Kalanchoe is a popular flowering succulent prized for its thick, vibrant green leaves and clusters of bright, long-lasting blooms. Because it stores water in its fleshy foliage, many owners wonder if it requires the intense, direct sun often associated with desert plants. Understanding the difference between intense light and the plant’s true preference is essential for successful growth and repeat flowering.
The Optimal Light Spectrum
Kalanchoe thrives in bright, indirect light, not the harsh, unfiltered light of a desert environment. The plant needs a high quantity of light energy, but it must be diffused or filtered to prevent damage. Ideally, Kalanchoe should receive six to eight hours of light exposure daily to support vigorous growth and blooming.
If grown indoors, a south- or west-facing window is best, provided the intense midday sun is filtered through a sheer curtain or glass. Outdoors, Kalanchoe thrives best with morning light and afternoon shade. While it can tolerate a few hours of direct sun, powerful summer rays can easily overwhelm the plant.
Recognizing Light Stress
Improper light exposure quickly manifests as visible signs of stress, indicating either too much or too little light. Excessive, intense sunlight causes scorching or sun scald. This damage appears as brown or crispy edges on the leaves, or sometimes a reddish-brown discoloration as the plant attempts to protect its chlorophyll.
Conversely, insufficient light causes etiolation, where the plant elongates its stems in an attempt to reach a brighter source. Etiolation results in pale, weak, and spindly stems with widely spaced leaves. A lack of adequate light also hinders the plant’s ability to initiate flowering, resulting in a non-blooming plant.
Watering and Soil Requirements
Managing moisture is a foundational element of Kalanchoe care, as the plant is highly sensitive to overwatering. Use the “soak and dry” method: water thoroughly until it drains from the bottom, then allow the soil to dry out completely before the next application. Frequent, shallow watering is detrimental and leads to root rot because the thick leaves and stems store water. Watering frequency must be significantly reduced during the cooler winter months to accommodate the plant’s slower metabolism.
The soil medium must facilitate quick drainage. A commercial cactus or succulent potting mix is ideal, as it is loose, sandy, and gritty. For a custom mix, combine standard potting soil with amendments like perlite or coarse sand to increase aeration. The container must also have functional drainage holes, as pooling water suffocates the roots.
Temperature and Seasonal Adjustments
Kalanchoe thrives within a standard indoor temperature range, preferring daytime temperatures between 60°F and 85°F. Consistent exposure below 50°F can damage the plant, and freezing temperatures cause irreversible harm to the succulent tissues. Outdoor plants must be moved inside before the first threat of frost in the autumn.
As a photoperiodic or “short-day” plant, Kalanchoe’s flowering is regulated by the length of uninterrupted darkness it receives. To initiate a new bloom cycle, the plant requires approximately six weeks with 14 hours of total darkness each night. This biological trigger causes the plant to naturally flower in the winter when daylight hours are shortest.