Although it is thought that water hyacinth cannot survive Washington's winters, its presence as an ornamental makes it possible for escape and growth in the wild. Water hyacinth does survive freezing conditions in other states where it is established and it may be possible for this plant to survive western Washington's relatively warm winters. Growth Habit Water hyacinth can form impenetrable mats of floating vegetation. It reproduces by seeds and by daughter plants which form on rhizomes and produce dense plant beds. In one study, two plants produced 1,200 daughter plants in four months.
Individual plants break off the mat and can be dispersed by wind and water currents.
As many as 5,000 seeds can be produced by a single plant and these seeds are eaten and transported by waterfowl. Seedlings are common on mud banks exposed by low water levels. Management Water hyacinth is controlled through a number of methods including harvesting, aquatic herbicides, and biological control agents. In Washington the best way to manage water hyacinth is to prevent it from becoming established. It is thought that these plants have been discarded by somebody cleaning a backyard pond.