The question of whether beans grow in the ground or above it often stems from confusion with root crops. For widely consumed common beans (e.g., kidney, navy, or green beans), the plant uses the ground for its foundation while producing the harvestable product above the soil line. The seed is placed directly into the earth to germinate, but the entire reproductive part of the plant—the pod containing the beans—develops in the air and sunlight. This growth pattern is characteristic of legumes.
Clarifying the Growth Location
The soil’s primary function is to provide a stable anchor and a source of water and nutrients for the root system. Unlike root vegetables, the edible part of the bean plant, the seed-filled pod, develops on the aerial stems. This ensures the pods are exposed to air for pollination and sunlight for the energy needed to mature the seeds. Harvesting common beans never involves digging up the soil.
This growth habit applies to the vast majority of beans and peas in the Fabaceae family. A notable exception is the peanut (Arachis hypogaea), which uses a unique process called geocarpy. Peanut flowers are pollinated above ground, but the fertilized ovary elongates into a “peg.” This peg grows downward, pushing the developing pod into the soil where the peanut matures underground.
The Anatomy of a Bean Plant
A bean plant’s structure divides labor between its below-ground and above-ground components. Below the surface, the plant develops a deep taproot for stability and a network of lateral roots. These roots feature specialized nodules that host symbiotic bacteria, enabling nitrogen fixation by converting atmospheric nitrogen into a usable form.
The stem emerges from the soil, transporting water and nutrients absorbed by the roots up to the leaves and pods. The leaves use photosynthesis to convert sunlight into sugars, fueling the plant’s growth. Flowers, which develop into the pods, are positioned high above the soil to maximize light exposure and aid reproduction.
Two Main Ways Beans Grow
Bean plants are categorized into two distinct growth habits based on their above-ground stem structure: bush beans and pole beans.
Bush Beans
Bush bean varieties, such as ‘Blue Lake,’ are compact plants that grow to a maximum height of one to two feet. They are self-supporting and do not require stakes or trellises, making them a preferred choice for small-space gardeners. They tend to produce their entire crop almost simultaneously, often within a short two-week window.
Pole Beans
Pole beans are vining plants that can grow aggressively, reaching heights between six and fifteen feet. These plants require a vertical support system, such as a trellis or cage, to climb. While they take longer to begin producing pods than bush varieties, pole beans offer a higher cumulative yield and continue to produce beans over a much longer season.