The genus Begonia is one of the most diverse groups of flowering plants, containing over 2,000 species discovered in tropical and subtropical regions. This immense variety means begonias exhibit a wide range of growth habits, from tiny groundcovers to large, shrub-like specimens. This diversity often leads to the question of whether any of these plants are capable of true climbing, similar to ivy or grapevines. This article clarifies the growth mechanisms of begonias and explains why some varieties appear to defy the natural tendency of the majority of the species.
The Definitive Answer: Begonia Growth Habits
The vast majority of begonia species and cultivars are classified into three main groups based on their underground structures: fibrous-rooted, tuberous, and rhizomatous. Fibrous-rooted begonias, such as the common wax begonia, maintain an upright or mounding shape. Tuberous varieties grow from a solid storage organ and are often upright or cascading. Rhizomatous begonias, like the popular Rex varieties, spread horizontally just below or on the soil surface, resulting in a low, spreading habit.
Crucially, begonias lack the specialized biological structures that define a true climbing vine. They do not produce tendrils, which are thin filaments that coil around supports, nor do they possess suckers or twining stems for vertical ascent. The stems of most begonias are too succulent and fragile to support their own weight if they were to grow vertically without assistance.
While the majority do not climb, a few rare species in the wild, such as Begonia glabra, are documented as true root-climbers. These exceptions use small, adventitious roots that emerge from the stem to cling to rough surfaces like tree bark or rock faces. These root-climbing species are not commonly found in garden centers or grown as houseplants. The perception of climbing typically arises from varieties that are simply very tall or have long, lax stems that trail.
Begonia Varieties That Scramble or Trail
The begonia varieties most often mistaken for climbers are the Cane Begonias, which include the popular Angel Wing types like Begonia maculata. These plants earn their name from their thick, segmented stems, which resemble bamboo canes and grow rigidly upright. In ideal conditions, these canes can reach impressive heights, sometimes exceeding five feet, giving the false impression of a self-climbing plant.
This vertical growth is achieved by scrambling or leaning, not by clinging. The stems are inherently strong but become top-heavy as the plant matures and produces large leaves and flower clusters. Without external support, the stems will eventually lean or flop over due to their own weight, especially when exposed to wind or rain. The appearance of “climbing” is merely the plant scrambling through or leaning against neighboring plants or structures for stability.
Trailing or Scandent Begonias, often grown in hanging baskets, also contribute to the confusion surrounding vertical growth. These varieties, which include many pendulous tuberous begonias and fibrous-rooted types like Dragon Wing, develop long, limp stems that naturally cascade downward. While primarily trailers, their stems can be trained to grow horizontally or slightly upward if gently secured to a support, giving them a scrambling appearance. This growth habit, characterized by flexibility, is a common adaptation for plants growing on slopes or in dense tropical undergrowth.
Providing Support and Training for Vertical Growth
For tall, scrambling Cane Begonias, external support is necessary to maintain an upright form and prevent the brittle canes from snapping. Gardeners must proactively install supports like bamboo stakes, metal hoops, or small trellises when the plant is young. This allows the plant to grow straight and develop a stronger structure before the weight of the foliage and flowers becomes too much.
The canes must be secured to the support using soft materials like garden twine, plant clips, or strips of fabric. It is important to tie the stem loosely, creating a loop that allows for future stem expansion without causing constriction or damage. Tying too tightly can restrict sap flow and create an entry point for pathogens, which can be detrimental to the plant’s health.
Pruning is another technique used to manage height and encourage a more robust, vertical habit. Pinching off the growing tips of young canes forces the plant to divert energy to side shoots, resulting in a fuller, bushier plant with less tendency to become leggy. Older, overly tall canes can be cut back to just above a node, which stimulates new, stronger growth from lower on the stem or from the base of the plant.