Succulents are plants highly adapted to thrive in arid environments, possessing specialized tissues for long-term water storage. This evolutionary design means they are exceptionally sensitive to consistently wet conditions, which can lead to significant health problems. The immediate answer is that prolonged full submersion is generally harmful and should be strictly avoided. Leaving a succulent submerged mimics a flood condition that its physiology is not equipped to handle.
The Immediate Danger of Prolonged Submersion
Keeping a succulent fully submerged, or allowing its roots to sit in constantly saturated soil, directly threatens the plant’s survival through root asphyxiation. Plant roots require oxygen for aerobic respiration to generate energy for nutrient and water absorption. When the air pockets in the soil are displaced by water for an extended period, the roots are deprived of this necessary oxygen supply.
This lack of oxygen creates anaerobic conditions, effectively suffocating the root system. Roots that die from asphyxia can no longer absorb water or nutrients, causing the plant to show symptoms of dehydration even though the roots are sitting in water. Furthermore, constantly wet, airless soil promotes the rapid growth of anaerobic fungi and bacteria, which then decay the compromised roots in a condition known as root rot.
In a succulent, this process can occur quickly because its tissues are already engorged with water, making it less tolerant of excess moisture. Once root rot takes hold, it can spread quickly up into the stem, turning the plant’s structure mushy and often proving fatal if not addressed immediately.
Understanding Succulent Water Storage and Physiology
Succulents are susceptible to overwatering due to their unique biological and evolutionary adaptations to desert and semi-arid climates. They possess thickened, fleshy parts—typically leaves or stems—designed to retain water for long periods. These specialized water-storing tissues, known as hydrenchyma, allow them to survive extended drought conditions.
A significant number of succulents also utilize a unique photosynthetic pathway called Crassulacean Acid Metabolism (CAM). Unlike most plants, CAM plants keep their stomata closed during the hot, dry daylight hours to minimize water loss from transpiration. They open their stomata at night when temperatures are cooler to collect and store carbon dioxide as malic acid.
This stored acid is converted back to carbon dioxide for photosynthesis during the day. This highly efficient water-saving mechanism means succulents are built to live on minimal, infrequent water sources, not constant moisture. Their physiology is optimized for storage and conservation, meaning they lack the mechanisms to cope with excess water.
Distinguishing Submersion from Recommended Watering Techniques
The confusion about submerging succulents often arises from beneficial watering methods that involve temporary water exposure. The most recommended technique for succulents is bottom watering, often described as a deep soak. This method involves placing the pot into a shallow container of water, allowing the soil to wick moisture upward through the drainage holes until the entire soil mass is saturated.
The goal of bottom watering is a thorough saturation of the soil, which encourages deep and robust root growth. This is fundamentally different from harmful submersion because the plant is only left in the water for a short, defined period, typically between 15 to 45 minutes. Once the top layer of soil feels moist, the pot must be removed immediately and allowed to drain completely.
Another technique sometimes confused with submersion is water therapy, a highly specific, temporary treatment. This involves removing a severely dehydrated or rootless succulent cutting and submerging only the bottom of the plant or roots in water for a brief period, usually 24 to 72 hours. Water therapy is not a regular watering routine for established, potted plants.
The golden rule for succulent hydration is to water deeply and thoroughly until water runs out of the drainage holes, and then allow the soil to dry out completely before watering again. The difference between proper care and fatal submersion is the immediate and complete drainage that prevents prolonged root contact with saturated soil.