Water Hyacinth: A Beautiful but High-Maintenance Water Plant

Scientific Identity

Water hyacinth (Eichhornia crassipes, now also classified scientifically as Pontederia crassipes) is a floating aquatic plant in the family Pontederiaceae, native to the Amazon basin in South America. Its bulbous, spongy leaf stalks let it float easily on the water's surface, and its lavender-purple flowers with a yellow marking open in a vertical spike. Its roots hang down into the water, providing shelter for small aquatic organisms.

Permaculture Value

Water hyacinth does have some genuine benefits: its root system can absorb heavy metals and excess nutrients from water, acting as a natural biofilter, and its biomass can be used as compost or green fertilizer. However, left unchecked, this plant becomes one of the most invasive aquatic species in the world (it appears on the IUCN's list of the 100 worst invasive species). Under favorable conditions its population can double within a few weeks, completely covering the water's surface, blocking light penetration, depleting oxygen levels, and smothering other aquatic plants, fish, and amphibian populations. For this reason, it should only be kept in a permaculture garden within a closed system with no outflow, and with regular intervention - an unchecked 'benefit' can quickly turn into a problem that dominates the entire ecosystem on its own.

Medicinal/Edible Properties

In some regions, the roots and leaves are traditionally used as animal feed (particularly for pigs, geese, and ducks); its capacity to absorb heavy metals and pollutants has also made it a subject of wastewater treatment research. It has no widespread use for human consumption; it's best not to consider this plant for food purposes.

How to Grow (and Control)

Water hyacinth grows extremely fast in warm, sunny, still water. If kept in the garden, it must be kept in a closed container or pond with no outflow, and should never be released into a natural lake, river, canal, or irrigation system - releasing this plant into the wild is already banned in many countries. At regular intervals (weekly or biweekly), excess plants should be hand-removed, keeping coverage to no more than 20-30% of the water's surface. Removed plants should be fully dried in the sun away from any water source before composting; fragments can re-root, so burying them directly in soil or discarding them near water is not safe.

From the Garden

In our pond, water hyacinth is genuinely beautiful but somewhat invasive; we have to keep it under constant control. We regularly remove the excess growth and don't let it cover the whole pond - this way we get to enjoy the flowers while keeping the balance for the other plants and creatures in the pond.