Morning glories are flowering plants belonging to the family Convolvulaceae. They are known for their trumpet-shaped blooms that typically unfurl in the morning light and close by the afternoon. While cultivated as tender annuals in most temperate climates, they can behave as short-lived perennials in frost-free regions. The short answer to whether they climb is yes, as they are vigorous, fast-growing vines that can ascend a structure up to 10 feet in a single season.
The Mechanics of Twining
Morning glories achieve their rapid upward growth through a specialized method known as twining, where the entire stem revolves around a vertical support. The growing tip of the vine performs a circular search motion called circumnutation until it makes contact with an upright object. This movement is an energy-efficient strategy that allows the plant to reach for sunlight without needing to develop thick, self-supporting stems.
Once a suitable support is detected, the stem is stimulated by touch, triggering a response to curl around the object. The vine then pursues its vertical climb by forming a spiral that exerts pressure and tension on the support. Unlike other climbers, morning glories do not possess tendrils, suction cups, or aerial roots; they rely entirely on the main stem wrapping to secure their position. The direction in which the vine twines is genetically fixed for each species, typically spiraling in a counter-clockwise motion.
Providing Optimal Support Structures
The climbing mechanism of twining makes the physical dimensions of the support structure a primary factor in successful growth. Morning glories prefer supports with a relatively small diameter that their stems can easily coil around to maintain a grip. Supports should ideally be no more than 1.5 inches (4 cm) in diameter for the vine to twine effectively.
Structures that work well include trellises, arbors, and pergolas that have thin slats, wires, or cross-pieces spaced about 1 to 2 inches apart. For thicker structures like wooden fences or walls, gardeners can install taut vertical elements such as strings, wires, or plastic mesh netting for the vines to climb. It is important to ensure the support is secured firmly, as a mature vine laden with foliage can become heavy, especially when wet.
Managing and Training Growth
While morning glories are natural climbers, guidance ensures they cover the intended area and do not sprawl on the ground. When young seedlings emerge, gently guide the new growth toward the chosen support structure. If a vine begins growing horizontally or away from the support, you can loosely wrap the stem around the vertical element to encourage the correct twining behavior.
The vigorous growth habit means maintenance is necessary to keep the plant contained. Regular pruning helps control runaway vines and prevents them from smothering nearby plants or structures. Removing spent flowers, a process called deadheading, prevents seed pods from forming, which limits self-seeding and encourages the production of new blooms.