Hardy Water Lily

• The hardy water lily (Nymphaea) can handle Illinois winters as long as the water doesn't freeze all the way down to the roots. This Nymphaeaceae plant family member prefers fully sunny positions but can flower with just three hours of direct sunlight each day. Mature plants range from 3 to 6 inches in height with spreads reaching up to 6 feet. Hardy water lilies feature rounded, green leaves that float on top of the water's surface. Flowers bloom continuously from May through the first frost, with each flower blooming for just five days. These flowers have yellow-pink petals surrounding yellow center stamens. Aphids and mining midges sometimes feed on these plants.
  
  

Sacred Lotus

• The sacred lotus (Nelumbo nucifera) grows well in Illinois water gardens if the roots don't freeze in the winter. Native to Asia and northern Australia, this water plant prefers rich, loamy soils that receive full sun. The sacred lotus bears rounded green leaves that rise above the water. Large, fragrant white or pink flowers appear from July through September. Each flower only blooms for three days. These flowers give way to nutty fruits that you can use in dried flower arrangements. This Nelumbonaceae family member reaches 3 to 6 feet in height and 3 to 4 feet in width. Blights, red spider mites and aphids sometimes affect these plants. Plant the sacred lotus in water garden margins.
  
  

Sweet Flag

• The sweet flag plant (Acorus calamus) typically performs well in Illinois water gardens that receive full sun to partial shade. Although a member of the Acoraceae family, this plant has sword-shaped, green leaves similar to irises. The foliage is fragrant when crushed or bruised. Non-showy, green flowers appear just beneath the leaf tips late in the spring. These tiny flowers give way to small berries. While this plant has no serious pest problems or diseases, scorch can harm plants that are not kept in consistently wet soils. Use sweet flag as an accent plant in your water garden.
  
  

Marsh Marigold

• Despite its name, the marsh marigold belongs to the buttercup plant family (Ranunculaceae) and not the marigold family (Asteraceae). Marsh marigolds (Caltha palustris) naturally occur in swamp, stream and marsh margins in the northern temperate regions of North America. This water garden plant prefers shallow edges that receive full sun to partial shade. Mature marsh marigolds range from 12 to 18 inches in height with similar spreads. Vibrant yellow flowers appear from April through June and then give way to seed pods. The long green leaves don't mature until after the plant is through flowering. Watch your marsh marigolds for rust and powdery mildew.