Aside from the anecdotal evidence about human benefits, Epsom salt does seem to help plants. Generations of gardeners have said it helps their plants grow bushier, produce more flowers and have better color. It's also said to help seeds germinate and repel slugs and other garden pests.
Epsom salt can improve the blooms of flowering and green shrubs, especially evergreens, azaleas and rhododendrons. Work in one tablespoon of Ultra Epsom Salt per nine square feet of bush into the soil, over the root zone, which allows the shrubs to absorb the nutritional benefits.
For a general Epsom salt supplement that can be used in the garden and on houseplants, use two tablespoons of Epsom salt per gallon of water, and use this to water your plants once each month in between regular watering.
Adding Epsom salts to soil that already has sufficient magnesium can actually harm your soil and plants, such as by inhibiting calcium uptake. Spraying Epsom salt solutions on plant leaves can cause leaf scorch. Excess magnesium can increase mineral contamination in water that percolates through soil.
Prevent Fungal Disease
MAKE IT: Mix 1 teaspoon of baking soda and 2-3 drops of liquid soap in 1 liter of water. Spray the solution on the infected plants. Baking soda helps the plants become less acidic and prevents fungal growth.
Use Epsom Salt for Big Garden Yields
To grow huge flowers (and lots of veggies), I use Epsom salt for my garden. Mix 6 tablespoons Epsom salts and 6 tablespoons Miracle-Gro fertilizer in the hand sprayer attached to my garden hose, says Birds & Blooms reader Juanita Scalia.
If your plant's leaves are turning yellow, it might have a sulfate deficiency. If your plant's leaves are turning yellow but the veins remain green, it might have a magnesium deficiency. Epsom salts are a great solution for both of these problems.
Coffee grounds have a high nitrogen content, along with a few other nutrients plants can use. In compost, they help create organic matter that improves the ability of soil to hold water.
Alternatively, some sources suggest adding the salts directly to the soil: 1 teaspoon of salts for every foot of plant height. Some bloggers suggest adding Epsom salts to your houseplants every month, monitoring subtle changes in leaf vibrancy and growth.
Most plants can be misted with a solution of 2 tablespoons of Epsom salt per gallon of water once a month. For more frequent watering, every other week, cut this back to 1 tablespoon (15 mL). With roses, you can apply a foliar spray of 1 tablespoon per gallon of water for each foot (31 cm) of the shrub's height.
It is perfectly safe for plants when properly diluted and used in moderation. Adding hydrogen peroxide to water promotes better growth in plants and boosts roots ability to absorb nutrients from the soil. Diluted 3% peroxide adds needed aeration to the soil of plants and helps control fungus in the soil.
Which plants shouldn't you try this with? Don't add eggshell fertilizer to plants that prefer acidic soil, like blueberries. Ericaceous plants such as mountain laurel, pieris and azaleas also fall into that category. In extreme cases, low acidity for plants could impact their overall health and/or the resulting crop.
However, Epsom salt can still help a tomato plant where the soil is too alkaline or one that has been overwatered. In this way, it helps boost absorption as well as improving photosynthesis in the existing foliage.
Like sulphur, cinnamon is a natural fungicide that helps most plants root, while inhibiting the spores that cause rot in stem cuttings. Dip prepared plant stems in cinnamon and push them into the soil. It's an effective rooting hormone that's easy to use and inexpensive.