The common houseplant, Pothos (Epipremnum aureum), is widely recognized for its ease of propagation, quickly establishing roots in water. Its robust rooting ability has led to a popular claim among plant enthusiasts: that Pothos cuttings can accelerate the rooting process of other, more difficult-to-propagate species. This practice suggests that the Pothos plant releases a beneficial substance into the water that acts as a natural rooting aid for nearby cuttings. This article explores the biological mechanism behind this idea, the practical methods used by hobbyists, and how this natural approach compares to commercially available rooting products.
The Biological Mechanism: Auxin Production in Pothos
The theory behind using Pothos centers on the production of auxins, a specific class of plant hormones. Auxins are signaling molecules that govern many aspects of plant growth and development, including the initiation of new roots, known as adventitious root formation. Pothos is a vigorous, fast-growing vine that naturally produces high levels of the auxin Indole-3-acetic acid (IAA).
When a Pothos stem is cut and placed in water, the plant responds to the injury by increasing IAA production at the wound site to stimulate repair and new root growth. This hormone acts by encouraging cell division and differentiation, effectively instructing certain plant cells to become root cells. The concentration of these hormones at the cutting site is what allows Pothos to root reliably and quickly.
The practice assumes that concentrated IAA, or other beneficial compounds, will leach out of the Pothos stem and into the surrounding water. Once dissolved, these molecules are theoretically available for neighboring plant cuttings to absorb through their cut tissues. This low concentration of natural auxin would then provide the necessary hormonal signal to jumpstart the rooting process in the adjacent cutting.
However, the scientific community often regards the amount of auxin leached into the water as biologically negligible. IAA is highly diluted in the water medium and is also photosensitive, meaning it degrades quickly when exposed to light. The concentration dissolved in the propagation water may not be high enough to have a measurable, consistent impact on another plant’s root development. Therefore, the effectiveness of the leached concentration is a subject of debate.
Practical Application: Using Pothos Water to Aid Other Cuttings
Hobbyists utilize the Pothos plant’s rooting properties through two primary methods: co-propagation and water harvesting. The co-propagation method is the simplest, involving placing one or more Pothos cuttings directly into the same vessel as the target cuttings. This allows the Pothos to release its rooting compounds directly into the shared water supply as it develops its own roots.
The ideal Pothos cutting for co-propagation should be a healthy stem segment containing at least one node, which is the point on the stem where the leaves and aerial roots emerge. Placing multiple Pothos cuttings with a single difficult-to-root cutting is thought to increase the concentration of released compounds, maximizing the potential benefit. This method is often preferred for plants that are moderately easy to root, such as Philodendrons or certain herbaceous species.
The second method, water harvesting, involves creating “Pothos tea” by allowing Pothos cuttings to root in a container of water for several weeks first. During this period, the water is believed to become enriched with released hormones and other exudates. The Pothos cuttings are then removed, and the target cuttings are placed into this pre-conditioned water.
A practical tip for both methods is to avoid changing the water completely, instead opting to simply top it off as it evaporates. This strategy aims to maintain the concentration of any beneficial chemicals that have accumulated in the vessel. The process is best suited for soft or semi-hardwood cuttings, which are more responsive to external hormone application than mature, woody stems.
Efficacy Compared to Synthetic Rooting Hormones
The Pothos method provides a natural, low-dose application of IAA, which contrasts sharply with commercial rooting products. Synthetic rooting hormones, available as powders, gels, or liquids, contain concentrated doses of manufactured auxins like Indole-3-butyric acid (IBA) or Naphthaleneacetic acid (NAA). These synthetic compounds are structurally similar to natural IAA but are more stable and potent, designed to deliver a precise, high-impact hormonal signal.
Commercial products provide a predictable and robust stimulus, leading to a higher rate of success with cuttings, especially for species that are challenging to propagate. The concentration in these synthetic products is meticulously controlled, ensuring maximum efficacy when applied directly to the cut end of a stem. For large-scale propagation or species requiring a significant hormonal push, commercial rooting products remain the industry standard.
The Pothos method offers an unregulated and significantly lower dose of natural auxin. While it is a cost-effective and organic approach, its effectiveness is often inconsistent due to the unknown, variable concentration of leached hormones and their rapid degradation. The Pothos technique is best viewed as a supplemental aid for casual home propagation or for cuttings already inclined to root easily in water. For difficult species, the precision and potency of synthetic rooting hormones are more reliable.