Growing coriander (cilantro) in water is a simple form of hydroponic propagation that extends the life of store-bought herbs and maintains a continuous supply. This method involves rooting healthy stem cuttings directly in a water vessel, which provides a fast and clean way to grow the herb without soil. While propagating coriander from seed in water is possible, starting with established cuttings offers a significantly higher success rate and a much quicker path to harvest.
Essential Supplies and Preparing Cuttings
You will need a clean, clear glass jar or container to hold the cuttings, which allows you to monitor water clarity and root development. A sharp, sterile tool, such as scissors or a knife, is necessary to make clean cuts. While plain filtered water is sufficient initially, some growers choose to keep a highly diluted liquid fertilizer or rooting hormone on hand for later use, though it is not mandatory for root formation.
Selecting the right stems involves focusing on healthy, vigorous cuttings that are typically four to six inches long. Use the sterile tool to make a clean cut just below a leaf node, which is the point on the stem where a leaf or side shoot emerges and where rooting hormones are naturally concentrated. It is important to remove all leaves from the bottom two-thirds of the stem, as any foliage submerged in the water will quickly decompose. This decaying plant matter introduces bacteria to the water, creating an environment that promotes stem rot and inhibits healthy root growth.
Once the cuttings are prepared, place them into the clean vessel, adding fresh water so that only the trimmed stem ends are submerged by about one to two inches. Position the jar to receive light, ensuring the setup is ready for the ongoing care required to initiate root development.
Ongoing Care and Preventing Rot
Maintaining a healthy environment for your water-grown coriander relies heavily on light management and frequent water replacement. The plant thrives in bright, indirect light, such as a sunny windowsill that avoids the harsh, direct midday sun, which can overheat the water and stress the delicate cuttings. The ideal ambient temperature for growth ranges between 60°F and 75°F, as cooler conditions help to delay the plant’s natural tendency to “bolt,” or prematurely flower.
The most important maintenance task is changing the water completely every one to three days to prevent the growth of harmful anaerobic bacteria and algae. Regularly replacing the water also replenishes the dissolved oxygen supply, which is critical for the stems to initiate root growth and prevents the water from becoming stagnant. If you notice a slimy residue forming on the submerged stems or the container’s interior, this is a clear sign of bacterial buildup, requiring an immediate water change and a gentle rinse of the stems.
After the initial white, thread-like roots are established, you may introduce a tiny amount of liquid nutrient solution to the fresh water to support sustained leaf production. This hydroponic nutrient blend should be extremely diluted, often to a quarter of the strength recommended for soil-grown plants, because too much fertilizer will quickly burn the newly formed roots. To further prevent algae growth, consider transitioning the cuttings to an opaque container once roots are established, as this blocks light from reaching the water.
Harvesting Coriander Successfully
Once the cuttings have developed a robust root system and begun to produce a flush of new, healthy leaves, they are ready for harvest. This typically occurs when the new growth is several inches tall, indicating the plant has sufficient energy reserves to recover from clipping. The most effective method for harvesting is the “cut-and-come-again” technique, which sustains the plant for a longer yield.
Use a clean, sharp pair of scissors to snip the mature, outer leaves and stems, leaving the central cluster of young leaves, or the crown, completely intact. This practice encourages the plant to continue directing its energy toward producing new growth from the center. It is important to avoid harvesting more than one-third of the plant’s total foliage at any given time, which minimizes shock and ensures the plant can continue to photosynthesize effectively. When the stems become thick, woody, or the growth noticeably slows down, it signals that the plant has reached the end of its productive cycle in water. At this point, the best approach is to start a new batch by taking fresh cuttings to ensure a continuous supply of fresh coriander.