These underwater plants are very important to the pond ecology. They contribute to clear water and are sometimes referred to as “nature’s filter”. To be the most effective, they should be stocked at the rate of one bunch per one to two square feet of pond surface area or one bunch for every 12 to 24 gallons of water.
Typical planting method for submerged plants is to hold the base of the plant down, using gravel or stone in a pot. They must be held down because they are buoyant. Since it is an unnatural growing position, they are not nearly as effective floating on the top of the water.
Besides helping water quality, these plants provide cover and protection for adult and baby fish. Goldfish will spawn on these plants, attaching eggs to the foliage where they soon hatch. Fish fry will be hide from adult fish among the plant’s leaves until they can grow large enough to fend for themselves. Stock early to be able to get all benefits of these important plants. Each plant cools the water by making shade. Stick your hand into the plant on a hot summer day and feel the difference in temperature.
Submerged oxygenator plants, like Anacharis and Hornwort, are sold as bare root cuttings, the stems held together by a rubber band. The plants must be planted in a pot of gravel or weighted to the bottom with larger stones, so they can take nutrients from the pond directly through their foliage.