Can Epsom Salt Help Keep Your Roses Blooming Into Fall?

Your grandma or a neighborhood rose enthusiast may swear by fertilizing roses with epsom salt. Many gardeners give roses a monthly drench of epsom salt believing it leads to more new growth, more flower buds, and greener leaves. Some may even claim that epsom salt will help keep roses blooming in the fall.

There isn’t much to back up this claim, though. If you want your roses to bloom for as long as they can, deadheading and regular watering is the best approach to keep them flowering well into the fall.

Does Epsom Salt Help Roses Bloom?

Epsom salt is the common name for magnesium sulfate, and magnesium is a micronutrient that plants need. According to the Clemson Cooperative Extension Home and Garden Information Center, magnesium is used by plants “in carbohydrate transportation, photosynthesis, and the synthesis of proteins.” The American Rose Society also notes it “plays a role in strengthening plant cell walls, allowing the plant to take in the nutrients it needs.”

Leaves may turn yellow on roses that have a deficiency. “The first symptom of a magnesium deficiency in roses is a reduction of leaf size, followed by entire leaves being chlorotic with yellow between veins,” the American Rose Society says.

But what about increased flowering? A horticulturalist at Washington State University Extension found just one example of a study on an apple tree that flowered more when the foliage was sprayed with epsom salt. The apple tree was “particularly sensitive to magnesium deficiency” and “thus, it is not surprising that flowering may increase once a nutrient deficiency has been relieved.”

Roses only need trace amounts of magnesium, and most garden soils have plenty. Plus, the Clemson Cooperative Extension notes that regularly drenching your soil with epsom salt could create a saline environment that actually interferes with the uptake of nutrients like calcium. Our conclusion? Before using epsom salt, it’s best to get your soil tested with your local extension office.

How Can I Keep My Roses Blooming In Fall?

The best way to keep your roses blooming in fall is by deadheading them. Removing spent flowers will encourage roses to continue blooming instead of forming rose hips.

You also want to keep roses well-watered during dry spells so they’ll keep flowering. Refresh the mulch around your roses if needed to conserve moisture and regulate soil temperature.

Your rose bushes need to harden off before winter, so you don’t encourage them to produce soft, green growth. Skip fertilizing roses in fall altogether unless you live in a frost-free climate. The general guidance is to stop fertilizing about eight weeks before the first frost in your area. This will allow your rose to go into a natural dormancy and rest over the winter before it blooms again next season.