Kalanchoe, a flowering succulent native to Madagascar, is commonly sold as Kalanchoe blossfeldiana. These popular houseplants offer a vibrant splash of color, often throughout the winter months. Kalanchoe has specific light requirements tied to its desert origins. Understanding the balance of light and darkness is key to successfully growing this plant and encouraging it to rebloom year after year.
Optimal Light Conditions
For Kalanchoe to thrive indoors, it requires a significant amount of light. The ideal condition is bright, indirect sunlight, which provides the necessary energy for photosynthesis without scorching the plant’s leaves. These plants generally need a minimum of six to eight hours of bright light exposure each day to maintain a compact, healthy shape and support future flowering.
When positioning a Kalanchoe inside, an east-facing window is often the most favorable location. This exposure provides the plant with gentle, direct morning sunlight, followed by bright, indirect light for the rest of the day. A south-facing window can also work well, provided the plant is slightly offset from the glass or shielded by a sheer curtain to diffuse the light.
The intense midday or afternoon sun, especially from a west-facing window, poses a risk of leaf damage when magnified through a glass pane. Direct, harsh light can quickly dehydrate the plant and stress its foliage. The goal is to maximize light intensity while preventing the heat and focused energy that causes physical harm to the plant tissue.
Signs of Improper Light Exposure
The appearance of a Kalanchoe plant serves as a clear indicator of whether its light environment is appropriate. Insufficient light, a common issue indoors, causes the plant to stretch out, a process known as etiolation. Stems become weak and elongated, resulting in a leggy appearance with widely spaced leaves that are often paler green than normal.
Insufficient light leads to a reduction or complete absence of flower buds and blooms. If the plant is receiving light that is too weak, it will focus its limited energy on vertical growth rather than flower development. Moving a leggy Kalanchoe to a brighter location can halt further stretching, though the existing elongated growth will not revert.
Conversely, exposure to overly harsh, unfiltered light can also cause visible damage to the foliage. The most common sign of light overexposure is leaf scorch, which appears as brown or white, crispy patches on the leaves. This damage destroys the plant tissue.
In some cases, the leaves may turn a stressed shade of red or yellow, which is the plant’s mechanism for producing protective pigments to shield itself from excessive ultraviolet radiation. If these symptoms appear, the plant should be relocated immediately to a spot with more diffused light. This adjustment will prevent further damage and allow the Kalanchoe to recover its healthy green color over time.
Triggering New Blooms
Kalanchoe is a short-day plant, meaning its flowering cycle is triggered by the continuous, uninterrupted duration of darkness it receives. This is the key factor in coaxing a Kalanchoe to rebloom after its initial flowers fade. Replicating the long nights of its natural winter environment is necessary to initiate bud formation.
To prompt new blooms, the plant must be subjected to a strict schedule of extended darkness for approximately six to eight weeks. During this period, the Kalanchoe needs 12 to 14 hours of darkness every night. Even a brief exposure to artificial light can interrupt the process and reset the flowering cycle.
A common method is to move the plant into a dark closet or cover it with an opaque box or bag between the hours of 6 PM and 8 AM daily. For the remaining 10 to 12 hours, the plant must be returned to its bright, indirect light location to continue photosynthesis. Once small flower buds are visible, the restricted light treatment can be stopped, and the plant can resume its normal, bright light routine.