The common green bean (Phaseolus vulgaris) is one of the most widely cultivated vegetables globally. Whether this plant grows on vines does not have a single answer because the species exhibits significant diversity in its growth patterns. This difference is a result of genetic variations. This variability means some green bean varieties are vining plants, while others maintain a compact, self-supporting structure.
Understanding the Two Main Types
The Phaseolus vulgaris species is categorized into two primary groups based on growth habit: pole beans and bush beans. This difference is governed by whether the plant possesses a determinate or indeterminate growth pattern. Determinate types (bush beans) reach a specific size and then stop vegetative growth to focus on producing their crop. Indeterminate types (pole beans) continue to grow and produce foliage and flowers throughout the entire season until cold weather intervenes.
This distinction is rooted in the plant’s apical meristem, the growing point at the tip of the stem. In bush beans, the apical meristem develops into a reproductive flower bud, halting the vertical growth of the main stem. Conversely, the apical meristem in pole beans remains vegetative, continuing to produce new stem tissue and nodes indefinitely. This genetic difference explains the dramatically different physical structures of the two bean types.
The Vining Habit of Pole Beans
Pole beans exhibit a true vining habit, which is the ancestral form of the common bean plant. These plants display indeterminate growth, allowing their main stems to continually lengthen and seek support. They typically grow to heights between 6 and 15 feet, depending on the variety and growing conditions.
Pole beans climb using a twining habit, where the slender vines wrap around a support structure, such as a trellis, stake, or corn stalk. Because their growth is continuous, they require a sturdy external framework to prevent heavy foliage and crops from collapsing. This prolonged growth cycle results in a harvest spread out over a longer period, often yielding beans for six weeks or more.
The Compact Nature of Bush Beans
Bush beans represent the non-vining counterpart, characterized by a compact, upright structure. These varieties possess the determinate growth habit, meaning the plant stops growing vertically once it has reached its mature height. Bush bean plants rarely exceed 1 to 2 feet in height, forming dense, self-supporting mounds.
They do not require external support like trellises or poles because their stems are strong enough to hold up the plant and its developing pods. This growth pattern causes the plant to produce a large, concentrated flush of beans all at once. The harvest is typically ready within a narrow two-week window, which is beneficial for gardeners who wish to preserve a large quantity of beans.