Repotting guide

When & how to repot Riccia fluitans (Riccia fluitans)

Also called crystalwort, floating liverwort.

More about riccia fluitans

About Riccia fluitans

Riccia fluitans · also called crystalwort, floating liverwort · tropical

Riccia fluitans, crystalwort, is a rootless aquatic liverwort that naturally floats as a bright green tangled mat. Famously pinned down with mesh in aquascaping, it forms a dazzling pearling carpet under strong light and CO2. Vivid but demanding, it sheds oxygen bubbles when thriving and needs high light, injected CO2 and frequent trimming to stay anchored.

Mature size: Mats grow several centimeters thick and spread quickly across the surface or pinned area, needing frequent trimming.

Watch for — Floating free: Being rootless, it constantly tries to detach and rise; secure it under mesh or fine netting and re-pin escaping clumps to keep the carpet intact.

How to tell riccia fluitans needs repotting

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

Roots poking out of the drainage holes or coiling visibly around the inside of the pot.
You are watering far more often than you used to because the rootball dries out within a day or two.
Water runs straight through and out the bottom without soaking in.
Top growth has slowed or new riccia fluitans leaves are noticeably smaller than older ones despite good light.

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 riccia fluitans

Every 12–18 months — sooner if roots show fast. Riccia fluitans's growth habit — rootless, fast-growing and buoyant; branching forked fronds form a tangled mat that floats unless physically pinned down. — sets the pace. Riccia fluitans, crystalwort, is a rootless aquatic liverwort that naturally floats as a bright green tangled mat. Famously pinned down with mesh in aquascaping, it forms a dazzling pearling carpet under strong light and CO2. Vivid but demanding, it sheds oxygen bubbles when thriving and needs high light, injected CO2 and frequent trimming to stay anchored.

What size pot to step riccia fluitans up to

Step up one pot size — about 2–3 cm (an inch) wider. Riccia fluitans grows fast, so it will fill that space within a season, but jumping several sizes at once still backfires: the unused soil stays soggy and rots even a vigorous root system. One size at a time, every year or so, is the rhythm.

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 riccia fluitans

Early spring, just as new growth restarts, is the ideal window for riccia fluitans. 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 riccia fluitans

Time it for spring. Repot riccia fluitans in early spring as growth restarts so it re-roots quickly into the fresh soil.
Choose one size up. Pick a pot about 2–3 cm wider with drainage holes. One step only — a much bigger pot stays soggy and rots roots.
Ease the plant out. Water lightly the day before, then tip riccia fluitans out and gently loosen any roots circling the bottom of the rootball.
Repot at the same depth. Put a layer of fresh none — floats or is pinned to hardscape in the new pot, set the plant so its soil line is unchanged, and backfill, firming lightly.
Water and pause feeding. Water once to settle the soil. Hold off fertiliser for about a month — fresh mix already has nutrients and feeding now burns new roots.

Aftercare

Water riccia fluitans once to settle the soil, then let the surface dry before watering again — fresh mix around the roots stays wetter than the old compacted ball, so the commonest post-repot mistake is overwatering. Keep it out of direct sun for a week or two while roots re-establish. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for riccia fluitans

Riccia fluitans wants none — floats or is pinned to hardscape. Rootless with no anchoring rhizoids; it must be trapped under mesh or netting against wood or stone to form a submerged carpet, otherwise it floats free at the surface. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting riccia fluitans — frequently asked questions

How often should you repot riccia fluitans?

Every 12–18 months — sooner if roots show fast for riccia fluitans. Repot riccia fluitans roughly every 12–18 months, in early spring as growth restarts. It grows fast and circles its pot quickly, so step up one size (about 2–3 cm wider) into fresh none — floats or is pinned to hardscape. Don't jump several sizes — that soggy excess soil is what rots vigorous roots.

What size pot does riccia fluitans need?

When is the best time of year to repot riccia fluitans?

Can you put riccia fluitans straight into a much bigger pot?

No. Even a fast-growing riccia fluitans should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise riccia fluitans after repotting?

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