Waterlily Growth Rate

Invasive Waterlilies

• Some types of waterlilies have such a fast growth rate that they are considered not a healthy addition to a pond environment, but are instead classified as an invasive weed. The yellow waterlily reproduces through both seeds and rhizomes under the water, and matures so quickly that it can completely cover the surface of a small pond in a matter of weeks. The higher the nutrient content in the water, the more quickly yellow waterlilies will grow, until they drain a large amount of the water's nutrient content. Also known as spatterdock, these water lilies not only grow incredibly quickly but also produce leaves that float on top of the water and leaves that are submerged, making it a fast process for the pond to be overtaken.

Noninvasive Waterlilies

• Waterlilies that are considered noninvasive have a much slower growth rate. The fragrant waterlily is one variety that is still capable of completely covering a large area such as a lake, but because it grows much more slowly than the yellow waterlily, it is more manageable. Even the reproduction process of the fragrant waterlily takes several days to complete, as the flowers only release certain seeds and pollens on certain days. However, as with the yellow waterlily, the speed at which the fragrant waterlily matures is highly dependent on the nutrients in the water. Typically, after dying off to the rhizomes during the winter months, the fragrant waterlily will grow leaves in the spring and be fully flowering by May.

Control Methods

• Controlling the growth rate of the waterlily --- whether an invasive or noninvasive species --- is important to the overall health of the pond. Planting other types of plants in the bottom of the pond will help keep the nutrient level down, as they, too, use what is available in the water. This can slow the growth rate of the most prolific waterlilies, and will also help to keep algae to a minimum. There are dyes available that are safe to use in a pond environment; these dyes will color the water and prevent light from reaching through the surface to the rhizomes, and will slow the growth rate. Pulling the waterlilies is typically only a temporary fix, as they reproduce prolifically.

Concerns

• Because waterlilies have such a fast growth rate, be absolutely sure you want to include them in a pond before actually introducing them; once they are established, they are difficult to get rid of. The shade created by the attractive leaves can prevent sun from reaching other plants and aquatic life, and the quickly growing plants can also remove much of the water's nutrient content.