Repotting guide

When & how to repot Monosolenium tenerum (Monosolenium tenerum)

Also called pellia, false pellia.

More about monosolenium tenerum

About Monosolenium tenerum

Monosolenium tenerum · also called pellia, false pellia · tropical

Monosolenium tenerum, sold as pellia, is a thick, brittle thalloid liverwort grown fully submerged in freshwater aquariums. It forms dense, branching cushions of dark green crystalline foliage. Unrooted, it must be tied to rock or wood until it anchors. Brighter than most mosses, it grows fast in nutrient-rich, CO2-supplemented tanks but breaks apart easily.

Mature size: Cushions 5-10 cm tall and spreading indefinitely; individual thalli a few millimetres wide. Regular trimming keeps the mound tidy.

Watch for — Falls apart / drifts: Has no true roots and is very brittle, so clumps disintegrate when handled. Tie to hardscape with thread or fine netting until rhizoids anchor it.

How to tell monosolenium tenerum needs repotting

Repotting on a calendar is less reliable than reading the plant. For monosolenium tenerum, 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 monosolenium tenerum 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 monosolenium tenerum

Every 12–18 months — sooner if roots show fast. Monosolenium tenerum's growth habit — fast-growing, mat-forming thalloid liverwort with flattened, repeatedly forking dark-green branches that build a springy three-dimensional cushion. — sets the pace. Monosolenium tenerum, sold as pellia, is a thick, brittle thalloid liverwort grown fully submerged in freshwater aquariums. It forms dense, branching cushions of dark green crystalline foliage. Unrooted, it must be tied to rock or wood until it anchors. Brighter than most mosses, it grows fast in nutrient-rich, CO2-supplemented tanks but breaks apart easily.

What size pot to step monosolenium tenerum up to

Step up one pot size — about 2–3 cm (an inch) wider. Monosolenium tenerum 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 monosolenium tenerum

Early spring, just as new growth restarts, is the ideal window for monosolenium tenerum. 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 monosolenium tenerum

Time it for spring. Repot monosolenium tenerum 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 monosolenium tenerum out and gently loosen any roots circling the bottom of the rootball.
Repot at the same depth. Put a layer of fresh no substrate — epiphytic on 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 monosolenium tenerum 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 monosolenium tenerum

Monosolenium tenerum wants no substrate — epiphytic on hardscape. Not rooted in soil. Tie or net the brittle clump onto stone, lava rock or driftwood; it grips by rhizoids over a few weeks. Loose fragments simply drift and re-establish wherever they settle. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting monosolenium tenerum — frequently asked questions

How often should you repot monosolenium tenerum?

Every 12–18 months — sooner if roots show fast for monosolenium tenerum. Repot monosolenium tenerum 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 no substrate — epiphytic on hardscape. Don't jump several sizes — that soggy excess soil is what rots vigorous roots.

What size pot does monosolenium tenerum need?

When is the best time of year to repot monosolenium tenerum?

Can you put monosolenium tenerum straight into a much bigger pot?

No. Even a fast-growing monosolenium tenerum 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 monosolenium tenerum after repotting?

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