Water Hyacinth Facts, Care & Planting Guide (Eichhornia crassipes)


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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.

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Water Hyacinth Fact Sheet:
PLANT TYPE
Tropical Herbaceous Plant
HARDINESS ZONES
USDA 9-11
LIGHT REQUIREMENTS
Full or Partial Sun
BLOOM COLOR
Lavender
BLOOM PERIOD
July – September (Summer)
MAXIMUM GROWTH
Up to 1m (3ft) in height
PLANTING DEPTH
Water’s surface
WATER QUALITY
pH 5.0-7.5

Common Water Hyacinth Growth & Hardiness

water hyacinth benefits for ponds

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:

Many purple water hyacinth blooms in a pond

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:

Water hyacinth growing in a pond

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 hyacinth can be invasive and become overgrown

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 toxic 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.

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19 thoughts on “Water Hyacinth Facts, Care & Planting Guide (Eichhornia crassipes)”

  1. When I was a kid in south Florida we knew water hycinths concealed gators and cottonmouth moccasins, so we steered clear of them.

    Reply
    • Hi Raquel,

      Is the vase too large/heavy to simply tip over and pour the water out while gently holding onto the hyacinth? This is generally the best method and works quite well. Otherwise, you could get creative and try using something like a turkey baster to suck the liquid out bit by bit, and then add in fresh lukewarm water after.

      Reply
  2. Does the waterhyacinth blooms only on the young plants or also on the older ones? I want to avoid trimming back the ones that do bloom. Thank you.

    Reply
  3. hello

    i am here to state you that my water hyacinth have started to get mini red bugs. Can you please help me to kill them forever? Thank you !

    Reply
  4. I loved these in my Koi pond this year. They have kept the water so nice and clear and offered the best shade for the fish.

    Without having to bring them inside for the winter is there a way I can get some seeds or bulbs from the ones I have for next year?

    Reply
    • Hi Dave,

      Thanks for reading, and apologies for such a late reply!

      Yes, you can absolutely harvest water hyacinth seeds without bringing the entire plant indoors during the winter! Water hyacinth will usually form seeds pods between April and September, depending on the zone. You’ll want to wait until the pods are dry and brown, as this is when the seeds are ready to be harvested. Pods may split open on their own, or you can just split dry pods open gently by hand. You can store them in a cool, dry place to dry out for a couple of weeks. You can then transfer them to a dry, sealed jar and store them over winter somewhere cool. Storing in a fridge is an option, but not really necessary unless you’d like to store them long-term (for longer than a season or two). When ready, you can plant directly in soil in the spring, or to encourage propagation you can place the seeds in warm water for about 24 hours to help them soften up a bit, and then place in damp paper towel in a baggy or container in the fridge until they begin to sprout (usually within a few days). Once they sprout, plant!

      If you want to harvest bulbs, simply dig around the plant as deeply as you can (to avoid potentially cutting or damaging the bulbs). Once you remove enough dirt, you should see multiple bulbs – each water hyacinth plant should have a larger, main “parent” bulb and a couple of smaller ones. You should be able to gently peel the smaller bulbs off of the large one. From there, store them in a cool, dry place for the winter and plant in the spring! Take care to not wash them or store where there is moisture, as the bulbs are likely to develop rot.

      A couple of notes: growing from bulbs will result in water hyacinths that are clones of the parent hyacinth, meaning they will look very similar. Growing from seed has a greater likelihood of resulting in plants that are different colors and proportions than the plant they were harvested from.

      Reply
  5. Are water hyacinth ok to put in my pond? We have wild horses, deer and elk. They will freeze but I don’t want to harm the game. Any thoughts?

    Reply
    • Hi John,

      Sorry about the delayed response!

      Water hyacinth can be toxic in large quantities, but you can still have it in your pond if you place them in aquatic planting baskets toward the deeper parts of the pond that the wildlife are less likely to be able to get to. The baskets will help keep them in place and slow their spread.

      Reply
  6. We have a wonderful collection of water hyacinths in our koi pond. The one issue we have now is that they never seem to bloom any longer. Because they have bloomed in the past, we are uncertain of the problem. Typically we begin the season with maybe 4-5 hyacinths. After maybe the middle of the season, they have multiplied into several hundred. With our lilies, all of which bloom, we have plants covering perhaps 2/3 of our pond (roughly 10 x 15 feet). All plants look healthy as do our three kois.

    Reply
    • Hi Richard,

      Sorry about such a late reply!

      When your water hyacinths have bloomed in the past, did the pond have similar plant coverage? It could be an issue with overcrowding. It might also be a nutrient issue – have you checked nutrient levels? Water hyacinths tend to do best in nutrient-rich environments, as they’re excellent at soaking up and utilizing excess nutrients for growth and blooming. Alternatively, has the amount of sun that they receive changed? While they can do well enough in partial sunlight, full sun tends to elicit the most blooms.

      Reply

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