Common Water Hyacinth Facts, Care, Benefits, & Hardiness (Eichhornia crassipes)
The water hyacinth (Eichhornia crassipes) is a large free-floating plant that inhabits stationary or slow-moving warm waters of tropical and sub-tropical regions worldwide. Water hyacinths have the characteristic thick green leaves of other herbaceous floating plants like frogbit, which can reach 15 cm (6 in) in length. These thick, waxy leaves grow in rosettes around a central stem or petiole that often has a spongy bulbous base that keeps the plant afloat. Water hyacinths can grow up to 1m (3ft) above the waterline with another 15cm (1ft) of roots lurking below the surface.
What sets the water hyacinth apart from other floating herbs is its beautiful bloom of 8 to 15 flowers erupting from a single stalk. Flowers are blue-to-purple in color, usually with a yellow teardrop patch on the top petal. Water hyacinth flowers are dense—each with six petals arranged in an upper and lower semicircle.
Does Water Hyacinth Benefit Ponds & Wildlife?
The water hyacinth is native to the lowlands of South America, most notably the Amazon basin of Brazil, Venezuela, and Peru. Here, it is a favorite of long-tongued bees (Anthophorini tribe in the family Apidae). In North America and Europe, some scientists anticipate that hummingbirds, other native species of long-tongued bees (like carpenter and miner bees), and butterflies may be pollinators of the exotic flower.
Although considered pests in much of the tropics, water hyacinths have several unique uses. Their stalks can be dried and woven into an assortment of goods like baskets, placemats, and furniture. In countries such as Taiwan, Java, and Vietnam, the plant is cooked and eaten. Interestingly, their rapid growth and high nitrogen content make water hyacinths a great source of bioenergy. In certain areas like India and Thailand, they are burned to create natural gas or fermented to derive ethanol. Many backyard gardeners have also found that water hyacinth ashes are particularly good fertilizer.
Common Water Hyacinth Growth & Hardiness
Water hyacinths are one of the fastest growing aquatic plants and can quadruple in size a single month. This means that they can easily spread from one side of your pond to another if not wrangled or regularly trimmed. Water hyacinths are perennials in tropical climates and bloom all year long. In temperate and subtropical climates, however, they are annual plants and bloom during the hottest months of the year, mid-summer to mid-autumn.
Regardless of climate, these flowers are diurnal, meaning they open in the morning and close their petals at night. Each flower lasts about two or three days before withering and sinking into the water. Water hyacinths also only tend to bloom when they are clustered together, meaning single free-floating plants are unlikely to flower. These tropical plants grow best in full to partial sunlight with water temperatures around 21 to 27°C (70 to 80° F). Water hyacinths can tolerate environmental temperatures from 12°C (54°F) to 35°C (95°F), but both frost and water temperatures over 34°C (93°F) will kill the plant. Water hyacinths are sensitive to salinity over 5ppt and can tolerate a pH range from 5.0 to 7.5.
How to Plant Common Water Hyacinth:
To plant your water hyacinths, trim their roots to about 5 cm (2 in) and remove yellow leaves. Then, scatter them on the surface of your pond. To promote flowering, contain the water hyacinths with a circle of tubing, hula-hoop or water hyacinth basket.
How to Care for Common Water Hyacinth:
Dead plant matter—like withered flowers, can degrade water quality in your pond by decreasing dissolved oxygen content and increasing the concentration of waste products. It is important to trim dead stems and skim root pieces that may fall to the bottom, especially if you keep fish. Since water hyacinths can double their size in only two weeks, you should cut back the plant on a weekly basis. Water hyacinths can easily overgrow and take over your entire garden pond, so caring for these plants requires vigilance.
Water hyacinths do best in nutrient rich environments. If you notice your water hyacinth yellowing, simply float them in a vat of water with diluted liquid fertilizer (for 12-4-8 fertilizer 1 teaspoon per gallon or 5 ml per 4L is recommended).
Water Hyacinth Winter Care – Is it Worth it?
These tropical plants do not do well in cold weather. Before the first frost, you should remove your water hyacinths regardless of whether you are overwintering or not to ensure the plant does not die in your pond. Since water hyacinths grow so quickly, many gardeners believe the hassle of overwintering outweighs the benefits. Some people dry their water hyacinth on their lawns and use it as organic fertilizer. You can do so by burning it and mixing it into the soil of your flowerbeds or chopping it with your lawnmower and using it to feed your grass. If you wish to overwinter water hyacinths, simply place a portion of your plant in a tub with at least 15 cm (6 in) of water and either liquid fertilizer or a layer of compost. Position your water hyacinths in an area where it will receive at least six hours of direct sunlight per day.
Is Common Water Hyacinth Toxic, Poisonous or Invasive?
Water hyacinths were first introduced into North America at the 1884 World’s Fair held in New Orleans. By 1894, the water hyacinth had found its way across the world and appeared in Indonesia. In the years since, they have become a major noxious weed in areas of the world that do not see regular yearly frosts. Water hyacinths are illegal in the Australian states of New South Wales and Queensland and in various U.S. states including Alabama, Arkansas, Arizona, California, Florida, Hawaii, Louisiana, Mississippi, South Carolina, Texas, and Puerto Rico. This is not an exhaustive list so always check with your local government before purchasing an exotic plant.
Like other aquatic plants that form large dense mats, water hyacinths can choke out local plant species, decrease dissolved oxygen and nutrient concentrations in the water, and blocking sunlight from penetrating the water’s surface. These plants have also been known to totally obstruct waterways and break off into mats during floods, destroying crops and infrastructure as they travel.
Raw water hyacinths are a skin irritant and may cause severe itching. Additionally, water hyacinths can pick up heavy metals and other pollutants from the water and may become poisonous simply by accumulating these toxins.
Will Koi & Pond Fish Eat Common Water Hyacinth?
There is some suggestion that raw water hyacinths may be toxic to dogs, cats, and horses. On the other hand, Stinkpot (Stenotherus odoratus) and Slider (Trachemys scripta) turtles enjoy feeding on water hyacinth leaves while fish may nibble on the long roots.