Begonias are a popular choice for adding color to gardens and containers, but their outdoor duration depends entirely on the local climate and the specific variety planted. These tropical and subtropical plants are typically grown for their continuous blooms from planting until the first frost. While many gardeners treat them as seasonal annuals, most begonias are technically tender perennials whose survival is dictated by temperature rather than a natural life cycle. Understanding how long begonias last outside requires identifying the begonia type and knowing the expected local autumn temperatures.
How Begonia Type Determines Outdoor Duration
The majority of begonias sold for summer gardens fall into two main categories: fibrous-rooted and tuberous. Fibrous-rooted begonias, commonly known as Wax Begonias (Begonia semperflorens), have fine roots and are prized for their waxy foliage and continuous, small flowers. Tuberous begonias (Begonia x tuberhybrida) grow from a fleshy, underground storage organ and are known for their large, showy blooms. Both types are naturally perennial only in very warm climates, typically USDA Hardiness Zones 9 through 11, where ground freezing does not occur. In cooler regions, their outdoor life is limited to a single growing season, lasting from late spring planting until the first autumn frost.
The notable exception is the Hardy Begonia, Begonia grandis, which can survive winter outdoors in much colder regions. This specific species is a true perennial that tolerates temperatures down to USDA Zone 6, often returning year after year. The Hardy Begonia forms small, bulb-like tubers called bulbils and dies back completely in the fall. Its root system persists beneath the ground until spring, making B. grandis the only reliable choice for multiple seasons in the ground.
The Hard Stop: When Cold Temperatures Kill Begonias
For the common tender varieties, the outdoor season ends abruptly when temperatures drop low enough to cause cellular damage. Begonias experience cold stress when temperatures fall below 50°F, slowing metabolic processes and compromising cell membranes. This chilling injury can stunt growth and cause necrotic spots on leaves, but the plant may not die immediately. The true “hard stop” occurs at the freezing point of water, 32°F, which is fatal for nearly all tender begonias.
A single exposure to frost causes the water within the plant’s cells to freeze, forming sharp ice crystals that pierce and shred the cell walls. This irreversible damage manifests visibly as blackened, mushy, and translucent foliage and stems, a condition often referred to as frost damage. Because this cellular destruction is swift, begonias must be brought indoors or harvested before the first expected frost of the season. Even a brief, light frost is enough to destroy the plant’s structure beyond repair.
Bringing Begonias Indoors for Winter Survival
Since most begonias are technically tender perennials, it is possible to extend their life beyond a single outdoor season by bringing them indoors before cold weather arrives. The method for overwintering depends on the begonia’s root structure. Tuberous begonias are managed by inducing a period of winter dormancy, which mimics their natural cycle.
To prepare a tuberous begonia, the foliage should be allowed to die back naturally after the first light frost, or cut back before a hard frost hits. The tubers are then carefully dug up, and any loose soil is gently removed. They must be cured in a dry, cool area for up to two weeks to allow the outer layers to dry and harden. Once cured, the tubers should be stored in a dark, dry location, such as a cool basement or garage, kept above 45°F. They should be packed in materials like vermiculite, peat moss, or sawdust to prevent desiccation.
Fibrous-rooted varieties, like Wax Begonias, are generally treated as temporary houseplants rather than being forced into dormancy. Before overnight temperatures approach 45°F, the entire potted plant can be moved indoors after checking thoroughly for pests. They should be placed in a location that receives bright, indirect light and kept away from cold drafts or direct heat vents. Alternatively, gardeners can take stem cuttings in late summer to propagate new, smaller plants to keep indoors over winter. These indoor survivors can then be moved back outside the following spring after all danger of frost has passed.