The water hyacinth (Eichhoria crassipes) is a blooming pond plant that was introduced to the United States in 1880 from South America. It primarily thrives in the Southern states, where it has become invasive in places. This plant floats freely in ponds, estuaries and lakes. It grows up to 3 feet tall and its flowers are light blue to violet in color that grow on spikes above its rounded, dark green, fleshy leaves. If you choose to grow water hyacinth, be careful that it doesn't take over your entire pond because it can deplete the oxygen that fish need to survive.
Consider growing your water hyacinth in a large pot with no drainage hole if you live in a Southern state. If you live farther north, especially in a climate zone where winter temperatures dip below 65 degrees Fahrenheit, you can grow it in a pond, but this plant will die in the colder season. To plant it, simply throw your plant(s) into the water.
Provide strong light, which can be delivered by either full natural sunlight or a broad-spectrum grow light. If you grow water hyacinth in a shady pond, it will not do well.
Introduce fish to your pond or pot to help fertilize your water hyacinth. Alternatively, supplement the water with an aquatic fertilizer if their leaves turn yellow. You can purchase aquatic fertilizer from retail stores such as hardware stores and garden shops. Typically, aquatic fertilizer has an N-P-K ratio of 8-24-8. Follow label instructions for best results. Growers suggest that you fertilize frequently by using small quantities of fertilizer.
Prevent the spread of water hyacinth by tying a string 2 inches above the water around their growing area. Periodically pull the string to remove excess plants, which can rapidly spread and choke out your entire pond.
Add your excess water hyacinth to your compost pile---some gardeners grow this plant solely for the valuable nutrients it adds to compost.