Midwest Noxious Weed: Do Not Plant
Common Name: common water hyacinth
Type: Herbaceous perennial
Family: Pontederiaceae
Native Range: Pantropical
Zone: 9 to 11
Height: 0.50 to 0.75 feet
Spread: 0.50 to 1.50 feet
Bloom Time: June to September
Bloom Description: Lilac to lavender
Sun: Full sun
Water: Wet
Maintenance: High
Suggested Use: Annual, Water Plant, Naturalize, Rain Garden
Flower: Showy
Culture
A frost-tender aquatic perennial that is winter hardy to USDA Zones 9-11 where it can be quite invasive. In St. Louis, it will generally not survive winter and is often grown as an annual. It is easily grown on still water in full sun. Needs hot summer weather and full sun to bloom. Scatter small bunches of plants on the water surface after last frost date. Plants spread quickly in optimum conditions by stolons that radiate outward from the mother plant. Remove excess plants as needed. Several plants may be lifted in fall before frost for overwintering in containers of wet, sandy loam in bright light at indoor temperatures of 60-70°F. However, many St. Louis gardeners prefer to grow water hyacinth as an annual by simply repurchasing new plants each spring.
Noteworthy Characteristics
Eichhornia crassipes, commonly called water hyacinth, is native to Brazil. It is a free-floating, frost-tender aquatic perennial that is commonly used as an ornamental plant in water gardens. It produces rosettes of thick, leathery, ovate to rounded, glossy green leaves with inflated, bulbous leaf petioles that act as floats. Plants spread rapidly by stolons to form a dense mat of foliage (to 6” tall). Spikes of lilac to lavender flowers bloom atop erect stalks to 6-9” tall in summer. Each flowering spike typically has 8-15 flowers. One petal of each flower has a yellow spot at the base. Long greenish-purple roots dangle downward from the plants, providing shelter and spawning areas for many small fish. As an ornamental water garden plant, water hyacinth provides attractive flowers and dense foliage that inhibits growth of algae and helps keep water clear. The value of this plant is directly related to the climate in which it grows. In warm climates where it survives winter, water hyacinth is considered to be a noxious weed because of its ability to rapidly cover a pond or lake from shore to shore and to choke waterways. It has naturalized in the deep South in states such as Florida, Louisiana and Texas where expensive eradication programs have been implemented. It is included on the Federal List of Noxious Weeds. Several southern states have banned its sale. On the other hand, in areas where the plants are not winter hardy, they are being purposefully introduced into wastewater areas to clean up the water because they not only absorb many common pollutants but also absorb some toxic pesticides and heavy metals. Steyermark reports small populations in the Southeast lowlands area of Missouri.
Genus name honors J. A. Fr. Eichhorn (1779-1856), Prussian minister of education.
Specific epithet means thick-footed or thick-stemmed.
Problems
No serious insect or disease problems. An invasive species in mild winter climates.
Uses
Free floating aquatic perennial for water gardens or ponds.