Cilantro, known scientifically as Coriandrum sativum, is a fragrant annual herb whose leaves are widely used in global cuisine, while its seeds are known as coriander. The question of growing this herb without soil is common, and the answer is yes, though the method you choose depends on your ultimate goal. You can certainly use water to start new plants or extend the life of store-bought sprigs. However, achieving continuous, robust harvests requires a more structured, nutrient-delivery system.
Distinguishing Propagation from Sustained Growth
It is helpful to understand the difference between simply rooting a cutting and truly growing a plant to maturity in water. Water propagation involves placing a stem cutting in water to encourage the development of new roots, typically for a short period before transplanting it into soil. This method uses water primarily for hydration and as a temporary medium to stimulate root growth.
In contrast, sustained growth in a water-based system, known as hydroponics, is a complete cultivation technique. A hydroponic setup is engineered to provide the plant with everything it needs for its entire life cycle, not just to sprout roots. Water alone provides the necessary hydration but lacks the macro and micronutrients required for the plant to produce a continuous supply of healthy foliage.
Simple Steps for Rooting Cilantro Cuttings
For quickly rooting cuttings or briefly extending the freshness of store-bought cilantro, a simple glass of water is sufficient. Begin by selecting healthy, non-wilted stems that are approximately 3 to 5 inches long. Use a clean, sharp implement to cut the stem just below a leaf node, as this is where new roots are most likely to form.
Remove all the lower leaves from the stem so that only the bare stem is submerged in the water, as any submerged foliage will quickly rot. Place the prepared cuttings in a clear container, such as a glass jar, ensuring only the bottom inch or two of the stem is covered. The container should be placed in a location that receives bright, indirect sunlight to prevent the water from heating up too quickly or the plant from scorching.
To prevent the buildup of bacteria and the depletion of dissolved oxygen, the water must be changed frequently. Replacing the water every one to two days is generally recommended to keep the environment clean and oxygenated.
Needs for Long-Term Water Cultivation
To achieve true, sustained growth and continuous harvesting of cilantro in a water-based system, a basic hydroponic setup is necessary. This method requires the introduction of external components to mimic the nutrient delivery and oxygen exchange that soil normally provides. The most pressing requirement is a balanced nutrient solution containing essential elements like nitrogen, phosphorus, and potassium (NPK), along with trace minerals.
Cilantro is a leafy herb and requires a nutrient mix that is relatively high in nitrogen to support strong foliage development. The electrical conductivity (EC), which measures the nutrient strength, should be maintained between 1.2 and 1.8 for optimal growth. Furthermore, the water’s pH level must be monitored and kept within a slightly acidic range of 5.5 to 6.7 to ensure the plant can properly absorb these nutrients.
The roots also require a constant supply of oxygen, which is not naturally abundant in standing water. Hydroponic systems address this through aeration, often by using an air stone and pump, or by circulating the water in a way that exposes the roots to air. Cilantro also needs 12 to 16 hours of steady, consistent light daily, which often necessitates the use of supplemental grow lights indoors. Maintaining a cooler temperature, ideally between 45 and 75°F, is also helpful to delay the plant’s natural tendency to “bolt,” or go to seed, which ends the leaf harvest.