Epsom Salt for Plants: What Likes It and What Doesn't
Plants that don’t like Epsom salt include carnivorous plants such as Venus flytraps and pitcher plants, succulents and cacti, and any plant growing in soil that already has enough magnesium. Epsom salt is magnesium sulfate, and extra magnesium can block calcium uptake and burn leaves. University of Minnesota Extension advises using it only when a soil test shows a magnesium deficiency.
Below, you’ll learn what Epsom salt does for plants, which plants may benefit, how much to use, and the myths to skip. If yellow leaves made you reach for Epsom salt, find the real cause first, since magnesium is only one of many reasons leaves turn yellow.
What is Epsom Salt?
Named after a humble town in England where it was first found, Epsom salt is a white crystalline substance similar to table salt's physical properties but is composed of a different chemical compound–magnesium sulfate. Its accidental discovery became a pivotal point in the earlier field of chemistry and medicine for its laxative effects. In the modern-day era, it is still used as a raw or primary material in top industries, including beauty and health care products. In plants, it is widely used to correct soil deficiencies, primarily linked to low chemical element levels.
Can Epsom Salt be Used on All Plants?
Is Epsom salt good for plants? The grainy product, per se, is suitable for all plants but with some reservations. Being one of the "primary" secondary nutrients (next to the big three: nitrogen, phosphorus, and potassium), Epsom salts should only be used on plants that suffer from magnesium deficiency symptoms. Some green fellas are tolerant to elevated levels of the element in the soil, mainly vegetable and fruit crops, but some are sensitive and could die a few days after application. Generally, ornamental plants, although unproven, tend to have a low resistance range with concentrated Epsom salt. Therefore, a great precaution should be observed when using Epsom salt in the garden.
What Does Epsom Salt Do for Plants? Is It Good?
There is a scientific explanation to answer the question of what does Epsom salt do for plants. As mentioned earlier, Epsom salts do contain magnesium and sulfur, two of the 16 essential elements plants need to complete their life cycle. Magnesium has an irreplaceable role in crops and ornamental plants, crowning the central core of the chlorophyll molecule that gives the leaves a green pigment. Additionally, it is a critical catalyst or activator of specific plant enzymes needed for the plants' everyday functioning and metabolism. Likewise, sulfur is also a macroelement, absorbed in larger quantities than magnesium, needed for crop growth. Like magnesium, the element is also required to synthesize crucial amino acids and specific glycosides in a few plant families (mustard and the onion family). To sum up, the chemical elements found in the granulated product are essential in aiding crop growth if appropriately applied, bridging the usefulness link between Epsom salts and plants.
What Plants Don't Like Epsom Salt?
Most plants are not adapted to handle concentrated magnesium amounts from Epsom salts. In the following, we listed some fragile plants that should not be fed with the product:
- Carnivorous plants — Pitcher plants, venus flytraps, and sundews are some insect-eating plants that should not be applied with Epsom salts. Because they are adapted to grow in mineral-poor and depleted soil, supplementing fertilizers with even a tiny dosage could mean death to the bug-trapping ornamentals.
- Woody plants — Pine trees and coniferous trees grown along roadsides were reported to be sensitive to magnesium chloride, a chemical compound similar to Epsom salts. Therefore, it would be safe to assume that small trees at home could suffer the same toxicity, primarily for shorter and smaller plants.
- Other indoor tropical plants — If you have small indoor plants that are tropical found, including fiddle leaf fig, tropical palms, aroids like monstera, alocasia, and philodendron; we suggest applying Epsom salt with precaution and in a very diluted solution to prevent toxicity-related leaf yellowing.
Limited studies have only been conducted on houseplants. Therefore, there is no sufficient data to show which plants are sensitive to and up to what threshold Epsom salts can cause toxicity reactions.
What Plants Like Epsom Salts?
Because most plants require the nutrients present in the crystalline substance, the question as to "what plants like Epsom salts" remains open. However, many food crops in the garden, which we listed below, can respond positively to the product:
- Corn — Corn is a domesticated plant that can tolerate relatively concentrated magnesium from Epsom salts within its plant tissue. The element is needed for their growth and production of cobs.
- Tomato — Apply Epsom salts just before tomatoes start to bloom when they need the most critical magnesium concentration. However, apply it with precaution to not cause adverse effects on the plant.
- Pepper — Pepper is a close relative of tomatoes and, therefore, could take Epsom salts with similar levels. Like tomatoes, use the product before the reproductive stage or blooming to take advantage of the maximum nutrient absorption.
- Cabbage — This crop, along with other brassicas (mustard, cauliflower, broccoli), needs a considerable quantity of magnesium.
- Beans — Ever wonder why beans are a rich source of magnesium? That is because it requires magnesium supplements like Epsom salt in heavily depleted soil.
As demonstrated by previous scientific studies, vegetable and fruit crops have acceptable tolerance to magnesium content in Epsom salts. However, the concentration difference between plants that "don't like" and those that "like" remains unclear and will vary depending on the nutrient's presence in the soil.
How to Use Epsom Salts on Plants Indoors?
Applying Epsom salts for plants is easy to prevent magnesium-related nutrient deficiency. The following are some points on how to use Epsom salts on plants indoors:
- Soil incorporation — This method only works before planting or reporting new plants. Sprinkle a few granules of Epsom salts when preparing the potting medium.
- Top dress — The top dress technique is suitable for already standing plants. Epsom salts are spread over the soil and may be covered lightly with dirt. Irrigation water will dissolve through time.
- Pot soaking — This approach of applying Epsom salts will need a container bigger than your plant pot. Dilute the crystalline substance in an appropriate water ratio and soak the pot for a few minutes to seep the nutrients through the potting medium.
- Drenching — In contrast to pot soaking, dissolved Epsom salts in water are drenched or poured at the top rather than allowed to absorb from the bottom.
The top dress is the most convenient application among the four methods, as it only needs to be sprinkled over the topsoil.
How to Use Epsom Salts in the Garden?
After doing a soil test, you are all set to apply Epsom salt to your magnesium-deficient parcel. Follow one of these methods below on how to use Epsom salts in the garden:
- Side dress — This application of Epsom salt is made by digging 1-2 holes next to the plant and covering it with soil. Daily watering and natural rain will dissolve the substance that should be available to the plant roots.
- Foliar — Application through leaf spray is typically made to correct nutrient-related chlorosis or yellowing. Dilute the product in water and apply it to the foliage, where it gets absorbed through the natural plant openings called stomata.
- Soil drench — Rather than applying as pure granules, Epsom salts can be dissolved in water and directly drenched to the root zone. In this manner, the dissolved nutrients will be mass-flowed to the roots rather than staying longer in the soil.
Any of the above techniques will work fine as long as the concentration is correctly applied.
Will Epsom Salt Kill Plants?
Epsom salt cannot kill plants if applied in the appropriate dosage. Magnesium, a chemical element found in the product, can accumulate in the soil and hinder other nutrients from being absorbed. Plants may get killed with concentrated applications.
How Much Epsom Salt Do I Add to My Soil for Plants?
How much Epsom salt for plants should be used? The amount of Epsom salt varies depending on the crop species and the soil's dissolved magnesium content. However, as a rule of thumb, crops grown for food tend to have higher requirements of magnesium, an element present in Epsom salt. On the other hand, ornamental plants have a lower tolerance to nutrients. A soil test is necessary to determine the exact Epsom salt for plants or magnesium supplements. For example, soil with a relatively low magnesium level of 0-50 ppm (0.001g per liter of soil) will need approximately 5g per square meter of soil. If you could imagine, the amount is almost like a pinch of salt in each plant.
Myth and Truth About Epsom Salt and Plants
You have probably heard or read misleading rhetoric about garden salt. In the following, we tried to dissect Epsom salt's benefits for plants which are either partly true or entirely a myth:
- Myth #1 — Epsom Salt is the best organic fertilizer
Epsom salt is neither the best nor an organic fertilizer. Organic fertilizers contain more nutrients and are better than Epsom salt for fertilization purposes. To add, it would not fall as per definition: plant supplements that contain elemental carbon or are derived from natural sources, although this is quite debatable in the field of soil science. However, it would be a great magnesium source for soils lacking this nutrient.
- Myth #2 — Epsom Salt boosts plant growth
The myth may have originated from several cherry-picked data of agricultural crops that were studied to see if Epsom salts for plants dosage is safe and could increase their growth. It indeed resulted in larger-sized crops because the soil, in the first place, was poor in magnesium. Therefore, in lawns and gardens with sufficient levels of the element, it would work like an ashtray on a motorcycle.
- Myth #3 — Epsom salt cures blossom-end rot in tomatoes
Blossom-end rot in tomatoes is primarily caused by the lack of available calcium in the ground. Adding Epsom salts containing magnesium and sulfur will not cure the nutrient-related decay. In fact, too much product concentration could throw off the nutrient balance in the soil and prevent absorption of major minerals like phosphorus and potassium, leading to additional deficiency symptoms.
- Myth #4 — Epsom salt fixes yellowing in leaves
Various causes are related to chlorosis or yellowing of the leaves. This myth is partly correct and will make the leaves green if the reason is related to magnesium. Otherwise, identifying the main root of the problem is crucial to solving the mysterious yellowing of the leaves.
- Myth #5 — Epsom salt prevents pests
Several claims of the pesticidal property of Epsom salts were rampant, but these were not scientifically proven. Plants treated with magnesium salts are still as susceptible as the ones without. While the sulfates in the crystalline chemical have fungicidal activity, the presence of magnesium won't give a significant advantage compared with the standard fungicides. It could even lead to a leaf burn if misapplied.
- Myth #6 — Epsom salt is an excellent weed killer
Because Epsom salt can be lethal to plants in large doses, the myth must have originated from this fact. Like ornamentals, weeds are also plants that get killed with concentrated amounts of Epsom salts. However, its weed-killing nature is impractical in comparison with standard herbicides. The application could branch out to another soil problem, which is detrimental to the plant and the environment.
FAQ
Is Epsom salt good for plants?
Epsom salt is good for plants only when the soil lacks magnesium. Most garden and potting soils already have enough, so extra Epsom salt usually does nothing, or causes harm by blocking calcium uptake. Test your soil before using it.
What does Epsom salt do for plants?
Epsom salt gives plants magnesium and sulfur. Magnesium is the center of the chlorophyll molecule, so a real deficiency causes yellowing between leaf veins, starting on older leaves. Epsom salt only fixes that specific deficiency, not other causes of yellow leaves.
What plants like Epsom salt?
Tomatoes, peppers, and roses use more magnesium than most plants, so they’re the most likely to benefit, but only in magnesium-poor soil. Garden studies found no extra yield or growth from Epsom salt on these plants when the soil already had enough magnesium.
How much Epsom salt should you use for plants?
Use the amount your soil test recommends. Without a test, a common home rate is 1 tablespoon of Epsom salt per gallon of water, applied no more than once a month during the growing season. Never sprinkle it on heavily.
Can too much Epsom salt kill plants?
Yes, too much Epsom salt can kill plants. Excess magnesium builds up as salt in the soil, burns roots and leaves, and blocks plants from absorbing calcium and potassium. Flush overdosed pots with plain water several times.
Does Epsom salt help tomatoes with blossom-end rot?
No, Epsom salt doesn’t help blossom-end rot. Blossom-end rot is caused by a calcium shortage, usually from uneven watering, and extra magnesium can make it worse by blocking calcium uptake. Keep tomato soil evenly moist instead.
Is Epsom salt good for houseplants?
Epsom salt is rarely needed for houseplants, because most potting mixes and houseplant fertilizers already contain magnesium. In pots, extra salts build up quickly and burn roots. Use a balanced houseplant fertilizer instead.
Do succulents like Epsom salt?
No, succulents generally don’t like Epsom salt. They grow best in lean, fast-draining soil, and extra salts can stress roots and burn leaves. Focus on bright light and careful watering instead.
What can I use instead of Epsom salt?
Instead of Epsom salt, use a balanced fertilizer that contains magnesium, or add dolomitic lime if your soil test shows both low magnesium and acidic soil. Compost also adds magnesium and other nutrients slowly and safely.
