The begonia is a popular seasonal plant, frequently grown in containers or garden beds, that thrives in warm, temperate conditions. Since most varieties are native to tropical and subtropical regions, they cannot survive freezing temperatures and must be brought inside for the winter in cold climates. Successfully overwintering a begonia depends entirely on its type, as the method will either involve maintaining active growth as a houseplant or inducing a period of dormancy in storage. Knowing the specific kind of begonia you possess is the first step toward preserving it for the following season.
Choosing the Overwintering Method
The decision to keep a begonia actively growing or to store it for dormancy hinges on whether the plant is fibrous-rooted or tuberous-rooted. Fibrous-rooted begonias, which include the common wax begonia (Begonia semperflorens) and cane-type varieties like Angel Wing begonias, lack an underground storage structure. These plants must be kept growing throughout the winter if they are to survive.
Tuberous begonias, recognized by their large, showy flowers, naturally enter a dormant period when temperatures drop and daylight hours shorten. These varieties form a thick, underground storage organ—the tuber—that allows them to survive the cold months. Keeping a tuberous begonia actively growing indoors is discouraged, as it often leads to weak, leggy growth and susceptibility to disease.
Rhizomatous begonias, often grown for their decorative foliage, are also fibrous-rooted but possess a thick stem that creeps along the soil surface. Like the cane and wax types, these begonias can be kept as houseplants, though they may experience some leaf loss as they adjust to lower light conditions.
Pre-Move Preparation and Pest Management
Before any begonia crosses the threshold into your home, preparation and sanitation are necessary to prevent an indoor pest infestation. Inspecting the plant is paramount, as outdoor pests like spider mites, aphids, and mealybugs can rapidly colonize the stable environment of a heated home. These pests are often hidden on the undersides of leaves or nestled in stem joints.
Pruning the begonia back by up to one-third removes leggy summer growth and decreases the amount of foliage that might harbor insects or fungal spores. Following the pruning, the plant should be treated with an appropriate insecticide, such as horticultural oil or insecticidal soap, paying careful attention to saturate the entire plant, including the soil surface. A quarantine period of two to three weeks in a separate area, away from existing houseplants, is recommended after treatment. This isolation allows you to monitor for any residual pests or the development of mildew before integrating the begonia into your main collection.
Indoor Care for Actively Growing Begonias
Fibrous-rooted and rhizomatous begonias require adjustment when maintained for active winter growth indoors. The greatest challenge indoors is providing sufficient light, as reduced winter sun limits the plant’s ability to photosynthesize effectively. Place the begonia in the brightest possible location, such as an east or south-facing window that provides bright, indirect light; direct afternoon sun can scorch the leaves. If natural light is inadequate, supplemental lighting using a fluorescent or LED grow light for 12 to 14 hours daily will prevent the plant from becoming excessively spindly.
Watering frequency must be substantially reduced. Allow the top inch or two of soil to dry out completely between waterings to prevent the development of root rot, a common issue for overwatered indoor plants. Fertilization should be entirely suspended or applied only at half-strength every four to six weeks, as the plant cannot utilize high levels of nutrients during this resting phase.
Begonias prefer average indoor temperatures between 65 and 75 degrees Fahrenheit. They are particularly susceptible to dry air, which is common in homes heated by forced air, so placing the container on a pebble tray filled with water can help raise the localized humidity level around the foliage. Cold drafts from windows or doors, as well as heat from nearby vents, can cause leaf drop and damage, so positioning the plant away from these temperature extremes is advisable.
Storing Tubers for Dormancy
Tuberous begonias must be allowed to enter their natural dormant cycle. Begin the process in early autumn by gradually reducing water and discontinuing fertilization to encourage the foliage to yellow and die back. After the first light frost naturally kills the top growth, or when the foliage has completely died back, the tubers can be carefully lifted from the soil.
Once lifted, remove most of the remaining soil and cut the stems down to about one to five inches above the tuber. The tubers should then be allowed to “cure” or dry out for one to two weeks in a cool, dry area away from direct sunlight. This curing process helps seal the tuber’s outer layer, minimizing the risk of fungal infection during storage.
After curing, gently brush off any remaining soil or roots, but avoid washing the tubers, as moisture encourages rot. Store the tubers in a container filled with a dry medium such as peat moss, vermiculite, or sawdust, ensuring the tubers are not touching one another. The ideal storage location should be dark, dry, and maintain a cool temperature range between 40 and 50 degrees Fahrenheit. Checking the stored tubers monthly for any signs of rot or shriveling allows for the removal of damaged pieces, ensuring the health of the remaining stock until they are ready to be replanted in the spring.