By Josh Spece
Common Name: Water Hyacinth
Latin Name: Eichhornia crassipes
Hardiness: zone 9 (20*F)
Light: Sun for best flowering and compact growth, but will grow just fine in shade.
Size: 6 in. to 2 feet or more
Notes: Water hyacinths are one of the most common plants seen in water gardens. This floating plant is native to South America and very sensitive to cold weather. Water hyacinths have round, glossy green leaves held on upright, fleshy stalks. Short plants usually have a large “ball” at the base of each leaf. This, along with the fleshy stem, is filled with styrofoam-like material that keeps the plant afloat. Beneath the water is a large, feathery root system that is usually black or purple.
Water hyacinths are very useful at competing with algae. Their fast growth rate allows them to quickly shade the water while at the same time absorbing huge amounts of nutrients from the water.
Hyacinths are usually very easy to grow, but some people have trouble getting them to grow and bloom. Fish love to nibble at the roots. If the fish are large or there are a lot of them, they may kill the plant or even eat the entire thing. Placing the hyacinths in floating baskets or partitioning them off from the fish with rocks may help.
Water hyacinths love to be crowded and even though they are floating plants, they don’t like to drift around. Corralling them with a hoop of plastic tubing, a hula-hoop, fishing line, or even rocks will keep them from moving around.
Water hyacinths usually bloom the most during the hottest part of the year and only if they are crowded. Each 6” to 12” flower spike lasts only one day and has 6 to 15 lavender flowers on it.
Yellowing hyacinths are a common problem and it is caused by lack of nutrients. Hyacinths are such vigorous growers they sometimes use up one or more nutrients in the pond. This can especially be a problem in very small ponds and ponds with very few fish. There are two ways of fertilizing your hyacinths. If you only have a few hyacinths, you can float them in a bucket of Miracle Grow for a few hours at a time. If you have too many hyacinths to remove from the pond, you can treat the entire pond with a solution of Muriate of Potash. Flora Boost is a commercially produced potassium supplement. Hyacinths and other floating plants also usually respond well to any of the micro nutrient solutions specially made for pond plants.
A more common problem is water hyacinths growing too well and crowding out other plants. In ideal conditions, water hyacinths can double in mass in as little as 6 to 14 days! In a small backyard water garden, it is easy enough to just remove excess hyacinths as needed. In areas that remain frost-free year round, water hyacinths are considered a major pest. Many southern states have banned them completely. For this reason it is very important never to place water hyacinths in a natural body of water!!
Varieties: There are very few varieties of water hyacinth and none of them commonly available. The Peacock Water Hyacinth (Eichhornia azurea) is very similar to the common variety. It remains smaller and forms a creeping mat on the water surface. The plant lacks the swollen stems of the common hyacinth. May prefer to be potted in soil as opposed to free floating. The Peacock Hyacinth is said to be freer flowering with more attractive blooms than the common species. There is also a white flowered water hyacinth, but it is very rare.
Winter Care: Trying to overwinter water hyacinths in cold regions is usually more hassle than it’s worth. They are cheep enough and grow fast enough during the summer that it is usually easier and more cost effective to buy new ones each spring. If you want to try keep hyacinths over winter they need a warm spot that is brightly lit. A South window is best, but artificial lighting may still be necessary. Fluorescent shop lights 6” above the plants is about right. Some people have reported success by putting a couple inches of compost in the bottom of the container the hyacinths are in. Others actually pot the hyacinths and submerge the pot so the rim is an inch or two below the water surface.
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