Water hyacinth is a weed that is growing fast. Can breed easily by branching. Or from seed, which has as many as 300 seeds per flower seeds last for up to 5-20 years and will grow well in stagnant water. The results of the study reported that the canals will increase from 10 at the beginning of a six within just eight months each clump can be expanded by as much as one takes only 15-20 days.