Common water hyacinth (Eichhornia crassipes)
Eichhornia crassipes, the Common water hyacinth, is a floating aquatic perennial prized for lilac blooms, though highly invasive in warm zones.
Complete Plant Information
Overview
Eichhornia crassipes, widely known as Common water hyacinth, is a highly recognizable, free-floating aquatic perennial famous for its attractive foliage and spikes of showy, lilac-to-lavender flowers. The plant is easily identified by its thick, leathery, glossy green leaves supported by bulbous, inflated petioles that provide excellent buoyancy on still water. While valued ornamentally, this species demands high maintenance because of its aggressively spreading nature.
Native to Brazil, this plant thrives in hot, full-sun conditions, using stolons to expand rapidly across the water surface, forming dense mats. In its tropical and sub-tropical native range, Eichhornia crassipes is a significant invasive species capable of choking waterways entirely. Gardeners in areas outside of Zone 9 must treat it as an annual, enjoying its filtration benefits seasonally before frost claims it.
The draping, greenish-purple root systems of the Common water hyacinth offer vital shelter and spawning areas for small fish. This dense structure also passively assists in water clarity by suppressing algae growth. Successful cultivation requires monitoring its growth rate constantly to ensure it remains an asset rather than a liability in any water feature.
Fast Facts
- Plant Family: Pontederiaceae
- Plant Type: Herbaceous perennial
- Native Range: Pantropical
- Hardiness Zones: USDA Zones 9-11
- Size at Maturity:
- Height: 0.5-0.75 ft
- Spread: 0.5-1.5 ft
- Bloom Time: June to September
- Bloom Description: Lilac to lavender
- Sun Exposure: Full sun
- Water Needs: Wet
- Maintenance Level: High
How to Grow
The ideal time to introduce Eichhornia crassipes to your water garden is immediately following the last expected frost date. This frost-tender aquatic perennial requires still water and consistently hot summer weather to initiate robust blooming. Simply scatter small bunches of the plants onto the water surface where they will anchor themselves securely in the water column.
Maintenance for Common water hyacinth is classified as high due to its rapid replication via radiating stolons. Regular removal of excess plants is mandatory to prevent them from completely covering the water surface, which would block light and oxygen for aquatic life below. If you live outside Zones 9-11, plan to overwinter desirable specimens indoors.
To prepare plants for winter, carefully lift several healthy specimens before the first frost. Overwinter them in containers filled with wet, sandy loam, ensuring they receive bright indoor light and maintain temperatures between 60–70°F. Alternatively, many gardeners outside the perennial range prefer the simplicity of treating water hyacinth as an annual, purchasing new plants each subsequent spring.
Landscape Uses
As a recommended aquatic perennial, Common water hyacinth is perfectly suited for use in water gardens, ponds, and deliberate rain garden installations where water retention is necessary. Its free-floating nature allows it to colonize still water surfaces beautifully, creating a living, floating carpet that contrasts nicely with submerged marginal plants.
When used ornamentally, the plant’s aesthetic appeal lies in its contrast: the bright, lush foliage above the water and the dangling roots below supporting fish populations. When grown intentionally as an annual in colder climates, gardeners can use it as a dynamic, temporary floating centerpiece. Because the plant aggressively colonizes, it works best in isolated, contained water features rather than large, open bodies of water where naturalization is undesirable.
Standout Features
Flower Qualities
- Showy
Noteworthy Characteristics
Eichhornia crassipes, commonly called water hyacinth, is native to Brazil and functions as a free-floating, frost-tender aquatic perennial ideal for water gardens. Its structure includes rosettes of thick, glossy leaves with inflated petioles that act as buoyant floats, spreading quickly by stolons to form dense surface mats. Spikes rising 6-9” tall feature 8-15 lilac-to-lavender flowers, each marked by a distinctive yellow spot, while its dangling roots shelter small fish. Although prized for appearance and water filtration, in warm climates, its ability to choke waterways renders it a noxious weed included on the Federal List of Noxious Weeds.
Tolerances
- No serious insect or disease problems.
Potential Problems
The primary issue associated with Eichhornia crassipes is its highly invasive nature in mild winter climates, where it has naturalized across the Deep South. When allowed to spread unchecked, this Common water hyacinth can rapidly cover ponds and lakes shore-to-shore, leading to ecological damage and waterway obstruction. In areas unsuitable for winter survival, the plant is typically easy to manage as an annual. If you live in Zones 9-11, proactive and diligent removal of excess growth throughout the season is essential.
Frequently Asked Questions
What hardiness zones is Common water hyacinth suitable for?
Eichhornia crassipes is winter hardy in USDA Zones 9 through 11, but it is commonly grown as an annual where winter temperatures drop below this range.
How large does Eichhornia crassipes grow?
When mature, the Common water hyacinth typically reaches a height between 0.5 and 0.75 feet, spreading horizontally from 0.5 to 1.5 feet via stolons.
What sun exposure does Common water hyacinth need?
This aquatic perennial requires full sun exposure, along with hot summer weather, to produce its best blooms between June and September.
When does Water hyacinth bloom?
Water hyacinth blooms from June through September, displaying spikes of attractive lilac to lavender flowers atop erect stalks.
Conclusion
The allure of the Common water hyacinth lies in its lush texture, rapid mat-forming capability, and beautiful summer blooms, offering functional benefits like water filtration in contained settings. While beautiful, the aggressive growth of Eichhornia crassipes demands high management, especially in warmer zones where it spreads rapidly. Before introducing this plant to your water feature, verify your local climate hardiness and be prepared to dedicate time to regular thinning.
Companion Planting
Since the Common water hyacinth occupies the top layer of the water surface, companion planting involves selecting species that utilize different water levels or offer a stark aesthetic contrast. In water gardens where its spread is contained, consider placing it near emergent plants like Arrowhead (Sagittaria spp.) or cattails (Typha), which anchor to the bottom substrate. Submerged oxygenators, if they can receive residual light, can also help maintain water quality without competing directly for surface space.
Seasonal Care Calendar
For gardeners enjoying Eichhornia crassipes as an annual, scattering new plants onto pond surfaces should occur only after the danger of frost has completely passed in late spring. Throughout the summer, dedicated effort is required for population control, as plants multiply quickly by stolons; remove excess bunches weekly if necessary to maintain desired coverage. In early fall, before the first predicted frost, carefully lift any mature plants you wish to save for indoor overwintering, disposing of the rest before they die back.
