Repotting guide

When & how to repot Hemianthus micranthemoides (Hemianthus micranthemoides)

Also called pearl weed, pearlwort.

More about hemianthus micranthemoides

About Hemianthus micranthemoides

Hemianthus micranthemoides · also called pearl weed, pearlwort · tropical

Hemianthus micranthemoides, pearl weed, is a versatile small-leaved stem plant for freshwater aquascapes. Slender stems carry whorls of tiny bright-green leaves and can be grown tall as a bushy midground, trimmed low as a carpet, or left to trail. It is far easier than dwarf baby tears, growing well in moderate light and pearling vigorously when CO2 is supplied.

Mature size: Stems reach 10-25 cm tall before trimming; as a carpet it stays a few centimetres high and spreads to fill the foreground.

Watch for — Leggy growth in low light: Weak light makes stems stretch with sparse leaves. Increase intensity and trim often to promote compact, branching, carpet-forming growth.

How to tell hemianthus micranthemoides needs repotting

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

Every 12–18 months — sooner if roots show fast. Hemianthus micranthemoides's growth habit — fast-growing small-leaved stem plant with fine branching stems; grows upright and bushy or, when trimmed and bright-lit, creeps into a low carpet. — sets the pace. Hemianthus micranthemoides, pearl weed, is a versatile small-leaved stem plant for freshwater aquascapes. Slender stems carry whorls of tiny bright-green leaves and can be grown tall as a bushy midground, trimmed low as a carpet, or left to trail. It is far easier than dwarf baby tears, growing well in moderate light and pearling vigorously when CO2 is supplied.

What size pot to step hemianthus micranthemoides up to

Step up one pot size — about 2–3 cm (an inch) wider. Hemianthus micranthemoides 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 hemianthus micranthemoides

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

Time it for spring. Repot hemianthus micranthemoides 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 hemianthus micranthemoides out and gently loosen any roots circling the bottom of the rootball.
Repot at the same depth. Put a layer of fresh fine aquarium substrate or aquasoil 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 hemianthus micranthemoides 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 hemianthus micranthemoides

Hemianthus micranthemoides wants fine aquarium substrate or aquasoil. Plant stems into fine gravel or nutrient-rich aquasoil; roots are fine but effective. Rich substrate plus water-column feeding produces the densest growth, whether grown upright or as a carpet. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting hemianthus micranthemoides — frequently asked questions

How often should you repot hemianthus micranthemoides?

Every 12–18 months — sooner if roots show fast for hemianthus micranthemoides. Repot hemianthus micranthemoides 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 fine aquarium substrate or aquasoil. Don't jump several sizes — that soggy excess soil is what rots vigorous roots.

What size pot does hemianthus micranthemoides need?

When is the best time of year to repot hemianthus micranthemoides?

Can you put hemianthus micranthemoides straight into a much bigger pot?

No. Even a fast-growing hemianthus micranthemoides 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 hemianthus micranthemoides after repotting?

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