How Weather Affects Bean Plants

Temperature

• Beans are warm-weather crops -- and should not be planted until the soil temperature reaches 50 degrees F, as they may simply rot rather than germinate at cooler temperatures, according to the Purdue University Cooperative Extension. Most gardening experts recommend waiting until the soil temperature is between 60 and 70 degrees F before planting beans, which may be well after the average last frost date. Different types of beans benefit from different temperature conditions through the growing season, so select beans that best reflect the summer weather of your region. Lima beans, garbanzo beans and southern cowpeas require a long, warm growing season, while fava beans prefer a long, cool season and will not thrive in dry summer heat. Bush snap beans and wax beans mature quickly and are more tolerant of diverse temperatures and short growing seasons.

Rain

• Bean plants need about an inch of water each week to ensure proper flower formation and bean-pod development. Too little rain may be cured by watering, but too much rain can result in poor production and deformed pods. Rain can also contribute to the development of fungi. Thinning bean plants sufficiently to allow air circulation and planting in mounds or raised beds to encourage drainage in wet areas can help offset the damaging effects of too much rain. Don't harvest beans or weed in your bean patch when the leaves are wet to avoid spreading disease from plant to plant, advises Mother Earth News. Although beans require very little fertilization, excess rains can wash nutrients out of the soil, especially water-soluble minerals like calcium. Replenish the soil with regular doses of seaweed-based fertilizers or a top dressing of compost during rainy seasons.

Wind

• Bean plants are brittle and can be easily damaged by intense winds. Pole beans get heavy with beans and full-summer foliage, and strong wind can push over the whole teepee or trellis of beans. Anchor pole-bean supports well by inserting them deeply into the ground and bracing trellises with diagonal support bars or guy lines. Keep bush and pole beans well picked to encourage additional bean-pod growth and to lighten the plant to better resist wind damage. Ironically, some wind damage may actually benefit older bean plants, according to Steve Solomon at Northwest Garden News. Removing withering leaves from mature plants that are losing steam in their production cycle encourages new growth and a new round of pod production. For best effect, plant beans in a place protected from wind and remove selected leaves at the end of the season yourself rather than risk random wind damage.

Humidity

• Soup-bean varieties are left growing on the plant until the pods are thoroughly brown and dry in late fall. Rain or high humidity in the late-summer to early-fall drying period can cause fungal and bacterial growth on the bean pods, rendering them unusable or unfit for long-term storage. If a wet autumn is predicted, pull up the whole soup-bean plant, shake extra dirt off its roots and bring it inside to a dry location, such as a garage or attic. Hang the plants upside down from a string or rafters until the bean pods are brittle. Shell or thresh the beans to remove the dried pods, and store the dry beans in air-tight containers until cooking.