Repotting guide

When & how to repot Eichhornia crassipes (Eichhornia crassipes)

Also called Water Hyacinth, Common Water Hyacinth.

More about eichhornia crassipes

About Eichhornia crassipes

Eichhornia crassipes · also called Water Hyacinth, Common Water Hyacinth · flowering

Eichhornia crassipes is a free-floating tropical aquatic with glossy rounded leaves on spongy, inflated petioles that keep it buoyant, and showy lavender-blue flower spikes marked with a yellow eye. It multiplies explosively across warm, still water. Useful for shade and filtration in summer ponds, but a serious invasive weed where it can escape, and banned for sale in many regions.

Mature size: Individual rosettes 15-40 cm tall; colonies can blanket the entire surface of still water if unchecked.

How to tell eichhornia crassipes needs repotting

Repotting on a calendar is less reliable than reading the plant. For eichhornia crassipes, watch for these signs:

Roots spiralling thickly out of the drainage holes or pushing the whole plant up out of the pot.
The pot is so packed that water runs straight through in seconds and barely wets the soil.
It has split a plastic pot, or the rootball is a solid mass with almost no soil left when you slide it out.
Growth and (for eichhornia crassipes) flowering have clearly stalled despite good light and feeding — but remember this plant likes being snug, so a little crowding alone is not a reason to repot.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot eichhornia crassipes

Only every 2–4 years, when genuinely crowded. Eichhornia crassipes is one of the plants that genuinely prefers a snug pot — it grows and flowers better with its roots a little restricted, so resist the urge to repot it on schedule. Free-floating, clump-forming aquatic that reproduces by stolons to form dense interlocking rafts; rosettes of buoyant inflated leaves with trailing dark roots..

What size pot to step eichhornia crassipes up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Eichhornia crassipes positively prefers a snug pot: it flowers and grows better when the roots are a little restricted. The single biggest repotting mistake here is over-potting — dropping eichhornia crassipes into a pot two or three sizes up. All that surplus soil holds water the small root system cannot use, stays cold and wet, and rots the roots within weeks. When in doubt, choose the smaller pot.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot eichhornia crassipes

Early spring, just as new growth restarts, is the ideal window for eichhornia crassipes. The plant is moving into its strongest growth phase and re-roots into fresh soil quickly. Avoid repotting in winter dormancy or, for flowering plants, while it is in bud or bloom — recovery is slowest then and you risk dropping the flowers.

Step-by-step: repotting eichhornia crassipes

Confirm it actually needs it. Slide eichhornia crassipes out and check the roots. Only continue if it is genuinely packed — this plant prefers a snug pot, so if there is still soil and room, put it straight back.
Pick a pot only one size up. Choose a pot just 2–3 cm wider with good drainage. Resist anything bigger; over-potting is the main killer here.
Ease it out gently. Water lightly the day before, then tip eichhornia crassipes out, supporting the base. Tease the outer roots free only enough to stop them circling.
Repot at the same depth. Add a layer of fresh none — rootless floating plant, set the plant so the soil line sits exactly where it did before, and backfill around the sides, firming lightly.
Settle it in. Water once to settle the soil, then let it sit. Hold off on more water until the top of the soil dries — fresh soil around a small root system stays wet for a while.

Aftercare

Because the new soil holds more water than the old crammed rootball did, ease right back on watering — let the top of the soil dry before you water eichhornia crassipes again, or you will rot the roots in the very pot you just moved it to. Keep it out of harsh direct sun for a fortnight. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for eichhornia crassipes

Eichhornia crassipes wants none — rootless floating plant. Requires no soil or substrate. It draws nutrients directly from the water through its trailing roots, which also shelter fish and absorb excess nitrates, helping clear green water in summer. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting eichhornia crassipes — frequently asked questions

How often should you repot eichhornia crassipes?

Only every 2–4 years, when genuinely crowded for eichhornia crassipes. Only repot eichhornia crassipes every 2–4 years, and only when it is genuinely root-bound — it flowers and grows best slightly crowded. Step up just one pot size in spring using none — rootless floating plant. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does eichhornia crassipes need?

When is the best time of year to repot eichhornia crassipes?

Does eichhornia crassipes like to be root-bound?

Yes — eichhornia crassipes genuinely flowers and grows best when slightly pot-bound, so do not rush to repot it. The mistake to avoid is over-potting into a much larger pot: the excess soil stays wet, the roots cannot use it, and the plant rots. Only repot every few years and only one snug size up.

Should you fertilise eichhornia crassipes after repotting?

Not immediately. Wait about 4 weeks after repotting eichhornia crassipes. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.