Epsom salt for plant helps improve flower blooming and enhances a plants green color. It can even help plants grow bushier. Epsom salt is made up of hydrated magnesium sulfate , which is important to healthy plant growth. good dose of magnesium. If your plants are needing a boost, dissolve about one to two tablespoons of epsom salt in a gallon of water. Pour at the base of the plant and allow the watersalt solution to soak into the ground. Repeat throughout the season as necessary. Soil incorporation , broadcast 1 cup per 100 square foot, mix well into soil before planting. At planting time when planting seedlings or new plants, dig a hole and place about 1 tablespoon of epsom salt in the bottom of hole and cover with a thin layer of dirt, place the plant in the hole and finish planting. Peppers spray your peppers at bloom time. Combine 1 tablespoon of epsom salt with a gallon of water. Ten days later, repeat the foliar spray again. Tomatoes tomatoes can benefit from epsom salt every 2 weeks. Apply 1 tablespoon diluted in water per foot of plant height per plant. Roses. Soak unplanted bushes in 1 or 2 cup of epsom salt per gallon of water to help roots recover. Then add a tablespoon of epsom salt to each hole at planting time.