Using Epsom salts in the garden is a popular gardening trend and I wanted to see if they’re good for fruit trees. The only problem is there’s not a lot of good information out there. So, I did more research to be sure. Here’s what I found.
Epsom salts are generally bad for fruit trees as they’re a fast-release fertilizer, dissolving quickly into the soil. As a result, the fruit tree can’t absorb it well, and excess Epsom salts overwhelm the soil with magnesium toxicity. For best results, use a slow-release fertilizer to address magnesium deficiency.
So, while Epsom salts aren’t great for fruit trees, when can they be used, and what’s a better option? Let’s take a closer look.
Why Epsom Salts Are Bad For Fruit Trees
While we all want to use common household products as cheap, simple, and effective fertilizers, the reality is some are actually bad for plants.
The primary issue with using Epsom salts in the garden is that it’s super easy to dissolve in water. This might sound like a good thing, but it causes the nutrients to wash too deep into the soil (leaching), out of reach of the plant’s roots.
The result is much of the magnesium and sulfur found in Epsom salts goes unused.
For example, one study showed 49% of the Epsom salts were immediately leached through the soil, unusable to plants.
The water-soluble quality of Epsom salts is even worse in sandy soils as they have more drainage than clay soils. And even though clay soils are great at holding nutrients (and water), Epsom salts still aren’t the best solution.
“Very heavy applications of Epsom salts might temporarily correct magnesium deficiency, but chemical overdosing is not an environmentally sustainable practice.”Linda Chalker-Scott, Ph.D., Urban Horticulturist and Associate Professor at Washington State University
According to Dr. Linda Chalker-Scott, here are the results of using Epsom salts in the garden:
- Short-Term: Possibility of a temporary magnesium fix
- Long-Term: Contributing to an overload of nutrients and groundwater contamination
Overall, I recommend not applying Epsom salts unless you’re heavily producing crops, and/or you’ve tested the soil and found a magnesium deficiency. Even then, slow-release fertilizers are likely better.
So, if Epsom salts aren’t good to use, what’s the best way to address a magnesium deficiency in fruit trees?
How to Properly Fix Magnesium Deficiency in Fruit Trees
When plants are deficient in magnesium, they’re too stressed to use other nutrients. Excess magnesium won’t fix this issue either.
The main ways of identifying magnesium deficiency in your fruit tree are if its leaves are yellow with green veins, or if you’ve tested the soil and found a magnesium deficiency.
At this point, it’s a good idea to amend the nutrients in the soil.
The best way to do this is with a slow-release fertilizer or compost. For example, use an organic fertilizer 1-2 times per year and/or 2 inches of compost every 1-2 months. Compost also promotes ideal water retention and overall soil health.
Tip: If you’re looking for other homemade ways to fix magnesium, use banana peels, kelp, blackstrap molasses, and/or eggshells. They all contain some magnesium and are good substitutes for Epsom salts.
Plants require three main nutrients: nitrogen, phosphorus, and potassium (abbreviated as NPK). Secondary or trace nutrients such as iron, copper, and magnesium are also important for plants, supporting other functions such as flowering, fruiting, and the immune system.
For example, magnesium contributes to the overall growth of the plant as well as photosynthesis and chlorophyll production.
Fortunately, the majority of fruit tree fertilizers contain sufficient amounts of all of the nutrients required.
However, when dealing with a magnesium deficiency, avoid using high-potassium fertilizers. Excess potassium interferes with magnesium uptake in the soil and roots, even with normal levels of magnesium.
Instead, use a high-nitrogen fertilizer to dilute the potassium levels (increasing the available magnesium).
For example, trees with access to higher levels of nitrogen in the soil were found to be less susceptible to magnesium deficiency than those with less nitrogen.
Tip: While most fruit trees normally prefer a balanced fertilizer, citrus and avocado trees prefer double the nitrogen to phosphorus and potassium. For example, a 6-3-3 NPK fertilizer is ideal for these trees.
I suggest using both fertilizer and compost for your fruit trees. To see the fertilizers I use and recommend, see my recommended fertilizer page.
If you do decide to use Epsom salts for your fruit trees, mix 1/2 tablespoon for every 4 cups of water. For sandy or heavy clay soil, first amend the soil by adding 2 inches of compost every 1-2 months. Once the soil is well-draining, apply the Epsom salt solution every 1-2 months.
Why Some Soils Lack Magnesium
There are two ways fruit trees have poor levels of magnesium. The first is if your soil is naturally lacking magnesium (such as if the nutrient has been used up or exhausted). The second is if your fruit tree has an imbalance of other nutrients.
- Soil is lacking magnesium
- Imbalanced nutrients
For example, a high amount of potassium in the soil or plant interferes with the root’s uptake of magnesium. Because of this, it’s recommended to add nitrogen and/or reduce potassium to treat magnesium deficiency.
Magnesium deficiencies are also more common in soil with higher drainage, such as light, sandy, or acidic soils due to their leaching effect. It’s not as likely for clay soil to have a magnesium deficiency, but it’s still possible.
High levels of irrigation or rainfall also contribute to reduced magnesium (as well as other nutrient deficiencies).
More Myths of Using Epsom Salts in the Garden
In case you’ve heard other potential benefits of Epsom salts in the garden, here are several more common myths I’ve found:
- You Can’t Use Too Much: False. You can use too much Epsom salts and overwhelm the other nutrients in the soil (and contribute to contaminated groundwater)
- It Deters Slugs, Voles, Flies, Rabbits, and Other Pests: False. No science can be found to substantiate claims of Epsom salt control on any pest species.
- It Reduces Some Plant Diseases such as Powdery Mildew and Apple Scab: Unconfirmed. There is some evidence, but it isn’t confirmed via peer-review.
- It Increases Seed Germination: Unconfirmed. Most seeds contain enough nutrients to initiate root and shoot growth on paper toweling moistened only with pure water.
- You Should Spray Leaves With Epsom Salt: False. Epsom salt solutions sprayed on foliage is ineffective and often chemically burn the leaves, resulting in leaf scorch. Roots are much better than leaves at nutrient uptake as they’re designed to “mine” the soil.
Who else read these in Dwight’s voice?
Which Fruit Trees Don’t Like Epsom Salt?
The most salt-sensitive fruit trees are peach, cherry, and especially—avocado. These plants don’t do well with high levels of salt in the soil, which is commonly shown as brown leaves. Pear trees are moderately sensitive, and black currants are tolerant of salty soil.
To help with this, avoid using salt to de-ice your driveways and roads as it ends up in gardens (and groundwater).
“Whenever possible, use coarse sand instead of salt to provide traction and make sidewalks and driveways less slick.”Salt Damage in Landscape Plants, Purdue University
Of course, avoid using Epsom salts for these trees as well.
To learn more about why Epsom Salts are bad for the garden, check out this video by Epic Gardening.
Need More Help?
You can always ask us here at Couch to Homestead, but you should know the other resources available to you! Here are the resources we recommend.
- Local Cooperative Extension Services: While we do our best with these articles, sometimes knowledge from a local expert is needed! The USDA partnered with Universities to create these free agriculture extension services. Check out this list to see your local services.
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