Herbies editorial team Herbies

What Is Epsom Salt And Why Is It So Important For Cannabis Plants?

Last updated: 16 July 2025

epsom salt cannabis

There are many different ways to modify your garden into a more organic, natural environment for your cannabis plants to live in. Using natural ingredients is one way to ensure the best quality plants, and luckily for you, there are plenty of natural sources for your plants to get all the nutrients they need. Here, we will be looking at Epsom salt for cannabis growth and what it can do to benefit your growing ambitions.

Origins Of Epsom Salt

what does epsom salts do for plants

Epsom salt, the nickname given to magnesium sulfate, is a compound that was discovered in underground springs in the town of Epsom, England. However, these are different from Epsom salts that are used for gardening, as they contain aromas and perfumes not suitable for plants.

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Why Should I Use Epsom Salt For Cannabis?

epsom salt for weed

Using Epsom salt for cannabis plants is extremely important for those who want to begin implementing more organic ingredients in their gardening habits. When using Epsom salt for weed, it’s almost impossible to overfeed your plants. At the same time, it provides them with a healthy dose of micronutrients that are crucial for strengthening their cell strength and overall immunity.

Disclaimer: Cannabis cultivation laws vary by region. This information is intended for use in areas where growing cannabis is legal. Please check your local laws before proceeding.

A Natural Source Of Nutrients

Epsom salt is an excellent addition to your gardening routine, as it’s a natural source of two essential nutrients for cannabis plants: magnesium and sulfur. Using Epsom salt in cannabis cultivation can help gardeners reduce their dependence on synthetic nutrient supplements or specialized fertilized soils. By incorporating organic inputs like Epsom salt into your feeding schedule, you’ll promote healthier soil and support a balanced, vigorous plant life cycle.

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The Importance Of Magnesium in Epsom Salt

epsom salt for cannabis

Epsom salt is a natural source of magnesium – one of the most important nutrients for a plant’s development, as it supports the uptake of essential elements like nitrogen, phosphorus, and potassium. Magnesium also plays a key role in the production of chlorophyll – the pigment responsible for cannabis plants' ability to absorb sunlight. This process enables photosynthesis and helps strengthen cell membranes, contributing to overall plant vitality. In short, maintaining adequate magnesium levels is crucial for the healthy, vigorous growth of cannabis.

Why Do Plants Need Sulfur?

how to apply epsom salt to plants

Sulfur is the essential basis for your plant’s immune system. Sulfur facilitates the production of amino acids, enzymes and vitamins in your plant, all of which aid in the healthy growth of a plant and build up its immune system. In other words, a healthy base of sulfur in your garden will help prevent your plants from getting sick. Sulfur is also essential for your plants to create chlorophyll. Most importantly, it works together with magnesium to secure the plant's uptake of nitrogen, phosphorus and potassium, or NPK – the most essential nutrients to a cannabis plant’s survival.

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Bring Epsom Salts Into Your Garden To Prevent Deficiencies

epsom salt for weed plants

Now that we understand why magnesium sulfate, or Epsom salt, is so beneficial to plant health, we can apply this knowledge to our own cannabis grow operations. Incorporating Epsom salt into your feeding schedule is an excellent way to prevent or correct magnesium deficiencies, which can negatively impact bud development, as well as sulfur deficiencies, which may stunt growth and lead to leaf discoloration.

The Right Time To Incorporate Epsom Salt

epsom salt for cannabis plants

You can begin using Epsom salt early in your cannabis plant’s life cycle, once the seedlings are just a few inches tall. However, it’s best to discontinue Epsom salt applications during the first week of flowering, as it may interfere with bud formation. In general, providing sufficient magnesium and sulfur throughout the vegetative stage will help ensure strong growth and high yields at harvest.

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How Much Epsom Salt To Apply And How?

epsom salt and marijuana

You can use Epsom salt for weed growth as a topical foliar spray when diluted with water, or add Epsom salts directly into the soil or substrate. It’s a great way to prevent or treat magnesium or sulfur deficiency.

The ideal amount of Epsom salt for cannabis plants depends on the way you're using it. If you're spraying your plants, mix one tablespoon with 5 liters (1.3 gallons) of warm water. If you're adding Epsom salt to the soil, mix one teaspoon in 3.7 liters (1 gallon) of soil.

Start Using Epsom Salt Now

Epsom salt is an excellent way to ensure proper nutrient levels in your garden by using natural sources for organic ingredients. As proper levels of magnesium and sulfur are critical to healthy cannabis plants, using Epsom salt for cannabis can be considered a necessary addition to your gardening shed. Whether you want to start a new substrate or are looking for a natural way to cure some nutrient deficiency, Epsom salt and marijuana makes for the perfect team. To start your cannabis journey, look for high-quality marijuana seeds to pair with the benefits of Epsom salt, ensuring a strong and healthy grow.

Disclaimer: Before purchasing or growing cannabis seeds, ensure that cannabis cultivation is legal in your region. It is the customer's responsibility to comply with local laws.

Herbies Head Shop expressly refuses to support the use, production, or supply of illegal substances. For more details read our Legal Disclaimer.

Den
How often should I add water to water?
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Herbies
Hello, Den, thank you for your comment! Do you mean how often you should add Epsom salt to water? You can add Epsom salt to water with every watering based on your schedule. You can start when the plants are just a few inches tall, but please avoid adding it during the first week of flowering!
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Newbie
When watering a plant after it has sprouted, should you avoid getting water on the leaves? Essentially water the ground not the plant?
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Reply
Herbies
Hello! Yeah, you should always prioritize watering the soil and avoid wetting the leaves and buds to prevent mold, mildew, and other issues
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Benjo
How often can I spray the mot Epsom salt? My water has about 75g calcium and 11g magnesium, so there is too little magnesium. How is it when watering with it? I don't really understand how to use it. What would you recommend for the value of seedling, vegetation, flowering
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Herbies
Hello, Benjo! Thank you for your comment, it's greatly appreciated! You can start spraying water mixed with Epsom salt once a day every day within the beginning of each lifecycle, starting when the plants are just a few inches tall. However, please cease using Epsom salts during the first week of flowering!
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Ginga kiwi
How often Do u use epsom salts is it every water or what please
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Herbies
Hello Ginga, you can use epsom salt with every spraying within the beginning of each lifecycle though it's recommended to avoid using it during the first week of flowering
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Christofo
Thank you very much for the information, I just had a magnesium deficiency in the leaves of the plant and from the second day of application they started to improve with Epsom salts, I used half a teaspoon for 2 liters of water in controlled PH.
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Christo
Foliar feeds are usually acidic in nature.
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The other guy
Very informative article thanks
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Shonuff
Brand doesn't matter. Just ensure it is pure epsom salt. Nothing with scents
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WW
Shonuff, when you say nothing with scents is that including stuff like hemp seed oil and White Thyme & Bergamot. I have bought Dr. Teals Pure Epsom SaltSoaking Solution, Cannabis Sativa Hemp seed oil with essential oil blend. I don't want to use it if it's going to mess with my plants.
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