Does Epsom Salt Help Roses and Other Flowering Plants Bloom Better

Epsom salt, which is a mineral made up of magnesium and sulfate, is often touted as helping with plant growth and flowering. But does it work? As with most gardening questions, the answer is “it depends”. It has potential to help your flowers and vegetables IF your soil is low in either magnesium or sulfate. Where I live, in semi-arid Montana, magnesium is plentiful in the soil and so deficiencies are very rare. Sulfur deficiencies are also rare, at least in gardens, because compost, which is often added, is fairly high in sulfate (the available form of sulfur) and removal in vegetables (except brassicas) is fairly low. In places with more precipitation, like the southeast U.S., soils are more likely to be deficient in either magnesium or sulfur because both are more likely to have leached out of the soil.

So how can you know if your plants are likely to benefit from Epsom salts? The best ways are to either soil test or tissue test. If the results indicate deficiency of either, then Epsom salts might be worthwhile, but keep in mind that salts can hurt germination, emergence and growth, so make sure you’re not adding more than recommended and avoid applying at seeding time when plants are more vulnerable to salt damage.