Why Do Lima Bean Pods Fall Off Before They Are Ripe?

Causes of Pod Drop

• The fundamental cause behind pod drop in lima beans is stress, although the source of the stress may vary. Both thermal and moisture stress take a serious toll on the plants, causing them to abandon seed production to conserve energy. Excess heat, dry soil or very wet soil are all common causes of pod drop. Although it is impossible to reverse pod drop once it occurs, it is largely preventable in most cases if the proper cultural practices are used.

Hydrate the Roots

• Proper moisture is the key to successfully growing lima beans, particularly after they set pods. Too much moisture in the soil will damage the plant and cause pod drop, as will too little. An inch of water weekly during the summer months is adequate, although they may benefit from additional water during periods of extreme heat or drought. The soil should always be allowed to dry out in the top 1/2-inch between waterings to prevent disease. However, if the leaves begin to wilt and the soil feels dry, water deeply to rehydrate the foliage.

Shield the Soil

• Mulch is one of the most valuable tools for growing lima beans and preventing pod drop. It shields the soil, conserving moisture and regulating the soil temperature while keeping weeds at bay. Apply a 2- to 3-inch-thick layer of mulch around the base of the lima bean plant to encourage pod retention and healthy growth. An organic, biodegradable mulch such as pine straw, compost or shredded bark is best, although black plastic covers may also be used to similar effect.

Regulate Temperatures

• Lima beans originated in the tropics, so they require moderately warm temperatures during the summer months to successfully set pods. However, excess heat may cause the pods to drop. Regulating the temperature within the bed is necessary, both to encourage a large yield and to preserve the yield once it sets. During periods of extremely hot, dry weather, cover the lima bean plants with a row cover made of 2-percent shade cloth. Shield the plants from drying winds by placing a trellis barrier or potted plants along the side of the bed facing the direction of the wind, and keep the plants well-watered to help them cope when temperatures rise.