Edible soy bean plants, often referred to by their Japanese name of edamame, produce grean beans in pods that are similar to lima and other edible green bean seeds. The pods are inedible, but each one produces around three large beans. Plant soy beans in spring and choose a variety that has a short maturity period. Soy beans are day length sensitive and won't grow once the days are longer than 14 hours. Most seed catalogs and garden centers now sell several varieties of soy bean.
Prepare a well-draining garden bed that receives full sun. Lay a two-inch layer of mature compost over the bed and till it in to aid with drainage and soil nutrition.
Inoculate the soy beans seeds prior to planting if necessary. This ensures the plants are able to produce nitrogen as they grow. Inoculate is often sold with the seeds, or seeds are sold pre-inoculated. Fill a bowl with the inoculate powder and dip the slightly dampened seed in it to coat.
Water the bed until it's moist right before planting. Plant seeds six inches apart in a row. Sow the seed to a one-inch depth. Sow additional rows two feet apart from each other.
Water soy beans once weekly, providing approximately one inch of water per plant. Lay down a 2 to 3 inch layer of straw mulch to help preserve soil moisture and prevent weed growth.
Fertilize the soy beans with a nitrogen rich fertlizer six weeks after sowing. Apply the fertilizer to the soil six inches away from the base of the plants. Follow label instructions for exact application amounts.
Harvest the soy beans when the pods are still green and the beans inside are full and plump. Pick as the beans ripen.