In the Gulf Coast region Hyacinth spread like mad, and are a problem of major proportions, even to the point where some states like Florida have laws against propagation or even possession. North of zone 8 the situation is different, because these plants are tropical and killed by a hard frost. For any pool or small pond with an abundance of fish and the fertilizer they provide, hyacinths are almost a necessity, because their nutrient eating capacities really help control floating algae and improve the water quality for the fish.

They can be over wintered in cold climates by floating them in a one gallon or larger container in front of a sunny window. Put some dirt in the bottom of the container for fertilizer, or the plants will yellow and die. The water temperature should be kept between 70 and 80°. Return them to the pond as soon as the temperature reached 70° and you are past the danger of frost.

How To Identify Water Hyacinth

Water hyacinth is a free floating plant, Native to South America, which grows up to three feet in height. It has thick, waxy, rounded, glossy leaves, which rise well above the water surface on stalks. The leaves are broadly ovate to circular, 4 to 8 inches in diameter, with gently incurved sides, often undulate. Leaf veins are dense, numerous, fine and longitudinal. Water hyacinth leaf stalks are bulbous and spongy. Water hyacinth grows an erect thick stalk (to 20 inches long) at the top of which is a single spike of several (8 to 15) showy flowers. The flowers have 6 petals, purplish blue or lavender to pinkish, the upper petals with yellow, blue-bordered central splotches. Water hyacinth reproduces vegetatively by short runner stems (stolons) that radiate from the base of the plant to form daughter plants, and also reproduces by seed. Its roots are purplish black and feathery. (University of Florida, IFAS, Center for Aquatic Plants)

 

PROBLEMS

Yellowing: hyacinths do not die from too much sun. There are a couple of things that usually cause leaf yellowing on hyacinths and other water plants. Insects can cause the plants to yellow. Aphids in particular will cause yellowing of the leaves as they suck the juices from the plants. If aphids are the cause, you can swish the leaves of the plants in the water and let the fish feed on them. Another solution is to remove the plants from the pond and spray them with a commercial insecticide like Sevin. Let the spray dry on the plants and then hose the plant lightly with a steady spray from the garden hose then replace them in the pond. Any small amount of insecticide left on the plant will not harm the fish. 

More often than not the yellowing is due to lack of fertilizer. Hyacinths are heavy feeders. Every couple of weeks remove them from the pond and place them in a suitable container with water soluble fertilizer diluted to the manufacturer's directions. Let them soak for several hours and then rinse the roots in plain water and return them to the pond. You will see a remarkable difference in the plants. Incidentally, they will grow faster and bloom more profusely if fertilized regularly. 

Blooming: The most common complaint heard about water hyacinths is that they do not bloom. Again the problem is most likely a lack of fertilizer. Given enough fertilizer they will bloom. Another possible solution to a lack of fertilizer is increasing your fish population. If you have enough available oxygen in the water, increasing the number of fish in your water garden will provide more fertilizer for the plants.

Over Population: as noted below, water hyacinth, given the right conditions, can reproduce at a prodigious rate, and can crowd out other plants and cause imbalances in water conditions. Most people having hyacinth in small pools or ponds are forced to thin them on a regular basis, sometimes as often as once a week.

Water Hyacinth grow naturally in rivers where the water moves all of the time. They do best if you keep them in or around your waterfall, or near a fountain so that they have moving water around them. 
University of Florida, IFAS,
Center for Aquatic Plants

http://aquat1.ifas.ufl.edu/myaqpic.html
Invasive Nonindigenous
Plants in Florida

varamey@nervm.nerdc.ufl.edu
Copyright 1997 University of Florida

Water hyacinth (Eichhornia crassipes) is one of the worst weeds in the world -- aquatic or terrestrial. Until only a few years ago, this floating plant was a major problem in Florida (as it still is in many places throughout the world) covering as many as 125,000 acres of water: boat traffic on several rivers was halted; hundreds of lakes and ponds were covered from shore to shore with up to 200 tons of hyacinths per acre!

This South American native was introduced into Florida in the 1880s. Its growth rate is among the highest of any plant known: hyacinth populations can double in as little as 12 days. Besides blocking boat traffic and preventing swimming and fishing, water hyacinth infestations also prevent sunlight and oxygen from getting into the water. Decaying plant matter also reduces oxygen in the water. Thus, water hyacinth infestations reduce fisheries, shade out submersed plants, crowd out immersed plants, and reduce biological diversity.


Copyright 1998
University of Florida

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