epsom salt for pot plants

Epsom Salts: a natural hack to grow healthy cannabis plants

Epsom salt is the best and most natural way of adding magnesium and sulfur to your cannabis plants. The benefits are astounding and there is little risk of overfeeding. Find out why you should use Epsom salt in your next grow.

Epsom salt is the nickname given to magnesium sulfate. The name comes from the spring water of Epsom, England. Farmers were quick to discover that Epsom water had “magical” healing properties, and its fame quickly travelled far and wide.


Epsom salt looks very much like coarse kitchen salt. But make no mistake, they are entirely different in molecular terms. Epsom salt is also used in health and beauty products in the form of bath salts, exfoliators, muscle pain-relievers, migraine-relievers, and those that treat cold and flu symptoms. Be cautious not to use these forms of Epsom salts to feed your plants, as they are often mixed together with all sorts of dyes, alcohols, aromas, and other ingredients that are likely to damage your cannabis plants. You will easily find the right product in any garden store, and even in pharmacies and health food stores.

Epsom salt is a fantastic and completely natural way of giving your cannabis plant an extra boost of both magnesium and sulphur, with the added benefit that you really can’t go very wrong with it. Excess feeding of these micronutrients will not have a negative effect on your plants. It is almost impossible to oversaturate the soil over time. Epsom salts also can be used in hydroponic systems; though here, you should be particularly mindful of potential pH swings.

It is very easy to use, easy to source, and cheap to boot. It is highly soluble in water, so it doubles as a great foliar spray. With the evermore urgent pursuit of completely organic ways of growing great weed, Epsom salts deserve an honourable spot in your arsenal of all-natural and environmentally conscious products.


There is no major difference in the magnesium found in Epsom salts as opposed to say, Cal-Mag supplements. The major difference is Epsom is an all-natural product while bottled supplements are usually petrochemical-derived.

High-performing crops have a tendency to exhibit some sort of deficiency if nutrition is not perfectly tailored. Cannabis certainly is one of these crops. In particular, plants grown hydroponically tend to exhibit a higher propensity for magnesium deficiency. Even is soil, certain strains seem to complain and demand a considerable boost of this micronutrient to maintain lush green foliage and vigorous growth.

Magnesium also facilitates the uptake of nitrogen (N), phosphorous (P), and potassium (K). Should a magnesium deficiency occur, it is easy to detect due to the characteristic yellowing of the leaves, except in the veins. This contrasts with the typical nitrogen deficiency, where the entire leaf turns yellow. Magnesium deficiency also tends to manifest first in the lower sections of the plant, with the yellowing leaves curling slightly upwards.

Magnesium is also highly implicated in photosynthesis, as it facilitates the creation of chlorophyll. It also strengthens cells walls, which are responsible for plant vigour and steady growth.

Magnesium is essential to achieve those superbly high yields. To form big buds, you need a healthy dose of this element. Furthermore, magnesium is essential for seed formation, too.


Sulphur is one of the building blocks of the plant’s immune system. It is also what gives garlic and onions their pungent tinge on the tongue. For cannabis, it works together with magnesium to increase the uptake of NPK, and is implicated in the production on enzymes, amino acids, and vitamins.

Chlorophyll also requires sulphur; but an area where this element is of particular interest is when keeping mother plants. Sulphur helps to promote longevity and reduce environmental stress. Mother plants are kept in veg for inordinate amounts of time. As cannabis is not a perennial species, this can pose a nutritional challenge, and Epsom salts certainly alleviate the issue of constant maintenance.


Epsom salts are very forgiving. As mentioned, it is difficult to overdo. But as with all things, little at a time goes a long way. These salts may be cheap, but costs do add up.

General rule of thumb would say 1 tablespoon per 5 litres of water can make for a great foliar application every other week. Difficult soils that have a pH above 7 will naturally lock out calcium and magnesium ions, so amending with some Epsoms salts is a great idea.

A more diluted version of Epsom salt water can also be used to help with seed germination, and even to help clones root faster. Harder-to-clone strains have been known to have a higher success rate by both misting and adding this mix to the actual cutting.

In the case of treating a deficiency, you should allow 3 to 4 days before evaluating the results by verifying new growth patterns and recovery from the less-affected leaves. More-affected leaves may well be scarred by magnesium deficiency and never fully recover.


As a final note, agricultural-grade Epsom salts are of great benefit to humans too. It is the base ingredient to fancy bath salts and many health and cosmetic products. Feel free to experiment with some of its known applications, should you need some relief from various common ailments. Now you and your plant can bond even further by using something in common.

Epsom salts get their name from the spring water of Epsom, England. But what exactly do they do for cannabis plants?

10 Ways to Use Epsom Salts in the Garden

Learn how magnesium-sulfate can boost plant health, deter pests, and bring a host of other benefits to your lawn, flowers, veggies, and more.

You’re probably familiar with the amazing, healing properties of Epsom salts. But did you know these minerals are a powerful superfood for your garden too? Inexpensive, natural, and non-toxic when used correctly, Epsom salts—the common name for the magnesium-sulfate compound (MgSO4)—can be a great boon to virtually anything you hope to grow. Magnesium-sulfate (which looks like ordinary table salt) can help increase nutrient absorption in plants.

Before working with Epsom salts in the garden, be aware of some precautions. Agricultural or technical grade Epsom salts are intended for garden and outdoor uses but only brands marked “USP” are suitable for humans, having been tested and certified by the FDA and United States Pharmacopeia (USP). Also, despite its overall safety, Epsom salts have natural laxative properties, so be sure to keep bulk salts away from children and pets. Magnesium-sulfate is absorbed through the skin as well, so wear gloves when applying it to your plants. Finally, it’s also wise to test your soil first to learn what minerals are low or lacking; use Epsom salt in the garden only if the soil tests low in magnesium.

Clear these safety concerns and you’re bound to find that, unlike most types of chemical fertilizers, Epsom salts will not build up in your soil or poison your groundwater, yet will yield stronger seedlings, more bountiful blooms, tastier fruits, decreased pest damage, and increased resilience. Here are 10 simple, potent uses for Epsom salts every gardener should know.

1. Give Seeds a Better Start

Magnesium boosts seed germination by strengthening cell walls and providing increased energy for growth. Sulfur is easily lost during the germination process, so apply a drench of one tablespoon of Epsom salts for every gallon of water to the soil after seeding. Alternately, you can mix one tablespoon of Epsom salts into each hole before planting seeds. For grass seeds and wildflowers, sprinkle one cup Epsom salts per 100 square feet, blend into the soil, and water thoroughly. Reapply an Epsom salt drench to seedlings every month during growing season.

2. Increase Nutrient Absorption

Scientific tests indicate that magnesium-sulfate can increase cell uptake of key minerals, including nitrogen, phosphorus, and sulfur. In one recent study, testers in five states gave pepper plants a standard drench of one tablespoon Epsom salts to one gallon of water, twice a month, and a majority of the treated plants showed thicker foliage and larger vegetables.

3. Prevent Root Shock

Transplanted roots need tender care. To prevent root shock, which causes wilting and leaf discoloration, mix one tablespoon of Epsom salts for every one gallon of water and apply to the roots of newly re-potted plants until saturated. Or try adding one to two teaspoons of dry salts directly to the hole before transplanting a bush or flowers. After tamping down the soil, water thoroughly.

4. Deter Pests Naturally

Instead of using plain table salt to dehydrate and kill snails and slugs, banish the pests with Epsom salts and you’ll give roots and blooms a boost in the process. For general pest control, mix one cup of Epsom salts with five gallons of water and spray onto foliage. For slug and snail control, sprinkle dry Epsom salts in the garden around the base of plants.

5. Add Vibrancy

Mineral deficiencies can interfere with photosynthesis, leaching green color from leaves and interfering with nutrient absorption. If more mature foliage is turning yellow and curling, this may indicate a magnesium deficiency. Try a foliar spray of one tablespoon of Epsom salts mixed with four cups of water for each foot of plant height. Magnesium absorbs well if applied directly to the leaves.

6. Boost Flavor

Every month during growing season, mix one tablespoon of Epsom salts to each gallon of water and apply liberally to the roots of fruit and nut trees, grape vines, and berry patches. Another technique is to apply two tablespoon of dry salts over a nine-foot root-bed area, three times a year.

Sweet peppers and tomatoes also benefit from adding some Epsom salt to the garden soil. Before planting seeds, add one to two tablespoons of Epsom salts to the soil of each hole. During the growing season, apply a foliar spray of two tablespoons of salts to each gallon of water. Apply to leaves once a month.

7. Grow a Lush Lawn

If your soil tests positive for magnesium deficiency, Epsom salts will help your lawn achieve maximum growth and lushness. The Epsom Salt Council recommends applying three pounds of salts for every 1,250 square feet of lawn with a spreader. Sprinkle the salts lightly, then water your lawn with a hose or sprinkler system.

8. Heal Your Houseplants

Epsom salts are pH neutral and gentle on plants, including potted houseplants. To boost nutrient intake, mix two tablespoons of Epsom salts with one gallon of water and spray onto leaves, rather than onto the roots, for maximum absorption. Alternately, add the salts directly to the soil: one teaspoon of salts per each foot of plant height. Try adding Epsom salts to your houseplants every month, monitoring subtle changes in leaf vibrancy and growth.

9. Remove Tree Stumps

Professional stump removal services can cost between $60 and $350, depending on the size of the trunk. For a do-it-yourself means of removing a tree stump, though, you can enlist Epsom salts to kill the remains of a cut tree first. Bore holes all around the top of the stump with an electric ½-inch drill bit; these holes should be about half the depth of the stump and spaced a few inches apart. Then, pour dry Epsom salts into the holes and slowly add water to moisten, but not saturate, the salts. Cover the stump with a tarp to repel rain and ensure the drying process. The salts will dehydrate the wood over several weeks, and as the wood dries out, you’ll be able to chip away most of the stump with an ax and soon dig up and dispose of the root system.

10. Produce Bountiful Roses

The magnesium in Epsom salts benefit both new and established rose bushes, helping to supplement a slow-release rose fertilizer containing nitrogen, potassium, and phosphorus. Before planting a new rose bush, add one tablespoon of Epsom salts to the bottom of each hole. For established roses, add one tablespoon of salts for every gallon of water and spray foliage when plants begin to leaf in spring and once again during flowering.

Learn how a sprinkling of epsom salts in the garden can boost plant health, deter pests, and bring a host of other benefits to your lawn, flowers, & veggies