Once you've chosen the type and style of your garden pond, the next consideration is plants for it. Do visit a garden center in your area that specializes in or is knowledgeable about aquatic plants. They will be able to help you make the right plant choices for your locale. Maintaining a healthy garden pond which is clean and clear, with the correct balance between water plants and algae is essential. The water plants will compete with the algae for nutrients. These nutrients come from the fish droppings and nitrogen from the rotting plant material. Algae growth can be kept in check by shading at least half of the garden pond to prevent the sunlight from encouraging algae growth.
There are many types of plants available for use in a garden pool. Considerations such as water depth, amount of sunlight and how each species relates to its surroundings need to be taken into account when choosing plant material. Both floating leafed and submerged plants are needed for a healthy garden pond and should be included in your selection. Water garden plants are called aquatic plants, because their life cycle revolves around water. Aquatics plants come in different types such as: emergent or marginal plants; submerged or oxygenating plants; and floaters, the so-called ground covers in garden ponds and marsh plants. (Tip: Only introduce fish in your garden pond once the oxygenating plants are established because the fish will destroy them as well as the balance in the garden pond.)
Oxygenating plants, or submerged plants are important as they are responsible for the food, shelter, oxygen and spawning medium for fish. Oxygenating plants are also commonly known as pondweed. They are anchored with coarse gravel in mesh containers and will grow quickly and establish roots if left undisturbed. Because they are fast growers and rarely protrude above the surface, they will need thinning in smaller garden ponds. These aquatic plants are important in maintaining the quality of the water in garden ponds. They produce oxygen for use by both plants and fish. By utilizing nitrogen produced from decaying plant material and fish waste products, they deprive algae of nutrients. (Tip: It is best to cage these plants if the garden pond contains fish which tend to forage on submerged plant foliage.)
Nine to ten bunches of oxygenating plants per square meter (5.8 feet square) of pond surface will be sufficient to keep a garden pond healthy. Following are a few examples of oxygenating plants that can be used in garden ponds:
Emergent plants are sometimes also called marginals or marsh plants. These plants are grown along the edges of garden ponds where the roots are attached to the muddy bottom and portions of their stems are above the water. Some of them are even planted in water up to a depth of 20 cm (7.8 inches). It is very important to choose the right plants to suit the size of your particular garden pond. Roughly one-third of the pond margin should be covered with marginal plants to have a balanced effect. Emergent plants are usually placed so that the top of the pot is at or barely below the water level. Bog plants are also considered to be marginals. There are many different species of bog plants with varying heights, textures and foliage colors that add height and drama to water gardens. Following are a few examples of emergent plants that can be used in garden ponds:
Deep water plants occur further from the edge, between shallow and deep water, are other emergent plants where roots are attached to the bottom, but have floating leaves above the water. These plants usually have their leaves floating on the surface of the water and are essential in the maintenance of the correct balance in the garden pond. These plants shade the water and prevent the sun from reaching the algae; they also provide shelter for fish and other small animals. Above all they are very ornamental and dramatic. These plants like to be planted up in a heavy soil without any organic material. (Organic material would only encourage algae to grow.) It is a good idea to make use of special mesh containers to plant deep water plants in. You should cover the soil surface with coarse gravel or small stones to prevent the fish from removing the soil. A good balance can be achieved by planting one plant for every 2.5 square meters (26 feet square) of pond surface. Following are a few examples of deepwater plants that you can use in deep water gardens:
Though most are not grown for their flowers, some like lotus and water-lilies, are extremely dramatic and a feast for the eye when in flower. Bog plants are available for those not able to locate their garden pond in sufficient sunlight to support plant growth. Some bog plants can survive in locations that have as little as three hours of sun and still provide interest to water gardens.
Floaters are not rooted in the soil, but are allowed to float freely above or below the water surface. They are not as effective as the oxygenators but do not require anchorage. Floaters enhance the display of water lilies and lotus as well as adding a finishing touch to the water garden. They are the so-called ground covers of the garden pond world. They may be restricted by a framework to prevent them from moving around or allowed to float freely with the breeze. This produces an ever-changing look to the water surface. Some floaters are very prolific and may need to be kept in check by scooping out excess plants on occasion. If you do not keep it in check you will soon find that they become pestful like a weed.
Algae are another plant type that is found in most garden ponds. There are hundreds of species of algae that can grow in garden ponds. Generally algae attach itself to the sides of the garden pond and remain innocuous. Some species of algae, namely the dreaded 'blanket weed' can grow up to a foot a day under ideal conditions and can rapidly clog a garden pond. On the other hand free floating algae is microscopic and is what causes pond water to appear green.
Water gardens need a mix of aquatic plants to attain a balanced system. You need to ask yourself the following: What look do you want? Do you want colors and textures, tall or short, lily pads and flowers or a combination of all?