There are all types of plants you can add to your water garden. Among the best are the "floaters." Here are some of our favorites.
WATER LETTUCE (Pistia stratiotes) Also called shellflower, this plantís deeply creased, lime-green leaves form heads vaguely resembling lettuce. Water lettuce spreads by plantlets that break off from the mother plant, making them ideal for most water gardens. Mature plants can stretch 6 inches across and form a colony several feet wide by summer's end. Growing it is prohibited in some states because it can become a nuisance. Easy to grow in most climates, water lettuce can be tricky in cool water and low humidity. It prefers warm water and is thus an excellent selection in shallow ponds and containers. Plant it in partial shade for the best color and growth, although it will tolerate full sun. Treat water lettuce as an annual in most parts of the country, since it is hardy only in zones 9 - 10.
WATER HYACINTH (Eichhomia crassipes) Water hyacinth produces lovely blue midsummer blossoms on short, 6 to 8-inch spikes that grow above leathery, rounded leaves. It spreads rapidly and is invasive in warm parts of the country and has been banned from some areas. It is killed at the first frost. Its trailing roots make good spawning grounds for fish and a nice salad for koi. It is outstanding as a vegetative filter. Water hyacinth likes full sun and is treated as an annual in most parts of the country. It is winter hardy only in zones 9 - 10.
DUCKWEED (Lemna spp.) This is a vigorous plant with thin, tiny, angular, or clover-like leaves that hang just below the water surface. It is a prized source of food for goldfish and koi. Duckweed shades the water surface well, and it tends to thin out slightly in summer's hottest weather. Ivy-leaf duckweed (L, trisulca) is the smallest-leafed and least invasive. Skim out excess plants in small ponds as needed. Avoid other varieties. L. minor, for example, is extremely prolific and is found in stagnant natural ponds everywhere. Thick duckweed (L. gibba) and greater duckweed (Spirodela polyrrhiza) are also very invasive. Duckweed has a broad range of hardiness, growing well in zones 2 - 11.
FAIRY MOSS (Azolla spp.) Also called water fern, this is one of the most widely available floaters. Its tiny fronds, about Ĺ-inch across, spread rapidly and form dense, pale green clusters that fish love to graze upon. Fronds turn red in summer. Fairy moss can be invasive, so use it only in ponds where itís possible to control by netting. Although it is hardy to zone 7, it will die if the water freezes. In colder areas, save some in a jar filled with water and soil, and reintroduce it to the pool the following spring. A. caroliniana is the most commonly available variety. It grows in sun to partial shade and is hardy in zones 7 - 10.
SALVINIA (Salvinia rotundifolia) Sometimes called water or butterfly fern, the leaves of these tiny plants form layers of ruffles along the length of the stems. The small, floating leaves are pale green or purplish-brown and covered with fine silk-like hairs. Salvinia grows in large, floating colonies and can become invasive. Thin it regularly by netting. Plan on a heavy thinning early in the summer because salvinia thrives especially well in hot, sunny conditions and can quickly grow out of control. In most regions, water gardeners use salvinia as an annual because it is hardy only in zones 10 - 11.
FROGBIT (Hydrocharis morsus-ranae) Its tiny flowers measuring about Ĺ-inch across resemble small, white water lilies. Frogbit leaves are kidney-shaped, veined, shiny, and about 1 inch across. The foliage dies back in autumn and the plants survive as dormant buds on the bottom. Growth begins again early the following summer. Frogbit spreads by runners, but its growth is restrained. It likes calm, shallow water about 1 foot deep, and it may root in mud. You can over-winter the buds in a jar filled with water and soil, replanting them in spring. This plant likes full sun but is treated as an annual in cold areas, since it is hardly only in zones 7 - 10.
As you can see, there are a lot more readily available water plants than you might ever have thought. In truth, there are far more still that we havenít touched upon because either theyíre not easily obtainable or theyíre more difficult to grow in an artificial environment.
Whatís most important of all to remember when introducing water plants into your aquascaping is that you must meet the plantsí needs first; donít try forcing a round peg into a square hole (or a marsh pickerel into a water lettuce). Each plant has its own needs and place in the garden, and if you honor them the way you would your favorite grandmotherís last wish, youíll have success beyond your wildest dreams.