Succulents are plants biologically designed for survival in arid environments, storing water in their fleshy leaves and stems to endure long periods of drought. This specialized adaptation suggests they cannot live in static water forever. Confusion often arises because water is successfully, but temporarily, used as a medium for propagating new plants. While a cutting may develop roots in water, this temporary rooting process is fundamentally different from providing a permanent habitat for a mature plant.
How Succulent Biology Adapts to Arid Environments
Succulents have evolved adaptations that allow them to flourish in climates where water is scarce and temperatures are high. Their thick, fleshy leaves or stems serve as a natural reservoir where water is efficiently stored. This high storage capacity is paired with a low surface-to-volume ratio and a protective waxy cuticle layer, both minimizing water lost through evaporation.
Many succulents employ a specialized form of photosynthesis known as Crassulacean Acid Metabolism (CAM). This metabolic pathway allows the plant to keep its stomata, the tiny pores used for gas exchange, closed during hot, dry daytime hours. They open their stomata at night when temperatures are cooler and humidity is higher to take in carbon dioxide, drastically reducing water loss through transpiration. The absorbed carbon dioxide is then converted into organic acids and stored in large vacuoles until the sun rises. During the day, the stored acids are processed, releasing carbon dioxide internally for photosynthesis to occur while the stomata remain closed.
The Temporary Role of Water in Succulent Propagation
The practice of water propagation often leads people to believe that succulents can thrive permanently in a purely aquatic environment. Placing a calloused cutting or a leaf in water quickly stimulates the growth of new, fine roots. This method is highly effective for rapidly establishing a root system and is popular among growers.
However, the roots that develop in water are physiologically distinct from those that grow in soil. These “water roots” are thinner, more fragile, and adapted to absorb oxygen dissolved in the water, contrasting with the thicker, sturdier roots developed in a terrestrial substrate. They grow quickly because they do not need to expend energy searching for water or nutrients, which are immediately available.
The challenge arises when these water-adapted roots are left indefinitely in water or are transitioned to soil. Water roots are designed for a constantly saturated environment and struggle to adjust to the fluctuating moisture levels and higher oxygen content of a typical soil mix. For a cutting to become a long-term, healthy plant, it must be transplanted into a well-draining soil mix once the water roots are established, allowing the plant to develop the robust, soil-adapted roots necessary for anchoring and nutrient uptake. A safe duration for water rooting is typically until the roots are visible and about an inch long.
Why Roots Cannot Survive Long-Term in Static Water
The primary reason succulents fail to survive in static water long-term relates directly to the respiratory needs of their root systems. Terrestrial roots require access to oxygen to perform cellular respiration, converting stored energy into a usable form for growth. In soil, this oxygen is pulled from air pockets that exist between the soil particles.
When a plant is fully submerged in static water, the dissolved oxygen content rapidly depletes as the roots use it, and the lack of air pockets prevents replenishment. This creates an anaerobic, oxygen-deprived environment that suffocates the roots. Root cells begin to die, turning dark brown or black and becoming soft.
This dead or dying root tissue is the perfect breeding ground for anaerobic bacteria and fungi, a condition commonly known as root rot. While clean, frequently changed water can temporarily delay this process during propagation, a mature plant’s larger root mass and increased metabolic needs quickly overwhelm the limited oxygen supply in a static water setup. The plant’s survival mechanism against drought does not protect its soil-adapted root system from the consequences of prolonged, waterlogged, anaerobic conditions.