How Bean Plants Need Light & Water

Planting Season

• Beans require adequate sun and warmth from the start; they germinate poorly without it. Plant bean seeds or seedlings after the frost lifts in spring, when nighttime temperatures reach 65 degrees F and soil temperatures reach at least 50 degrees F. Beans have relatively quick maturity times and do well with repeated plantings into the heat of midsummer.

Sun, Warmth and Space

• Beans thrive and produce their best harvests with six to eight hours of bright sun exposure every day. Blooming and fruit production fail in shady or cool conditions. Plant beans in sites with full sun, quick drainage and good air circulation. Give beans 2 to 6 inches in the row and 18 to 36 inches between plants to allow full air movement. Use trellis systems to tie pole beans up for best sun exposure.

Soil and Moisture Retention

• Bean plants have shallow root systems and require good moisture content in their soil. Till the top 10 inches of natural soil and add 4 inches of rich organic compost at planting. Compost adds nutrients for growth and holds moisture between waterings to support the bean plants. Amending the soil also warms the foundation for planting.

Watering and Mulch

• Purdue University's Department of Horticulture notes that beans need adequate moisture for growth, blooming and pod set, and recommends at least 1 inch of water per week. Extreme moisture fluctuations in the form of drought or over-watering lead to damaged harvests. Water bean plants in the morning to allow them to dry before nightfall, and use 2 to 3 inches of organic mulch on the soil to keep the foundation moist and warm.