Succulents are celebrated for their distinctive appearance and ability to withstand harsh, arid conditions. They thrive by storing water in their thick, fleshy leaves, stems, or roots, making them popular choices for indoor and outdoor growers. Despite their hardiness, many enthusiasts experience plant decline. Understanding the factors that cause this failure is the first step toward successful cultivation. This diagnostic guide identifies the most frequent causes of succulent decline.
The Dangers of Overwatering
Overwatering is the single most common cause of premature death for succulents because their physiology is designed for drought, not constant moisture. When the soil remains saturated for too long, the root system is deprived of oxygen. This lack of air causes the roots to die, inviting opportunistic fungal and bacterial pathogens, resulting in soft rot.
The visual signs of overwatering begin in the plant’s water-storing tissues. Leaves often appear mushy, soft, and swollen, sometimes becoming translucent or yellow as cells burst from excess water absorption. If overwatering continues, the rot travels up the stem, which may turn black or brown and feel squishy. Advanced rot can also emit a foul odor from the soil.
The misconception that succulents need frequent small sips of water is a common mistake. Instead, adopt a “soak and dry” method, allowing the soil to become completely dry between watering sessions. When watering, thoroughly soak the soil until water runs freely from the drainage hole, ensuring the entire root ball is saturated. This mimics the heavy but infrequent rainfall succulents experience.
Always check the soil moisture deeply before watering; inserting a wooden chopstick can act as a simple moisture indicator. If the stick comes out clean and dry, it is safe to water, but if it shows dampness, delay watering. Root death from rot can paradoxically cause the plant to display symptoms similar to underwatering, such as shriveling. This occurs because compromised roots can no longer absorb moisture. If your plant is shriveled but the soil is wet, the problem is root rot.
Diagnosing Light Deficiency or Excess
The correct balance of light is a precise requirement for succulent health, as issues arise from both too little and too much sun exposure. A lack of adequate light triggers etiolation, where the plant stretches excessively in search of a light source. This results in pale, weak, and elongated stems with widely spaced leaves, causing the plant to lose its compact shape.
The stretched growth of etiolation is permanent; the plant will not shrink back down, though new growth under proper light will be healthy. Succulents thrive in bright conditions, preferably with several hours of direct morning sun or bright, indirect light. Moving an etiolated plant to a brighter spot corrects future growth, but must be done carefully to avoid sunburn.
Sunburn occurs when a succulent unaccustomed to intense light is suddenly exposed to it, such as moving a plant from indoors to full outdoor sun. The damage appears as irreversible scorched patches on the leaves, which can be white, beige, brown, or black, and often have a rough, dry texture. Sunburn is cellular damage that reduces the leaf’s ability to photosynthesize.
To prevent scorching, plants should be slowly acclimated to brighter conditions over several weeks, a process called hardening off. Start with a few hours of morning sun and gradually increase the duration and intensity of the light exposure. Sunburn damage remains on the leaf until it is naturally shed, but new growth will be conditioned to the higher light levels.
Ineffective Soil and Container Choices
Drainage and Container Size
The physical environment of the pot is a factor in managing moisture and root health. A container must have a functional drainage hole at the bottom to allow excess water to escape immediately. Placing a plant in a decorative container without drainage, or leaving the pot sitting in a saucer of water, ensures the roots sit in stagnant moisture, promoting root rot. Using a container disproportionately large for the plant can also create problems, as the massive volume of soil takes too long to dry.
Choosing the Right Substrate
The substrate used for planting is equally important because standard potting soil retains moisture for leafy plants. Succulent soil must be highly porous and fast-draining, mimicking the gritty, rocky soil of their natural environment. Commercial cactus or succulent mixes are a good starting point, but they benefit from amendments to increase drainage further. Mixing cactus soil with inorganic grit like perlite, pumice, or coarse sand improves aeration and prevents compaction.
Identifying and Eliminating Common Pests
Mealybugs
Mealybugs are a common pest that appear as small, white, cottony masses often clustered in the crevices where leaves meet the stem or on new growth. These insects are sap-suckers, feeding on the plant’s vascular system, which results in stunted or deformed new leaves and general weakening.
To eliminate mealybugs, the most effective non-toxic treatment is 70% isopropyl alcohol applied directly using a cotton swab or spray bottle. The alcohol dissolves the protective waxy coating, killing the insect on contact without harming the plant, though a small area should be tested first. Isolate any infested plant immediately to prevent the pests from spreading to other succulents.
Fungus Gnats
Another frequent issue is the presence of Fungus Gnats, which are tiny, dark-colored flies that hover near the soil surface. The adults are mostly harmless, but their presence indicates the soil is staying damp for too long, as the larvae thrive in moist environments. The larvae feed on organic matter and occasionally chew on delicate succulent roots, compounding the damage caused by overly wet conditions.
Managing fungus gnats requires breaking their life cycle by allowing the top layer of soil to dry out completely between waterings. Yellow sticky traps placed near the soil surface capture the flying adults, helping to monitor and reduce the population. Additionally, sprinkling a layer of food-grade diatomaceous earth on the soil surface will physically desiccate and kill any emerging larvae or crawling adults.