Using Epsom salt in gardening is not a new concept. This “best kept secret” has been around for many generations.

Magnesium allows plants to better take in valuable nutrients, like nitrogen and phosphorus. It also helps in the creation of chlorophyll, which is vital for photosynthesis. In addition, magnesium greatly improves a plant’s ability to produce flowers and fruit. If the soil becomes depleted of magnesium, adding Epsom salt will help; and since it poses little danger of overuse like most commercial fertilizers, you can use it safely on nearly all your garden plants.

Usage :

Mix one table spoon of Epsom salt with 1 liter of water and spray to your plants 

Benefits 

1. Encouraged growth: Magnesium is essential for plants because it increases chlorophyll production. Chlorophyll creates green color in the plant's leaves and assists in plant growth. A boost of magnesium encourages seed germination and fast growth by strengthening plants’ cell walls.
2. Root shock prevention: When you’re transplanting seedlings or full-grown plants, roots can become stressed, causing them to stop growing. Known as root shock (or transplant shock), your plants may wilt or have yellowing leaves, among other signs. Epsom salt can prevent root shock by increasing chlorophyll production and helping the roots absorb more nutrients.
3. Improved flavor: The more chlorophyll a plant produces, the more sugar it produces, which results in sweeter and more flavorful fruits and vegetables.
4. Pest control: To deter bugs like beetles, mix one cup of Epsom salt with five gallons of water, add the mixture to a spray bottle, and apply it to leaves. To control slugs, sprinkle the dry salt around the base of the plant.