The Life Cycle of Bean Plants

Seed

• Holding a small dried bean in the palm of your hand, it's hard to imagine that everything needed to grow a new bean plant--and its entire annual crop of new bean pods and seeds---is all right there. But so it is. Inside every bean seed is a dormant plant embryo and all the stored food energy necessary to support germination and the initial growth of the new plant's root and above-ground stem.

Germination

• Bean seeds are usually planted 1 to 2 inches deep in warm, rich soil. The seeds begin to germinate almost immediately once watered. Absorbing "wakens" it from dormancy, and the seed soon bursts through the hard protective seed coat. The embryo's tiny white root emerges first, growing downward to anchor the plant and begin to draw life-giving water and nutrients from the soil. The embryonic shoot or stem grows upward through the soil as it continues to unfold.

Seedling

• Emerging from the soil bent like a hairpin, its folded embryonic leaves the last to emerge, the new shoot is known as the hypocotyl. It quickly straightens and its two embryonic "leaves," known as cotyledons, open outward. The cotyledons store the last of the seed's food energy and continue to feed the plant as it "greens up" with chlorophyll, produces its first leaves and begins to photosynthesize, or produce its own food energy.

Flowering Plant

• The seedling stem shoots up and produces many more leaves, becoming a young adult then a mature plant. Pole beans continue to grow as a vine; bush-type beans develop a bush form with side branches. Within six to eight weeks, depending on the bean type and cultivar, the plant reaches reproductive age and begins to produce flower buds.

Pollination

• As bean flowers open, pollination occurs, beginning the process of sexual reproduction. Pollen from the male part of the flowers is deposited by gravity and wind drift onto the female flower parts, or ovaries. Insects may help the process along, but for the most part beans are self-pollinated. Each fertilized ovary begins to emerge as a very tiny bean pod, usually before flower petals have withered. Watering too much or too little and very hot weather may cause flower drop, which greatly diminishes bean production.

Bean

• The immature beans or pods develop very rapidly, and are typically very bright green in color. If beans are left on the plant to ripen fully, they will fill with developing seeds---individual bean seeds---that cause the pod to bulge. Once fully dried, the pod releases its mature seeds, which start the life cycle all over again if planted the following year.