Repotting guide

When & how to repot Nardoo (Marsilea mutica)

Also called Nardoo, Banded Nardoo, Australian Water Clover, Four-leaf Water Clover.

More about nardoo

About Nardoo

Marsilea mutica · also called Nardoo, Banded Nardoo · houseplant

Marsilea mutica is an ornamental Australian aquatic fern whose floating leaves closely resemble a four-leaf clover with distinctive pale green central marbling on dark green leaflets. Native to Australia and New Caledonia, it grows at the margins of ponds, streams, and slow-moving water, spreading by vigorous rhizomes. It is best grown in a submerged lattice basket to contain its spread. The ASPCA confirms closely related Marsilea species as non-toxic to cats and dogs.

Mature size: Individual leaves 2–3 cm across; established clumps spread 1–1.5 m in a season if uncontained; height above water surface 5–15 cm.

Watch for — Invasive spread: Marsilea mutica spreads aggressively by rhizomes and can rapidly take over a small pond or escape into nearby waterways — always grow in a submerged lattice basket and thin the root mass weekly during the growing season.

How to tell nardoo needs repotting

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

Every 12–18 months — sooner if roots show fast. Nardoo's growth habit — vigorous, spreading aquatic with floating four-lobed leaves on long stalks rising from a fast-spreading rhizome at the pond floor. — sets the pace. Marsilea mutica is an ornamental Australian aquatic fern whose floating leaves closely resemble a four-leaf clover with distinctive pale green central marbling on dark green leaflets. Native to Australia and New Caledonia, it grows at the margins of ponds, streams, and slow-moving water, spreading by vigorous rhizomes. It is best grown in a submerged lattice basket to contain its spread. The ASPCA confirms closely related Marsilea species as non-toxic to cats and dogs.

What size pot to step nardoo up to

Step up one pot size — about 2–3 cm (an inch) wider. Nardoo 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 nardoo

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

Time it for spring. Repot nardoo 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 nardoo out and gently loosen any roots circling the bottom of the rootball.
Repot at the same depth. Put a layer of fresh heavy loam or aquatic pond compost in a submerged lattice basket 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 nardoo 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 nardoo

Nardoo wants heavy loam or aquatic pond compost in a submerged lattice basket. Use a heavy, loamy aquatic compost without added fertiliser pellets; excess nutrients will cause algal bloom. Top-dress with a 1–2 cm layer of fine gravel to prevent the soil from dispersing into the water. Divide the root mass and replant in fresh substrate every 2–3 years. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting nardoo — frequently asked questions

How often should you repot nardoo?

Every 12–18 months — sooner if roots show fast for nardoo. Repot nardoo 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 heavy loam or aquatic pond compost in a submerged lattice basket. Don't jump several sizes — that soggy excess soil is what rots vigorous roots.

What size pot does nardoo need?

When is the best time of year to repot nardoo?

Can you put nardoo straight into a much bigger pot?

No. Even a fast-growing nardoo 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 nardoo after repotting?

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