Rooting hormone is a tool used in plant propagation to help cuttings develop new roots. The active ingredients are synthetic versions of naturally occurring plant hormones called auxins. These auxins function as chemical signals to stimulate cell division and differentiation at the base of the cutting. Applying this product significantly increases the success rate and speed of growing new plants. Understanding how long the hormone remains effective, both in the container and after application, is key to successful propagation.
Active Ingredients and Formulation
Rooting hormones rely primarily on two synthetic auxins: Indole-3-butyric acid (IBA) and Naphthaleneacetic acid (NAA). These compounds mimic the plant’s own internal growth regulators, prompting the undifferentiated cells at the cutting’s base to form root primordia. IBA is the most common active ingredient, often favored for its effectiveness across a wide range of plant species.
These active ingredients are delivered in distinct formats, which influences their stability. Powdered formulations often use an inert material like talc as a carrier for the auxin. Liquid concentrates are typically dissolved in alcohol or water. Gels suspend the hormone in a viscous base that coats the cutting.
Product Shelf Life and Storage Conditions
The longevity of rooting hormone varies significantly depending on its formulation and storage. While synthetic auxins are relatively stable, the products degrade when exposed to environmental factors. Powders generally possess the longest shelf life, often remaining potent for three to four years when kept sealed and stored properly.
Liquid and gel formulations tend to have a shorter lifespan, typically lasting one to two years once opened. This reduced stability occurs because the base is more susceptible to contamination and chemical breakdown. Exposure to moisture is also detrimental to powdered hormone, causing the active ingredients to break down and clump.
Heat and direct light accelerate the degradation of the auxin molecules in all rooting hormone types. To maximize the product’s shelf life, it should be stored in a cool, dark, and dry location. Following these storage guidelines ensures the hormone remains at its advertised concentration and delivers the necessary chemical signal to the cuttings.
Duration of Hormone Action on Cuttings
Once rooting hormone is applied, its function is not to provide a continuous, long-term supply of chemicals. Instead, it acts as a concentrated initial signal. The active ingredients, IBA and NAA, are absorbed quickly by the plant tissue, often within hours of application. This rapid absorption triggers the necessary changes in cell metabolism required for new root formation.
The hormone’s primary job is complete once it has successfully induced the initial cell division at the base of the cutting. This initial signal causes cells to differentiate and form root primordia, which is the foundational step for adventitious root development. Since synthetic auxins like IBA and NAA are more resistant to enzymatic breakdown within plant tissues than natural auxins, their signaling effect is strong and persistent enough to initiate this process.
The subsequent growth of roots, which takes weeks or months, is driven by the plant’s own internal biology, stored energy reserves, and the surrounding environmental conditions. The external hormone does not need to remain active on the cutting for the entire rooting period. Therefore, the duration of the hormone’s action is measured in the short time it takes to deliver the chemical message and initiate the physiological changes, not the entire time it takes for the roots to fully emerge.