Kalanchoe is a popular succulent cherished for its vibrant, long-lasting blooms and relatively easy care. These plants display clusters of small flowers in shades of red, pink, orange, yellow, and white, emerging above thick, scallop-edged leaves. Understanding the environmental needs of Kalanchoe is important for its successful growth, especially concerning its tolerance to cold temperatures, which is often defined by plant hardiness zones.
Understanding Hardiness Zones
Plant hardiness zones provide gardeners with a guide to determine which perennial plants are most likely to survive winter temperatures in a specific location. The USDA Plant Hardiness Zone Map, widely used in the United States, divides North America into zones based on the average annual extreme minimum winter temperature.
Each hardiness zone represents a 10-degree Fahrenheit temperature range, with lower numbers indicating colder climates. Zones are further divided into ‘a’ and ‘b’ subsections, each representing a 5-degree Fahrenheit increment. While the map is a useful tool for perennial plants, it does not account for other factors like soil quality, rainfall, or summer temperatures.
Kalanchoe Hardiness Zones
Kalanchoe, a succulent native to tropical regions, is generally considered winter hardy in USDA Zones 9 through 11 or 10 through 12. In these warmer zones, Kalanchoe can typically thrive outdoors as a perennial, returning year after year. Temperatures below 50-55°F can cause the plant to suffer, and freezing temperatures (32°F) can be fatal.
For outdoor cultivation within these zones, Kalanchoe benefits from well-draining, sandy, or loamy soil to prevent root rot. It also requires ample sunlight, ideally full sun to partial shade or bright indirect light, with protection from intense afternoon sun. While Kalanchoe can tolerate some light frosts in zones 9-11, its foliage may die back.
Growing Kalanchoe Outside Its Zone
Gardeners in climates colder than USDA Zone 9 can still enjoy Kalanchoe by implementing specific strategies. One common method involves growing Kalanchoe in containers, allowing for easy relocation. Plants can be moved outdoors during warmer months when nighttime temperatures are consistently above 55-65°F and brought indoors before cold weather or when temperatures dip below 50-55°F.
When transitioning Kalanchoe indoors for winter, select a spot with bright, indirect light, such as a south or west-facing window. Maintain indoor temperatures between 59-85°F, avoiding drafts. Another approach for colder zones is to treat Kalanchoe as a seasonal annual, enjoying its blooms throughout warmer seasons and then replacing the plant once cold temperatures arrive.