The common houseplant Pothos (Epipremnum aureum) is highly adaptable, allowing it to thrive in various indoor environments. Pothos can grow in water indefinitely, not just for a short period of rooting. This ability makes it a favorite for simple, soil-free cultivation, provided specific physiological needs are met for long-term health.
Differentiating Rooting from Complete Submergence
Growing Pothos in water involves two distinctly different methods, only one of which is sustainable. The most successful approach is a hydroponic setup where only the stem nodes and roots are submerged, leaving the foliage entirely above the waterline. This method allows the plant to absorb water and nutrients through its specialized aquatic roots while the leaves are free to perform gas exchange in the air.
The second method involves the complete submersion of the entire plant, including the leaves, such as in a fully planted aquarium. Pothos leaves are not structured for life underwater and will rapidly decay due to their inability to access atmospheric carbon dioxide and oxygen. The rotting foliage can foul the water, making full submersion unsuitable for long-term survival. For a healthy, permanent water display, only the roots should be in the liquid medium.
Setting Up a Successful Water-Based Pothos System
To establish a thriving hydroponic Pothos, begin by taking stem cuttings that include at least three to four nodes. These nodes are the small bumps from which new roots will emerge. Place the cuttings in a container filled with water, ensuring all leaves are situated above the rim to prevent rot. Tap water is generally acceptable, but if the supply is heavily chlorinated, let the water sit in an open container for 24 hours so the chlorine can dissipate.
Choosing an opaque container over a clear one helps, as blocking light from the submerged roots significantly reduces algae growth. While the water level should be maintained by topping it up frequently, a full water change is recommended every few weeks to a month. This periodic replacement prevents the buildup of stagnant water and replenishes the limited dissolved oxygen supply available to the roots.
Physiological Adaptations and Growth Limitations
Pothos is part of the aroid family, which naturally favors the formation of adventitious roots, allowing it to transition easily from soil to water. The roots that develop in water are physiologically distinct from soil roots; they are thinner and lack the root hairs that help absorb nutrients in a denser medium. These roots are adapted to pull dissolved oxygen directly from the surrounding water, a process less efficient than soil aeration.
Growth in plain water is limited because water lacks the necessary macro and micronutrients found in soil. While Pothos can survive for months on stored nutrients or trace minerals in tap water, its growth rate will be significantly slower and the leaves smaller. For the plant to grow robustly and maintain vibrant color, it requires the addition of a diluted liquid fertilizer designed for hydroponics or houseplants. Consistent nutrient supplementation is necessary to prevent deficiencies like pale or yellowing leaves.