Aquatic Plant Selection
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 pond and need to be included in your selection. Water garden plants are called aquatic, because their life cycle revolves around water. Aquatics can be divided into three major categories: emergent, submerged and floaters.
Emergent plants are sometimes also called marginals. These plants are found along the edges of a pond where the roots are attached to the muddy bottom and portions of their stems are above the water. Common examples include cattails, iris and pickerelweed (see list of emergent plants for others). 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. Water lilies fall into this category. Bog plants are also considered to be marginals.
Though most are not grown for their flowers, some, like lotus and waterlilies, are extremely dramatic when in flower. Bog plants are available for those not able to locate their water garden in sufficient sunlight to support good plant growth. Some bog plants can tolerate as little as three hours of sun and still provide interest to the water garden.
Many bog plants grow in constantly moist to soggy soils, while others actually grow in standing water. There are many different species of bog plants with varying heights, textures and foliage colors that add height and drama to water gardens. Lotus, sagittarius, dwarf bamboo, iris, cattails, and sweet flag are some examples (see list).
Submerged plants are those that for the most part remain beneath the water surface. They are often referred to as oxygenators. These plants help combat algae by consuming excess nutrients while at the same time providing cover for fish and producing oxygen during daylight hours. Roots of these plants are not used for nutrient or water uptake, but only for anchorage. Because of this, many oxygenators may be potted in gravel. Submerged plants stocked at the rate of about one bunch per two square feet of water surface area. Caging these plants is sometimes suggested if the pond contains fish, which tend to forage on submerged plant foliage. (See list for suggested oxygenators.)
Floaters are not rooted in the soil, but are allowed to float freely above or below the water surface. Floaters enhance the display of water lilies and lotus as well as adding a finishing touch to the water garden. They are the "ground covers" of the 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. Duckweed, water hyacinth, and water lettuce are examples. (See list for other floaters)