Epsom Salts – The Gardeners Friend

Epsom salt is the gardeners friend twice over – or maybe I should say three times.

First and second, Epsom salts contain two important macro-nutrients plants need to thrive, not merely survive. Third, gardeners can use some Epsom salts in the bath to soak away aches after a long day working in the garden.

Why Plants Might Need Epsom Salt

Epsom salt is a simple chemical compound of magnesium and sulfur linked together as magnesium sulfate. Both magnesium and sulfur are considered macro-nutrients – they are crucial to healthy plant life. Micro-nutrients are also inportant, but a plant can survive without them. More on micro-nutrients in a future post. When sulfur is in sulfate form, it is available to biological organisms.


Magnesium plays a crucial role in photosynthesis since it is the center of every single chlorophyll molecule critical for the plant to make it’s food. Magnesium is also needed for growth – to make cell walls, and for seed seed germination.

Sulfate helps the plant make the chlorophyll molecules in the first place, and helps release other soil bound minerals. Indeed, sulfur is occasionally used to help break down caliche soils. More about caliche in my YouTube video – here.

Magnesium deficiency is rare in most average Southwest soils. It is most likely in sandy soils or if you over-water your plants.

How to Safely Use Epsom Salt

First, like any plant nutrient, too much can harm the plants you wish to help!

It is better to use just as much as is recommended here. If you think your plants need more, consider getting a soil test.

You can purchase Epsom salts at the pharmacy, and it works fine for plants. For garden use, check your local hardware store for “non-human-use” grade that will save you money.

Epsom Salt For Annual Plants

For the vegetable garden, scatter one cup of Epsom salt per 100 square feet, and work or water it into the soil before seeding or planting. For flower beds and container plants, dissolve one tablespoon of Epsom salt per gallon of water, and use this to water once a month.

Epsom Salt For Landscape Plants

All shrubs – but especially large evergreens such as honeysuckle, Texas rangers, yellow bells, and woolly butterfly bush – benefit from one tablespoon of Epsom salt per bush once a year – in spring (add this to your March Garden Calendar). Sprinkle the salts around the drip line of the shrub and dig or water it into the soil.

Treat trees the same way. They can use more. Plan on one Tablespoon per square foot of ground shaded by the tree at noon. Good news – even legume trees will like this. You shouldn’t give legumes nitrogen fertilizer but some Epsom salts work can lend a hand if they need it.

Thanks for reading!


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