How to Grow a Japanese Long Bean

Remove unwanted vegetation from a garden area located in full sun with well-drained soil. Kill the grass or weeds with an herbicidal spray at least one week prior to planting. Pull the vegetation out using your hands or with a hard rake.

Test the soil’s pH level before planting the Japanese long beans. Use a soil testing kit, following directions, or test the soil at your local county cooperative extension office. The beans grow best in soil that is slightly acidic, with a pH level between 6 and 7, according to University of Minnesota Extension.

Amend alkaline soils to make them more acidic to promote healthy Japanese long bean plant growth. Spread 4 to 6 inches of compost or manure over the garden soil. Work the material down into the soil approximately 6 inches using a shovel. Level the planting area using a hard rake and water the soil.

Install a climbing support for the Japanese long beans before planting the seeds. Use an arbor, trellis, or install 6-foot poles at each end of the garden. Bury the support poles approximately 8 to 12 inches deep into the soil. Firm the area around the buried support poles by stepping on the ground around them. Wrap the poles top to bottom with twine, spanning the distance between the two poles.

Plant the Japanese long bean seeds approximately 3 inches in front of the support. Bury the beans according to package directions or approximately ½ inches deep. Cover the bean seeds with soil. Space the bean seeds 4 inches apart.

Water the Japanese long beans after planting. Saturate the garden soil with water. Water the beans daily to keep the soil moist. Sprouting occurs in approximately one week.

Fertilize the Japanese long beans monthly. Use a 24-0-15 or 30-0-10 blend, according to University of Minnesota Extension. Spread the fertilizer 4 to 6 inches away from the plant, keeping it off the foliage. Water the fertilizer into the soil and off the foliage after the application. Follow the label’s instructions concerning rates.

Harvest the Japanese long beans at any size and before the inner seeds become apparent in the pod. Snip the bean from the plant using hand pruners. Allowing the beans to become too mature results in tough, fibrous beans.