From a botanical perspective, English Ivy (Hedera helix) can indeed be grown in water only, a method known as hydroponics. This plant possesses a high degree of adaptability. Its stems produce adventitious roots, which are roots that develop from non-root tissues, such as stem nodes, in response to specific environmental conditions like consistent moisture. When a cutting is placed in water, these pre-formed root primordia are stimulated to grow, allowing the plant to absorb water and, to a limited extent, draw upon the minimal nutrients dissolved in the water itself to sustain basic metabolic functions for a period.
While an ivy cutting can survive in plain water for many months, merely surviving is not the same as thriving. For sustained, healthy growth, plants require a complete suite of essential macro and micronutrients. Water alone, even tap water, lacks sufficient concentrations of key elements like nitrogen (N), phosphorus (P), and potassium (K), as well as critical minerals like iron, calcium, and magnesium. Initially, the cutting will rely on the energy stores within its own tissues. However, without an external nutrient source, the plant will eventually exhibit signs of severe deficiency. Growth will become stunted, new leaves will be small and pale (chlorotic), and the overall vitality of the plant will decline, making it susceptible to disease.
Several physiological challenges arise for a plant existing solely in water. First, oxygen availability to the root zone is limited. Soil structure contains air pockets that facilitate root respiration. In a stagnant water environment, roots can suffocate, leading to root rot. This is why it is crucial to change the water frequently to reintroduce dissolved oxygen. Second, algae growth is a common issue. Algae will compete with the ivy for the limited nutrients and oxygen in the water, further stressing the plant. It can also coat the roots, inhibiting their ability to function properly. Finally, without the structural support of a growing medium, the plant may become top-heavy and unstable as it grows larger.
For long-term cultivation, a water-only system is suboptimal for English Ivy. To make it a more viable permanent solution, the water must be augmented with a balanced hydroponic nutrient solution. This provides the necessary elements for photosynthesis, structural development, and overall health. The plant would also benefit from being placed in an opaque container to inhibit algae growth and having its water changed every one to two weeks. It is important to note that roots that develop in water (water roots) are anatomically different from those that develop in soil (soil roots). They are better adapted to absorb water in a low-oxygen environment but are more fragile. Therefore, if you wish to eventually transfer a water-grown ivy to soil, it should be done sooner rather than later, as the transition becomes more difficult for the plant to acclimate to as the root system matures.
