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. Farmers were quick to discover that Epsom water had “magical” healing properties, and its fame quickly travelled far and wide.

What is Epson Salt?

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.

What does the magnesium in Epson Salt do?

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.

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.

Why do Cannabis plants need magnesium?

The Cannabis plants need magnesium because it helps them to take phosphorous, nitrogen, and sulfur from the soil. If your Cannabis crop has yellow leaves, you definitely should give them magnesium from Epsom salts. Before using any of the supplements you should know the right diagnose of your plants because you do not want to burn the plants with supplements. When you see yellowing leaves with green veins on your crop give a magnesium supplement. Magnesium helps the creation of chlorophyll, which is the most important for the photosynthesis, and you can start with small doses of Epsom salts. The Epsom salts are a crucial key for seed production and germination.

Why is sulfur necessary for weed plants?

The sulfur together with magnesium is multi-vitamin for your plants; the higher level of sulfur will produce more amino acids, enzymes, and vitamins for the crop. The sulfur is the side helper for the production of the chlorophyll, and with sulfur, your garden will always have green, and healthy leaves. This is very important for the long-life plants which are exposed to environmental stress. If you live in the area with the ’hard’ water you must give your plant extra magnesium.

How to Use Epsom Salts to Supplement Soil

You can use Epsom salts if you are growing both in pots or in beds, just do not use these salts if you are already using dolomite lime. The soil responds the best when you apply a foliar spray or full watering with Epsom salts. The soil in the Pacific Northwest is not rich with magnesium and you must treat it with Epsom salts.

In a gallon of soil goes one teaspoon of salts and your substrate is ready for use, before the planting. You can also use Epsom salts when your plants are a few inches tall then you can feed them with Epsom salts water. The cuttings will grow faster if you prepare the soil with the Epsom salts.

Dosage for Dissolving Epsom Salts in Water

Mix one or two tablespoons of Epsom salts with a gallon of warm water and give to your plants every four to six weeks. If you are using a foliar spray, just mix one tablespoon in one gallon of water, and spray your Cannabis plants at the beginning of each cycle. Do not spray your plants during the first week of flowering, or while the lights are on. The effect of spraying will be stronger if the temperature in the room is much cooler.