Roses and Epsom salt

Rose photo by Joanne Young
Roses benefit from applications of Epsom salt. (Photo by Joanne Young)

If you’ve seen the gorgeous cover of the summer issue of Garden Making, you’ll know why roses are on my mind. I’ve already been out to purchase Epsom salt from the drugstore (and my supermarket carries it, too); now I’ll head into the garden with a measuring cup to deliver treats to these stunningly beautiful plants.

It’s still too early to fertilize roses that haven’t yet sprouted new stems and leaves. Feeding plant nutrients (nitrogen, phosphorus, and potassium) to roses before they have the means to process the foods into carbohydrate energy can burn tender roots and cause shock. But this is an ideal time to provide a dose of Epsom salt to strengthen the shrubs and encourage them to grow more woody canes, which will result in increased flowering potential and better winter hardiness.

Epsom salt is a natural mineral compound containing magnesium and sulfur, two natural elements roses use to trigger new wood (called basal breaks), sprouting low down near the shrub crown. This new wood adds to the structure of the plant, increasing its capacity to carry flowers, and benefiting the health and durability of woody canes.

Before planting a bareroot rose, soak its roots in a bucket of one-half cup of Epsom salt per gallon of water overnight. Use the soaking water to water the shrubs into their holes. When planting a potted rose, work one-quarter cup (60 mL) of Epsom salt into the soil in the planting hole, and scratch another one-quarter cup in the soil over the root zone in midsummer. Established roses should receive one-half cup (125 mL) spread in a circle around the shrub and lightly scratched into the soil over their roots. (For more information about gardening with Epsom salt, see this article from the National Gardening Association:

And whatever Epsom salt is left over from feeding to roses can, of course, go into your bath water!


  1. Adrien Gallant says

    Hello Judith, good article on Epsom salts. I was aware of the benefits of Epsom salts on peppers and tomatoes but this was the first time that I had seen an article on the benefit on roses for home gardeners. Commercial hydroponics growers use large amount of Epsom salts to grow peppers and tomatoes right here in Ontario. I am also aware that large amounts of the fertilizer are used by commercial growers to grow roses in Kenya for the Dutch market. Ideally, Epsom salt should be used in soluble fertilizers such as Miracle Gro however, adding too much magnesium in a soluble fertilizer would react with the phosphorus and precipitate the product in solution.
    Best Regards,
    Adrien Gallant P. Ag.

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