epsom salt will be very different from how you use it on your outdoor orange tree.

Keep in mind that citrus trees aren't the only garden plants that can benefit from Epsom salts. You can also fertilize your avocado tree with this common household ingredient, and it is often used with tomatoes and even roses, which require magnesium to grow. Just be careful not to overuse Epsom salt, and inadvertently cause other problems such as nutrient imbalances and damage to the leaves.