From a botanical perspective, English Ivy (Hedera helix) possesses a key physiological trait that makes growing it in water alone a distinct possibility: the ability to readily produce adventitious roots. These are roots that form from non-root tissue, such as a stem or leaf node, often in response to environmental conditions like high humidity or submersion. When you place an ivy cutting in water, the nodes perceive the moisture and hormonal signals trigger the development of these water-adapted roots. These aquatic roots are structurally different from soil roots; they are often finer, less woody, and better at absorbing oxygen and nutrients directly from the water column. This inherent adaptability is the fundamental reason why propagating and temporarily sustaining English Ivy in water is a common and successful practice.
While an ivy cutting can survive and even show initial vigorous growth in pure water, this is primarily fueled by the energy reserves stored within its stem and leaves. For the plant to thrive long-term and undergo essential processes like photosynthesis, cell division, and the production of new vines and foliage, it requires a complete suite of macro and micronutrients. Pure water lacks these vital elements—most critically Nitrogen (N), Phosphorus (P), and Potassium (K), as well as trace elements like iron, magnesium, and calcium. A plant in water will eventually deplete its internal stores. The result will be a gradual decline manifested as stunted growth, smaller new leaves, chlorosis (yellowing of leaves due to lack of chlorophyll), and an overall weakened state that makes the plant susceptible to diseases. It is living, but not truly thriving.
A paramount concern for any plant living in water is root respiration. Roots need access to oxygen to perform cellular respiration and generate energy. In well-aerated soil, oxygen pockets exist between soil particles. In a static glass of water, oxygen can become depleted rapidly, leading to root rot—a condition caused by anaerobic bacteria and fungi that attack and decay the oxygen-starved root system. The plant will effectively drown. To mitigate this, the water must be changed frequently (at least once a week) to reintroduce dissolved oxygen. Using a container that allows for some air exchange around the roots (e.g., a narrow-necked vase) can also help support the submerged root system by maintaining a higher humidity zone around the base of the plant.
To transition from mere survival to actual growth in water, you must replicate the conditions of a hydroponic system. This means providing the plant with the nutrients it lacks. Simply switching from plain water to a diluted, balanced hydroponic nutrient solution can completely transform the plant's health and growth potential. A weak solution added to the water every time you change it (or as directed on the product) will supply the essential elements for photosynthesis and development. Furthermore, ensuring the plant receives adequate bright, indirect light is non-negotiable. Light provides the energy driver (ATP and NADPH from the light-dependent reactions) that powers the Calvin cycle where sugars are synthesized, a process entirely dependent on the nutrients now available in the water.
