Water chestnuts (Eleocharis dulcis) are aquatic plants native to China that were introduced in the U.S. in the 1930s. They produce long, green leaves that die back in the fall, when they develop edible fruits that are crunchy and slightly sweet. Water chestnut plants grow in soggy or marsh-like conditions, or in pots without drainage holes. Unfortunately, they will grow outside only in locations that have 220 frost-free days annually.
Fill large plant pots with a mixture of loam topsoil and clay, which is the optimal mixture for water chestnuts. Choose the deepest pots available, with a minimum depth of 12 inches and no drainage holes in the bottom. Fill the pots three-fourths full of the growing medium.
Apply a 2-inch layer of compost or manure to the mixture and work it into the soil well, using a hand spade. Allow the pots to sit for two to three weeks to allow the manure or compost to break down. Immediate planting can cause the water chestnuts to rot.
Dig a hole in the center of the pot that is a least 3 to 8 inches deep, depending the depth of the pot. Insert the water chestnut root into the hole with the pointed end facing up. Fill in the hole with soil.
Water the soil in the pot until it is soggy and at least 4 inches of water pools on top of it.