Pearl Grass care guide
Pearl Grass (Micranthemum micranthemoides 'Pearl Grass') — high light, 22-28 °C, pH 5.5-7.5, CO2 recommended.
Compiled by Aquairi from published sources · Published · Updated
Overview
Pearl Grass (Micranthemum micranthemoides 'Pearl Grass') is an aquatic plant of the family Linderniaceae, listed in the Aquairi knowledge base as an intermediate-level species. It is typically grown under high light with pressurised CO2 injection on any substrate. Bushy stem plant with tiny round leaves resembling pearl grass. Easy to trim into low groundcover or let grow into a midground bush; thrives with CO2 and good light.
Taxonomy
- Family: Linderniaceae
- Genus: Micranthemum
- Scientific name: Micranthemum micranthemoides 'Pearl Grass'
- Common synonyms: Hemianthus 'Cuba' Pearl Grass
Habitat
Micranthemum is a genus of small creeping plants (Linderniaceae) of wet margins in the Americas; aquarium forms make low, fine-leaved carpets and foreground accents. In the Aquairi knowledge base, populations associated with this form are recorded from Cuba.
Growth requirements
- Lighting: high
- CO2: recommended
- Temperature: 22-28 °C (72-82 °F)
- pH: 5.5-7.5
- GH: 2-12 °dGH
- Substrate: aquasoil
- Maximum height: 15 cm
- Growth rate: fast
- Recommended placement: midground
Placement
A foreground carpet or low accent; bright light, CO2 and good flow keep the growth compact and pearling, while shade makes it leggy. In the Aquairi knowledge base this form is recommended for the midground under high light with pressurised CO2 injection, using undefined.
Propagation
Propagated by cuttings and by dividing the mat; portions re-attach to substrate or hardscape and continue to spread. Documented propagation techniques for this entry include: stem cuttings.
Common issues
Without strong light and CO2 the plant stretches and detaches, floating to the surface; trimming and firm planting keep the carpet intact.
Propagating Pearl Grass (Micranthemum) from Cuttings
Overview
Pearl Grass is a small Micranthemum plant in the family Linderniaceae, sold widely in aquascaping as 'pearlweed'. It is a low, subaquatic grower of roughly 5–20 cm with creeping stems, ascending branches and tiny opposite leaves only a few millimetres long. Trimmed low it becomes a bright-green groundcover; left taller it makes a soft midground bush.
Propagation Method (Cuttings)
Because the stems creep and branch, Pearl Grass is propagated simply by cutting and replanting the tops. Each cut top becomes a new plant, while the remaining base branches out, so repeated topping spreads it densely across the substrate.
Step-by-Step
- Select healthy, branching stems with bright tiny leaves.
- Cut the top 5–10 cm with sharp scissors.
- Strip the small leaves from the lowest 1–2 cm.
- Push the bare base into the substrate next to the parent.
- Repeat topping to widen the patch into a carpet.
Conditions for Healthy Growth
Pearl Grass thrives with strong light and CO2, which keep the tiny leaves close-set and the carpet low and dense; in weaker light it stretches upward and thins. Provide rich nutrients in soft, slightly acidic water to match its fast, hungry growth.
- Light: high, to keep the carpet low and compact.
- CO2: required for dense, bushy spread.
- Temperature: roughly 22–28 °C, soft to moderately hard water.
- Nutrients: high demand — dose water column and substrate.
Trimming & Maintenance
Trim roughly every two weeks once established. Frequent topping keeps the stand low and bushy and continuously yields cuttings to replant, so trimming and propagation go hand in hand. Replant the best tops and remove shaded lower growth to prevent the carpet lifting off the substrate.
Common Challenges
- Stretching and thinning under low light — raise light or CO2.
- Lower layers shading out and detaching as the carpet thickens.
- Slow spread if nutrients are lacking for this hungry grower.
- Confusion over the trade name, though care is the same regardless of species.