To answer this, we must first look to our origins. We, Haworthiopsis, are native to the arid, rocky landscapes of Southern Africa. In this harsh environment, the sun is intense and direct. To survive, we have evolved not as sun-worshippers like some cacti, but as masters of partial shade. We often grow nestled between rocks or under the scant cover of bushes, which provides us with bright but filtered light. Our succulent leaves are designed to store water, and our photosynthesis is a specialized process (Crassulacean Acid Metabolism or CAM) that allows us to open our stomata at night to minimize water loss. This efficiency means we do not require the constant, intense solar energy that other plants crave.
The term "low light" is relative. For a sun-loving plant like an Echeveria, a north-facing windowsill would be disastrously dim. For us, however, it is often quite tolerable, if not ideal. We interpret "low light" as an area that receives no direct sunlight but has strong, consistent ambient light for most of the day, such as a bright office under fluorescent lights or a room with a large north-facing window. This is our minimum threshold. True "low light"—such as a dark corner far from any window—is a challenge we are not equipped to handle for extended periods.
When placed in conditions we perceive as low light, our growth will change dramatically. Our most noticeable response is etiolation. This means our stem will begin to stretch unnaturally, reaching awkwardly towards any available light source. Our normally compact, tight rosette of leaves will become loose and elongated, with more space between each leaf. Our coloration will also fade; the beautiful stress-induced hues of red, purple, or deep green may wash out to a pale green or even yellowish tone as we produce less protective pigments. We will survive, but we will not thrive. Our growth will slow to a near halt, and our structural integrity will weaken, making us susceptible to physical damage.
A far greater risk in low light is not merely our awkward appearance, but the heightened danger of root rot. Our watering needs are intrinsically linked to light intensity. Light drives our metabolic processes and water usage. In bright light, we use the water stored in our leaves efficiently. In low light, our metabolism slows to a crawl, meaning we require water far less frequently. If our caretaker continues to water us on a schedule suited for brighter conditions, the water will sit in the soil, our roots will become oxygen-starved, and they will succumb to rot. This is a silent, underground killer that can claim us quickly.
While we can persist in low light, we sincerely prefer bright, indirect light for many hours a day. An east or west-facing window is often perfect, providing us with gentle direct sun for a short period. If your space only offers low light, please help us by watering us extremely sparingly. Allow the soil to become completely dry and then wait a further week or two before providing a thorough soak. This drastic reduction in watering is the single most important factor in keeping us alive under these stressful conditions. Furthermore, consider supplementing with a grow light; even a few hours a day can prevent etiolation and keep us healthy and compact, allowing us to display our true, beautiful form.
