Begonia Temperature Tolerance: What Are the Limits?
Explore the full temperature spectrum for healthy begonias, from their ideal comfort zone to the upper and lower limits that cause stress.
The begonia genus is a diverse group of plants, appreciated for their striking foliage and colorful flowers. Native to subtropical and tropical regions, these plants have specific environmental preferences. Providing the correct temperature is a primary factor in helping them flourish, whether they are grown indoors as houseplants or outdoors in garden beds and containers.
Ideal Temperature Range for Begonias
Most common begonias, including popular wax and rex types, thrive in temperatures that are also comfortable for people. The ideal daytime temperature range is between 65 and 75 degrees Fahrenheit (18-24°C). At night, a slight drop in temperature is not only tolerated but can be beneficial, with a preferred range of 60 to 70 degrees Fahrenheit (15-21°C).
Maintaining temperatures within this optimal window encourages vigorous development, supports the production of vibrant leaves, and promotes consistent flowering. While some specific varieties, like cane-stemmed begonias, have a slightly narrower preferred range of 58-72°F (15-22°C), the general comfort zone for most household varieties remains consistent. This stability allows the plant to function efficiently without stress from extreme heat or cold.
Begonia Cold Tolerance and Winter Care
Begonias are not frost-tolerant, and temperatures dropping below 50°F (10°C) can cause significant harm. When exposed to cold, the plant’s cells can freeze and rupture, leading to visible signs of damage. Indicators of cold stress include wilting, the browning or blackening of leaves, and stems that become soft and mushy.
Care strategies for cold weather depend on the type of begonia. For common annual or wax begonias planted in garden beds, they are often treated as annuals and discarded after the first frost. However, potted wax begonias can be brought indoors before temperatures fall into the 40s F and kept in a location with bright, indirect light to survive the winter.
Tuberous begonias can be preserved by encouraging them to go dormant. To do this, gradually reduce watering in late summer and, after the first light frost has yellowed the foliage, dig up the tubers. Cut the stems back, allow the tubers to dry for several days out of direct sun, brush off the excess soil, and store them in a cool, dark, dry place between 40-50°F, often packed in peat moss or sawdust.
Begonia Heat Tolerance and Summer Care
Most begonias will show signs of heat stress when temperatures consistently rise above 85°F (29°C). Symptoms of heat stress include wilting leaves, flower drop, and leaf scorch, which appears as crispy, brown edges on the foliage. In prolonged heat, the plant’s overall health will decline, and it may cease blooming altogether.
Protecting begonias during summer heatwaves is centered on managing their light exposure and moisture levels. Moving potted plants to a location that receives shade during the hottest part of the afternoon is an effective strategy. Plants in garden beds benefit from being situated where they are shielded from intense, direct sun.
Ensuring the soil remains consistently moist helps the plant manage heat. Water the plants at their base when the top inch of soil feels dry, which may be more frequent during hot spells. Good air circulation is also beneficial, as stagnant, hot air can create an environment ripe for disease.