The genus Begonia encompasses a vast and diverse group of ornamental plants prized globally for their vibrant flowers and dramatically patterned foliage. With more than 2,000 species and countless hybrids, these plants originate primarily from tropical and subtropical regions. Their widespread popularity stems from their ability to thrive in shady areas and provide continuous color from spring until the first frost. Gardeners frequently use begonias in containers, hanging baskets, and as bedding plants.
Understanding Plant Life Cycle Classifications
Plant lifecycles are categorized into specific classifications that determine how long a plant is expected to live and grow. An annual plant completes its entire reproductive cycle within a single growing season, typically germinating, flowering, setting seed, and dying within one year. These plants must be replanted every spring to ensure their presence in the garden each season. Perennial plants, in contrast, live for more than two years, often returning to bloom year after year from their established root systems.
A third classification is the tender perennial, a plant that is genetically perennial but lacks the cold-hardiness to survive freezing temperatures. While they maintain a long-term life cycle in their native tropical or subtropical habitats, they cannot withstand the winter conditions of colder climates. In regions that experience frost, the tender perennial is functionally treated as an annual because it cannot survive the winter season outdoors.
The True Classification of Begonias
Begonias are botanically classified as tender perennials. In tropical zones that are consistently frost-free (USDA Hardiness Zones 10 and 11), begonias function as true perennials, surviving and growing year after year. Their delicate tissues cannot tolerate temperatures near or below freezing. Gardeners in temperate Zones 2 through 9 can expect the plants to die back completely when cold weather arrives unless they intervene.
The plant’s root structure further influences how it is categorized and how it survives the winter. Tuberous begonias are grown from a specialized, disc-shaped underground storage organ called a tuber, which allows them to enter a period of dormancy. Fibrous-rooted begonias, such as the common wax begonia, have a fine, thread-like root system and do not possess a storage organ to survive a cold dormancy. Rhizomatous begonias grow from thick, creeping stems called rhizomes that store water and nutrients.
Overwintering Begonias for Year-Round Survival
Gardeners in colder regions can successfully maintain their begonias for multiple years by implementing specific overwintering strategies. For tuberous begonias, the goal is to induce and protect a natural dormancy period. After the first light frost causes the foliage to yellow and die back, the tubers must be carefully lifted from the soil. The stems should be trimmed back to a few inches, and the tubers must be allowed to cure in a warm, airy location for one to two weeks to harden the outer skin.
Once cured, the excess soil is brushed away, and the tubers can be dusted with a powdered fungicide to prevent rot during storage. They are then packed in a dry, insulating medium such as peat moss, sawdust, or vermiculite. Store them in a dark, cool, and frost-free location where the temperature remains between 40 and 50 degrees Fahrenheit.
Fibrous-rooted begonias, including wax and cane types, cannot be stored as tubers and must be brought indoors before the first frost, preferably when night temperatures consistently drop below 45°F. The entire plant can be potted and treated as a houseplant for the winter season. Before moving them inside, inspect the foliage and treat any existing pests to prevent them from infesting indoor plants. They thrive best near a bright window that provides ample indirect light, and they should be kept consistently moist while avoiding overly wet soil and cold drafts. An alternative method is to take stem cuttings in the fall and root them over winter, discarding the original parent plant.