Begonias are popular ornamental plants known for their impressive foliage and bright, continuous blooms, often used to add vibrant color to garden beds, containers, and hanging baskets. The United States Department of Agriculture (USDA) Hardiness Zone 6 represents a significant portion of the central and eastern US, where winter temperatures regularly drop below freezing. Gardeners frequently ask whether their begonias can survive the cold and return the following spring. This article clarifies the perennial status of the most common begonia varieties in Zone 6 and provides guidance on how to preserve them through the winter.
Defining Begonia Hardiness in Zone 6
Begonias are tropical and subtropical plants, native to warm, humid regions of Central and South America, Asia, and Africa. Because of their origin, garden begonias cannot tolerate the freezing temperatures of a Zone 6 winter. The USDA Hardiness Zone 6 is defined by an average annual minimum winter temperature range of -10°F to 0°F, a range that is lethal to most common begonia types.
The two most frequently grown varieties, Tuberous Begonias (Begonia x tuberhybrida) and Fibrous or Wax Begonias (Begonia semperflorens), are not true perennials in this climate. They are instead treated as tender perennials or annuals, meaning they must be replanted each spring if they are not brought indoors. Tuberous begonias are especially vulnerable; their tubers cannot survive a frozen ground and will rot if exposed to temperatures below 45°F for an extended period.
A notable exception is the species Begonia grandis, often called the Hardy Begonia, which is reliably perennial in Zone 6 and can tolerate temperatures down to -10°F. This variety survives by producing small bulbils that drop to the ground in the fall and sprout in the spring, allowing it to return year after year. However, garden begonias prized for their large flowers or bedding color will not survive unless protected from the cold.
Overwintering Techniques for Tuberous and Fibrous Begonias
Since most begonias will not survive a Zone 6 winter outdoors, gardeners must employ specific overwintering methods to preserve their plants. The technique used depends entirely on the begonia type and its growth habit.
Tuberous begonias require a period of dormancy to survive the winter. After the first light frost causes the foliage to die back, the tubers must be carefully dug up. The remaining stems should be cut down to a few inches above the tuber, and the plant material must be allowed to cure in a warm, dry location for several days.
Once the tubers are dry and excess soil is gently removed, they need to be stored in a cool, dark, and dry environment that remains above freezing, ideally between 45°F and 55°F. The tubers should be nestled in a medium like peat moss, vermiculite, or sawdust to prevent desiccation. Regularly checking the stored tubers is necessary to discard any showing signs of decay or rot.
Fibrous begonias, such as Wax Begonias and Cane Begonias, do not form tubers and are best saved by bringing the entire plant indoors. Before moving them inside, the plants should be inspected for pests and pruned back to a more manageable size. They should be repotted if necessary and treated as temporary houseplants throughout the winter months.
These indoor plants require bright, indirect light. Watering should be significantly reduced compared to the active growing season, though the soil should never be allowed to dry out completely. Maintaining slightly moist soil and avoiding fertilizer until spring ensures they remain healthy without attempting excessive growth during the low-light winter period.
Optimal Spring and Summer Care in Zone 6
Successful cultivation in Zone 6 focuses on maximizing the relatively short warm season and carefully timing the transition outdoors. Begonias should not be planted outside until all danger of frost has passed, which typically means waiting until late May or early June. The nighttime temperature should consistently remain at or above 50°F to prevent chilling injury and ensure active growth.
Tuberous begonias can be started indoors six to eight weeks before the last expected frost to get a head start. When planting, the tubers should be placed just below the soil surface with the concave side facing upward. All begonia types thrive in rich, well-draining soil high in organic matter.
Most begonias prefer a location that receives bright, indirect light or morning sun, as intense afternoon heat can scorch the leaves. Consistent, regular watering is required, especially in containers, but the soil must not become waterlogged to prevent root rot. Applying a balanced liquid fertilizer every few weeks from early summer through early fall will support vibrant foliage and flowers.