To mix Epsom salts for tomatoes, gather measuring cups and spoons, buckets, gardening tools and a spray bottle. Some gardeners use Epsom salts once, while others apply it many times during the course of the growing season. Adjust usage as needed based on the appearance of the tomato plants and fruit.
- Apply Epsom salts before planting
Before setting tomatoes plants out, mix 1 tablespoon of Epsom salts into the soil. Dig the hole for the tomato plant, mix soil and salts in the bottom, and plant the tomato. Water normally.
- Use when flowering begins
Once the tomato plants begins to flower, add up to 1/2 cup Epsom salts to the soil. Gently hoe to mix in, and then water for 10 minutes. Alternatively, mix 1 tablespoon Epsom salts with 1 gallon water, and spray onto the plant. This solution can be applied twice in a month, or the Epsom salts can be increased to 2 tablespoons and applied once a month.
- Apply late in the growing season
As the tomatoes grow and produce fruit, magnesium in the soil can wane. Spray the plant with a solution of 1 to 2 tablespoons Epsom salts to 1 gallon of water, following the same guidelines as above. Another option is to add 1 tablespoon per each foot of plant height to the soil next to the plant. This side dressing option should be repeated every six weeks, as the absorption rate is slower in this form than in the solution form.