Epsom Salt In The Garden

Bag Of Epsom Salt
Bag Of Epsom Salt

Occasionally, I hear someone recommending that gardeners use Epsom salt. I’ve even seen it on television were some supposed master gardener will come out and say you should use Epsom salt for this or that. So, having been recently asked, once again, about Epsom salt, I thought I would put down a few notes which may be helpful to fellow gardeners.

What is Epsom Salt?

  • Epsom salt is a very simple crystalline chemical mix magnesium, sulfate, and trace amounts of water.

Is Epsom Salt A Fertilizer?

  • Actually, Epsom salt would not be considered a fertilizer. It could be regarded as a nutrient as common garden plants require some magnesium, but it is not one of the three constituents of fertilizer, which are nitrogen (N), phosphorus (P) and potassium (K) (NPK). Epsom salt has no measurable quantity of nitrogen (N), phosphorus (P) and potassium (K)  (NPK)

Magnesium Deficiency in Plants

  • Magnesium deficiencies can occur in soils, but it’s not usually much of a problem. And the only really trustworthy way to know if your garden soil has a sufficient magnesium unit is to have a soil test performed.
  • Generally, if you have been taking reasonable care of your garden and adding some soil amendments such as compost, you shouldn’t have much of an issue with magnesium deficiencies.

Does Epsom Salt Control Pests?

  • The short answer is no, nor does it repel the usual garden pests.

Does Epsom Salt Control Plant Diseases?

  • Here, also, the short answer is no; Epsom Salt does not control or kill any common garden disease.

Does Epsom Salt Make Plants Grow Better?

  • Also, no; unless your soil has a magnesium deficiency and Dolomitic lime may actually be a better solution; especially, when combined with some fresh compost.

Preventing Blossom End Rot (BER)

  • Blossom End Rot is a calcium deficiency coupled with an improper watering regiment. Blossom End Rot (BER) is not a magnesium deficiency. Adding Epsom salt, magnesium, will not fix the problem.

Should You Use Epsom Salts?

  • I would very strongly recommend a soil test first if your soil test shows that you have a magnesium deficiency:
  • Consider using Dolomitic lime, rather than Epsom salt. However, if your soil test indicates a magnesium deficiency and your soil PH level support it.
  • If you choose to use Epsom Salt to address the magnesium deficiency, you will need to use it in moderation and perform multiple, regularly scheduled, applications throughout the growing season.


While some gardeners do use Epsom salts, there are other better alternatives for providing magnesium. Therefore, I find that I cannot in good conscience recommend it to a fellow gardener.  If you feel that you must use Epsom salt, then plan it carefully and remember that more is not always better.

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