Stocking a water garden with plants and flowers is the fun part of building a pond. There are so many choices. Hardy fresh water plants live from season to season by going dormant or dying back to the roots of the plants and then growing again when the weather warms up in the spring. Tropical plants are killed by cold weather and must be replaced or brought inside.
It's difficult to imagine a water garden without water lilies. Tropical water lilies look the same as hardy water lilies. They have the same cup-shaped flower floating on top of the water surrounded by round leaves up to eight inches across. The difference is that tropical water lilies are scented. They also bloom in more colors, including blue and purple, as well as pink, yellow and white. Additionally, only tropical water lilies have varieties that bloom at night. Remove the water lily tuber when the temperature drops below 50 degrees Fahrenheit and keep in a cool place in damp sand. Replant in the spring. Water lilies go dormant in mild winter areas even if they're kept in the pond.
The tubers of taros are edible and are a major food source for some tropical cultures. It is the basis for Hawaiian poi. The plants have arrow-shaped leaves on tall stems. Some of the leaves may be up to 24 inches long, while the plant grows up to 48 inches tall. There are smaller and shorter varieties more suitable for home pond gardens. Black magic taro has purple leaves so dark they look black. Red stem taro has red stems. Dwarf jade taro only grows three feet, so may be a better fit for smaller water gardens. Violet stem taro has violet stems and blue-green leaves. Either replant with fresh tubers in the spring or overwinter the plants.
The umbrella palm has tall stems up to two feet with an umbrella of narrow leaves at the top of each stem. It is a bog plant and prefers no more than six inches of water over its roots. Unlike water lilies and taro, it doesn't go dormant in the winter where it's warm but keeps on growing, just a little more slowly.
The flowers of the lotus plant look like water lilies but are held on stems up and out of the water rather than floating on the water's surface. The leaves are large with the edges turned upward. Flower colors include white, pink and yellow. Some varieties are tipped or streaked with another color. The seed pods add interest to dried flower arrangements.