Eichhornia crassipes
Photo: B. PhalanCC BY 4.0
perennial

Water Hyacinth

Eichhornia crassipes

The Story

Plant Bio

Eichhornia crassipes, the common water hyacinth, is a free-floating aquatic perennial of pantropical origin, sitting six to nine inches above the water on rosettes of glossy rounded leaves. Each leaf stalk is swollen into a spongy bladder that keeps the plant afloat, and lilac to lavender flower spikes open from June to September above trailing dark roots.

It is one of the most damaging aquatic weeds in the world, doubling its area in as little as a fortnight and sealing waterways into solid mats that kill the water beneath. It is a federal noxious weed and illegal to possess in several states, so check the law before acquiring it; a hardy water lily gives surface cover with none of the risk.

Uses & Benefits:

Ornamental UsesLilac flower spikes over glossy rosettes floating on the water surface through summer.
Practical UsesShades a closed pond surface quickly and takes up nutrients that would otherwise feed algae.
Ecological BenefitsIn the wild it is destructive rather than beneficial, forming mats that deoxygenate the water below.

Essentials

At a Glance

Plant Type

Perennial

Height

8 inches

Width

12 inches

Light

Full Sun, Partial Sun

Zones

8, 9, 10

Water

Aquatic

Humidity

High

Lifespan

Perennial, grown as an annual in cold regions

Native To

Pantropical; South American in origin

Toxicity

Non-toxic

Planting

How to Grow

  1. Check whether it is legal to keep in your state before acquiring it.
  2. Keep it only in a self-contained pond or tub with no outflow.
  3. Site in full sun on still water.
  4. Thin the mat regularly; it doubles in a fortnight.
  5. Compost surplus plants well away from any watercourse.
  6. Remove and destroy everything before autumn in mild regions.

Pro Tip

Never dispose of surplus plants near water; a single rosette washed into a watercourse is how most infestations begin.

Keep It Thriving

Care Guide

Do

  • Check state law before acquiring it 📋
  • Keep it in a closed pond or tub only 🪣
  • Thin the mat regularly through summer ✂️
  • Compost surplus far from any watercourse 🚫

Don't

  • Release it into any natural water ❌
  • Let it cover more than a third of a pond surface ❌
  • Dispose of it into a drain or ditch ❌

Seasonal Care Calendar

TaskJanFebMarAprMayJunJulAugSepOctNovDec
Clear
Thin

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Contained ornamental pond or tub water gardenSeasonal annual float in cold-winter regionsSurface shading in a closed water feature

Companion Plants

Hardy Water Lily Sweet Flag Pickerelweed Umbrella Plant Marsh Marigold

Multiply

Propagation Methods

Good to Know

Common Questions

Water Hyacinth questions

What zones can Water Hyacinth grow in?

Water Hyacinth is hardy in USDA Zones 8–10. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Water Hyacinth deer resistant?

Yes — Water Hyacinth is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.

When does Water Hyacinth bloom?

Water Hyacinth typically blooms in early summer to early fall through early fall. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Water Hyacinth need full sun?

Water Hyacinth does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.

Keep exploring

Explore the genus

Grow Water Hyacinth with confidence

See it in a design of your actual yard, get zone-matched care reminders, and track it season by season in your garden journal.

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