Growing mint hydroponically is an alternative solution for those who, for various reasons, do not wish to grow mint directly in their gardens or in potting soil. Mint is well-suited for hydroponic growing and is, in fact, one of the first plants to be grown hydroponically in England in 1699, according to the University of Arizona Department of Plant Sciences. Fresh mint is used in a number of food recipes, as well as several beverages. When harvesting your mature mint leaves, hold the stem of the plant with one hand, while removing the leaf with the other. This will help avoid damage to the plant itself.
Building the Hydroponic Garden
Choose a container capable of holding a minimum of 5 inches of nutrient solution. Depending on the desired size of your hydroponic garden, a plastic kiddie pools work well for large gardens, while storage containers are a good choice for growing mint on a smaller scale, according to University of Florida Extension.
Trim sheets of plastic foam with a handsaw or serrated knife to fit the garden container. The sheets should cover most of the surface area of the container, but still float freely in the nutrient solution.
Create holes in each plastic foam sheet, using a hole saw. Use a 2 1/2-inch hole saw for 3-inch net pots, or a 1 3/4-inch hole saw for 2-inch net pots. The holes should be drilled 6 inches from the sides of the foam and 12 inches apart.
Fill the garden container with water, one gallon at a time,until the water depth reaches 5 inches. Keep a record of how many gallons used.
Add a water-soluble fertilizer, such as 20-20-20 (nitrogen-phosphorus-potassium), to the water at a rate of 2 tbsp. per gallon of water.
Add Epsom salts to the water at a rate of 1 tsp. per gallon of water. Mix well to dissolve the fertilizer and Epsom salt into the water.
Place the net pots into the drilled holes of the plastic foam. Set the foam into the water solution.
Planting and Growing
Set one young mint plant into each net pot. Leave any topsoil attached to the roots in place.
Regularly top-up the nutrient solution in the hydroponic garden to a constant level of 5 inches in depth. Keep the water, fertilizer and Epsom salt ratios the same as previously indicated.
Harvest your mint leaves. Once a mint plant has a minimum of 5 to 6 mature pairs of leaves, you may begin harvesting the mint.