Pea plants are a popular cool-season crop. Many cultivated varieties of the species Pisum sativum are vining plants that require support to grow upward. However, the growth pattern is not universal, as breeders have developed varieties with different habits. The plant’s ability to climb is rooted in specialized structures that allow it to anchor itself to supports. This adaptability means gardeners can select the pea type best suited for their space and cultivation method.
The Two Main Growth Habits
Pea plants are classified into two distinct growth habits: vining and bush. Vining peas, also called pole or climbing peas, have an indeterminate growth pattern, meaning they continue to grow and produce pods over an extended period. These varieties often grow between six and eight feet tall and require an external structure for support.
Bush peas have a determinate growth pattern, resulting in a more compact and self-supporting form. Dwarf varieties typically grow only two to three feet tall and produce their harvest in a concentrated burst. Popular types, such as shelling peas and snap peas, are available in both vining and bush forms. The choice depends on the gardener’s preference for height, space constraints, and desired harvest duration.
Understanding Pea Tendrils and Climbing Mechanism
The structure responsible for the vining pea’s climbing ability is the tendril, a thin, thread-like outgrowth that is a modified leaf or leaflet. These tendrils are constantly in motion, exhibiting a wide, circular growth movement known as circumnutation. This seeking motion increases the probability that the tendril will make contact with a suitable vertical support, triggering a response called thigmotropism.
Thigmotropism is a directional growth movement in response to touch. The side of the tendril touching the support slows its growth, while the opposite side accelerates, causing the tendril to rapidly coil and wrap around the structure. This coiling firmly anchors the vine, pulling the stem upward to reach for sunlight.
Growing Peas That Vine
Successfully cultivating vining peas requires a support system, as their natural growth pattern causes them to sprawl along the ground. Trellising, staking, or caging is necessary to manage the plant’s height and prevent the vines from becoming a tangled mass. Support structures should be at least six feet tall for most vining varieties to accommodate their mature height.
Appropriate materials include wire fencing, nylon netting, or sturdy A-frame trellises, which provide a lattice for the tendrils to grip. Installing this support when seedlings are small (around two to three inches tall) ensures the plant can begin climbing immediately without root damage.
Keeping the vines off the ground using a trellis improves air circulation, which reduces the risk of soil-borne diseases. This also makes harvesting the pods much easier.