Once again, the tremendous spring colors of aquatic plants are starting to bloom. It is that time of year again when water garden hobbyists get crazy excited. And with all of the varieties to choose from, its easy to see why. From the ever-popular water lily to the accented shoreline bog plants, buds are "springing up" everywhere.
Understanding the Nitrogen Cycle
To fully appreciate the value of how aquatic plants play a major role in pond balance, one should become familiar with the “nitrogen cycle”. A basic explanation of the cycle is shown below:
The nitrogen cycle begins with broken down fish waste or any organic matter which turns into harmful ammonia. Beneficial bacteria breaks down the ammonia into nitrites. Then, further along the cycle, the nitrites are broken down into harmless nitrates which are taken up by the aquatic plants. This is why it is easy to see the importance of controlled plant life in a pond.
Types of Aquatic Plants
There are four basic classes of aquatic plants with many variations within each class. The diagram below shows where they best grow in a pond.
Floating-leaved aquatic plants have roots that are attached to the bottom of the body of water in which they grow, but their leaves float on the waters’ surface. They are characterized by broad leaves, and examples of floating-leaved plants include water lilies and lotus. Below are examples of the much admired lilies, both the hardy type & tropicals.
|Hardy Lily||Red Lily||Pink Lily||Various Tropicals||Purple Tropical|
Emergent plants grow in water, but part of the plant remains above the waters surface. This adaptation allows the leaves to photosynthesize more efficiently, providing more oxygen and nutrients to submerged parts of the plant. In most cases, the leaves, flowers, and other reproductive parts float above the surface to enable pollination by insects and wind. There are numerous species of emergent aquatic plants, including water iris, cannas, or pickerels. Lotus and lilies can also be considered an emergent plant.
Submerged aquatic plants grow entirely underwater. They can either have roots that are attached to the bottom of the body of water in which they grow or have no root system at all. Some submerged plants remain attached to other aquatic plants. Examples of submerged plants are the anacharis, cabomba, and the sword plant. Submerged plants are also called oxygenators because they actually filter the pond water.
Free-floating plants remain suspended on the waters surface. They have broad leaves and stems that attach to neighboring plants to create a dense net of free-floating plants. Free-floating aquatic plants are not attached to the bottom of the body of water in which they grow, and are therefore easily moved by wind and waves. Examples of free-floating aquatic plants include the water lettuce and water poppies.
|Water Lettuce||Water Poppies|
Controlling Aquatic Pond Plants
As mention above, when explaining the Nitrogen Cycle, controlling the growth of plant life in a pond plays an important role. If allowed to grow unchecked, aquatic plants can be a detraction from the beauty of other features in a pond. This is especially true for koi ponds where the “stars of the show” are the colorful koi. Although it is true that with an abundance of plant life, the water usually remains very clear, the basic purpose of a koi or garden pond is to benefit an area aesthetically. When planting a pond, the idea is to step back and view it as a whole project. Also, after planting, keeping them trimmed and well maintained brings the entire project into proper balance and perspective.
As an example, shoreline plants such as papyrus, water iris or canna “frame” the edges of a pond. While floating leaved plants such as lilies or lotus, with their brilliant colored flowers, are the plant life center of attention in a pond. Floating leaved plants also help provide added shade and protection from predators for koi.
Plants in Pots
Koi will often eat lily plants or even dig up the bottom roots. When potting lilies, place ¾” smooth river rock to discourage uprooting the root ball. If koi are eating the leaves, they made need more food or need to be fed more often.