Wax begonias, known scientifically as Begonia semperflorens, are popular for their glossy leaves and continuous blooms, making them a favorite for both indoor and outdoor plant collections. These versatile plants are often used in bedding, borders, and containers, bringing vibrant color to various settings. Understanding their specific temperature needs is important for ensuring their health, vigorous growth, and abundant flowering throughout the year.
Optimal Temperature Range
Wax begonias thrive in warm conditions, with an optimal temperature range that supports their robust growth and prolific blooming. For indoor cultivation, a consistent temperature between 65°F and 75°F (18°C to 24°C) is ideal. This range promotes healthy development and encourages continuous flower production.
While they are adaptable, wax begonias generally prefer temperatures between 60°F and 75°F (15°C to 24°C) for optimal performance. Consistently being outside this preferred range can result in stunted growth or reduced flowering.
Protecting From Cold
Wax begonias are sensitive to cold and are not frost-tolerant, meaning freezing temperatures can cause significant damage. Temperatures falling below 50°F (10°C) can begin to stress the plants, leading to visible signs of distress. Common indicators of cold stress include wilting leaves, discoloration such as yellowing or browning, and even leaf drop as the plant tries to conserve energy. Severe cold damage can cause parts of the plant to die back entirely.
To protect outdoor wax begonias from cold, bringing potted plants indoors is an effective measure before temperatures consistently drop below 50°F (10°C). For plants in the ground, temporary protection can be offered by using frost cloths or blankets during unexpected cold snaps. Ensuring plants are moved away from cold drafts, especially near windows and doors, is also beneficial for indoor specimens. If a plant has suffered cold damage, trimming away affected leaves can help encourage new growth and recovery.
Managing High Temperatures
High temperatures can also impose stress on wax begonias, impacting their health and ornamental appeal. Temperatures consistently above 85°F (29°C) can lead to symptoms such as wilting, leaf discoloration, and even leaf burn. In extreme heat, plants may shed leaves or experience stunted growth as they struggle to cope with the environmental conditions. Prolonged exposure to intense heat can reduce flowering and may even cause flower buds to drop before opening.
Mitigating heat stress involves providing adequate shade, especially during the hottest parts of the day. For potted plants, relocating them to a shadier spot, such as under a tree or on a covered porch, can offer immediate relief. For plants in the ground, a shade cloth can effectively reduce direct sunlight intensity. Proper watering, especially in the morning or evening, helps keep the soil moist and can aid in cooling the roots, further supporting the plant through hot spells.
Seasonal Temperature Care
Wax begonias are typically grown as annuals in cooler climates but can be tender perennials in USDA zones 9-11, where winters are mild. In regions with colder winters, plants grown outdoors need to be brought inside before the first frost to ensure their survival. This transition should occur when nighttime temperatures begin to consistently fall below 60°F (15°C).
When moving plants indoors for the winter, it is beneficial to acclimate them gradually by placing them in a shadier outdoor spot for a few days before bringing them fully inside. While indoors, watering should be reduced as growth slows, but the soil should remain slightly moist. Once warmer temperatures return in spring, typically after all danger of frost has passed and night temperatures consistently stay above 50°F (10°C), plants can be moved back outdoors.