The common houseplant Pothos, or Devil’s Ivy (Epipremnum aureum), is widely recognized for its resilience and adaptability. While its roots thrive in an aquatic environment, the plant’s foliage cannot survive long-term underwater. Pothos can successfully transition from a terrestrial existence to a hydroponic one, but only if the balance between submerged roots and aerial leaves is maintained.
How Pothos Thrives in Water
Pothos is uniquely suited for water culture because of its natural physiology as an aroid vine that produces aerial roots. These roots normally help the plant climb and absorb moisture from the air in its native tropical environment. When placed in a liquid medium, they readily convert to water roots. A cutting placed in water will sprout new roots from its nodes, which are the small bumps located along the stem, allowing the plant to sustain itself indefinitely without soil. This method is a form of passive hydroponics.
For long-term health, the water must be regularly refreshed to prevent stagnation and replenish the dissolved oxygen necessary for root respiration. A change every few weeks is generally sufficient to avoid anaerobic conditions that promote rot and bacterial growth. Since water contains no nutrients, the plant will eventually require a small amount of diluted liquid fertilizer to maintain growth. Pothos can survive on its stored energy for a significant period before needing nutrients.
Why Leaves Must Stay Above the Waterline
While the roots adapt well to water, the leaves and stems are not designed for full submersion and will quickly fail in an aquatic environment. Pothos leaves are equipped with stomata, microscopic pores primarily located on the underside, responsible for gas exchange. These stomata must have direct access to air to allow the plant to take in carbon dioxide for photosynthesis and release oxygen and water vapor.
Submerging the leaves effectively blocks these pores, halting the process of gas exchange. This lack of access to atmospheric air causes the foliage to suffocate, and the leaf tissue will begin to break down rapidly. The waterlogged tissue quickly becomes susceptible to rot and mold, as the plant cannot perform its primary function of generating energy. Pothos is fundamentally a terrestrial plant, and its leaves are structurally unsuited to withstand the lack of air beneath the waterline.
Practical Applications for Partial Submersion
The successful use of Pothos in a water-based system relies entirely on partial submersion, where only the roots are placed in the water. This method is often used in decorative vases or as a natural filter in aquariums. To set up a cutting, ensure that all foliage is removed from the section of the stem that will be submerged, leaving only the stem and nodes underwater. The leaves and the crown, where the stem meets the water surface, must remain dry and exposed to the air to ensure proper respiration.
In an aquarium environment, Pothos roots absorb nitrates and other compounds directly from the water, which naturally purifies the tank and maintains water quality. This technique utilizes the plant’s robust root system for filtration while respecting the biological limits of the foliage. The goal is to have a significant portion of the root mass submerged, allowing the plant to draw water and nutrients, while the vine and all its leaves trail outside the vessel.