Begonias are diverse ornamental plants popular for their vibrant flowers and striking foliage. Whether they return each year depends entirely on their specific type and the local climate. Native to tropical and subtropical regions, begonias are not naturally adapted to survive freezing temperatures. For gardeners in most temperate regions, begonias are treated as tender perennials that require intervention to survive the cold season. Expecting a begonia to return automatically is only realistic in the warmest growing zones.
Categorizing Begonia Types
Begonias are broadly categorized into three main types based on their root structure, which dictates their growth habit and seasonal behavior.
Tuberous begonias grow from a thick, underground storage organ called a tuber. These varieties, prized for their large, showy flowers, are programmed to enter a dormant state. The foliage dies back in the fall, allowing the tuber to rest before sprouting new growth in the spring.
Fibrous-rooted begonias (wax begonias or Semperflorens types) develop a standard network of fine roots. These plants are typically grown as low-maintenance annuals that produce continuous, smaller flowers. Cane-type begonias, such as ‘Dragon Wing’ and ‘Angel Wing,’ are also fibrous-rooted.
Rhizomatous begonias feature thick, creeping stems called rhizomes that grow horizontally along or just beneath the soil surface. This group is grown primarily for its spectacular, patterned foliage, such as Rex begonia varieties. Unlike the tuberous type, these begonias do not possess a natural dormancy period and will attempt to grow year-round if conditions allow.
Climate and Begonia Survival
Begonias are sensitive to cold, particularly freezing temperatures, due to their tropical origins. Most common garden begonias are classified as tender perennials; they are capable of living for more than two years but lack the hardiness to withstand frost. Most species cannot tolerate temperatures below 50 to 60 degrees Fahrenheit.
Growers in the warmest regions (USDA Hardiness Zones 9 to 11) can leave most begonia types in the ground, where they reliably return each year. In these frost-free climates, the plants behave as true perennials, often growing continuously through the mild winter months. Outside of these zones, any begonia left unprotected will be killed by the first hard frost, forcing gardeners to treat them as annuals.
A few exceptions exist, such as the hardy begonia (Begonia grandis), which can survive outdoors year-round in zones as cold as 6 or 7. This species achieves perennial status by dying back completely to the ground in the fall and then re-emerging from its underground structures in the spring. For most other begonia varieties, survival in cooler climates depends on providing a warm, sheltered environment during winter.
Practical Steps for Overwintering
Overwintering begonias successfully requires different strategies depending on the plant’s root type to accommodate its natural growth cycle. Tuberous begonias are managed by inducing complete dormancy, while fibrous and rhizomatous types are kept actively growing indoors.
Overwintering Tuberous Begonias
Saving tuberous begonias begins when the foliage yellows or after the first light frost kills the above-ground growth. After the plant dies back, carefully dig up the tubers, avoiding damage to the fleshy storage organ. Cut the stems back to one or two inches above the tuber and gently brush off any loose soil.
The tubers must be cured for one to two weeks in a dry, cool area out of direct sunlight to allow the cuts to heal. Once cured, pack the tubers in a container filled with a dry, insulating material. Store the container in a cool, dark, and frost-free location, maintaining a temperature range of 40 to 50 degrees Fahrenheit, until the spring planting season.
Overwintering Fibrous and Potted Begonias
Fibrous-rooted, cane, and rhizomatous begonias, which do not go dormant, must be brought indoors before nighttime temperatures drop below 50 degrees Fahrenheit. Before the transition, thoroughly inspect the plants for pests or disease to prevent infestations from spreading inside. Acclimate the plants by moving them to a shadier outdoor spot for a week before bringing them inside.
Once indoors, situate these begonias near a bright window to receive ample indirect light, necessary to sustain growth through the short winter days. Since indoor heating can cause the air to become very dry, increasing humidity is helpful. Water the plants only when the top inch of soil feels dry, as overwatering during periods of low light can easily lead to root rot.