Thalia dealbata

Named after the German physician Johannes Thal, this is a great plant for a water garden.  Plant in 12 to 18 inches of water over the crown or in 5 to 20-gallon tubs.  Its native habitat includes cypress swamps, marshes and ponds.  Locating your plants in 18 to 24" of water during the winter months is sufficient.  Cutting back and providing a thick layer of mulch will help the plant to winter well.  If not possible, locate in a frost free location during the winter months.  A greenhouse is ideal, protecting from frost and providing sufficient bright light.   

The entire plant is covered with a white powdery coating, thus the common names, Powdery Thalia and Powdery Alligator-flag.  This powdery substance is water-repelling and also adds muted coloration, enhancing the plants appearance.  

The petioles and basal sheath have internal air cavities, making them buoyant.  

After blooming, the flowers are replaced by smooth seed capsules, each containing 1 seed.  

Under the right conditions, the spreading rhizomes can create a quite large colony of plants.  In locations where the correct growing conditions are absent, this plant is considered endangered.  

Hardy canna is a valuable plant for the environment.  It goes through a natural process called Phytoremediation, which breaks down or removes excess pollutants from standing water. This improves the water quality.

Insects, Diseases, and Other Plant Problems:  No insect or disease issues.  Its spread through rhizomes can be invasive.