Monte Carlo (Micranthemum tweediei) Care Guide
Micranthemum tweediei 'Monte Carlo' is a small-leaved carpeting plant from South America, easier to grow than HC Cuba but still benefits from CO2 and strong light.
Compiled by Aquairi from published sources · Published · Updated
Overview
Micranthemum tweediei, traded under the cultivar name 'Monte Carlo', is a small creeping plant in the family Linderniaceae. It forms a dense lawn of rounded leaves rarely above 5 cm tall and has become one of the most widely used carpet plants in aquascaping due to its tolerance of moderate light and its faster establishment compared with Hemianthus callitrichoides 'Cuba'.
Taxonomy
- Family: Linderniaceae
- Genus: Micranthemum
- Scientific name: Micranthemum tweediei
- Common cultivar: 'Monte Carlo'
- Trade synonym: New Large Pearl Grass
Habitat
The genus Micranthemum is native to the Americas, ranging from the eastern United States through tropical and subtropical South America. Monte Carlo grows along stream margins and seasonally flooded banks, where it spreads as a creeping mat that can survive both submerged and emersed conditions.
Tank requirements
- Temperature: 20-26 C (68-79 F)
- pH: 6.0-7.5
- GH: 3-10 dGH
- Lighting: medium to high (PAR ~50-80 at substrate)
- CO2: not strictly required but strongly recommended for compact carpet
- Substrate: nutrient-rich aquasoil
- Placement: foreground / carpet
Growth and propagation
Monte Carlo grows at a medium rate. Under CO2 injection and strong light, a carpet typically fills in within about 8 weeks. Propagation is performed by cuttings: trim runners every 10-14 days and replant the trimmings to thicken the lawn. Allowing the carpet to become too thick causes the lower layer to detach from the substrate.
Placement and aquascaping
Monte Carlo is used as a foreground carpet in nature-style and Iwagumi layouts. In low-tech tanks it tends to grow taller and more open; under high light and CO2 the leaves remain small and the lawn is tight. Trimming maintains shape and prevents floating clumps that occur when oxygen bubbles lift the mat.
Propagating Monte Carlo Mini (Micranthemum tweediei 'Mini')
Overview
Monte Carlo Mini is a smaller-leaved selection of the South American carpeting plant Micranthemum tweediei 'Monte Carlo'. It hugs the substrate even more tightly than the parent, making it a favourite foreground plant. It is propagated entirely by cuttings, specifically by dividing an existing mat into small replantable portions.
Propagation Method
The plant is propagated by splitting an established carpet. You separate a mat into small clumps or single strands, each carrying a little root, and replant them across the substrate. Smaller clumps and individual strands give a more even carpet because each piece roots in place and spreads outward rather than piling up.
Step-by-Step
- Lift or trim a section of the existing mat and tease it apart into small pieces, each with a bit of root attached.
- Plant the pieces in a grid, pushing each strand firmly into the substrate roughly every square inch.
- Make sure each strand is anchored flat so it grows along the substrate rather than upward.
- Keep light and CO2 high; a full carpet typically forms within two to three months as the pieces knit together.
Conditions for Healthy Growth
Monte Carlo spreads quickly with CO2 injection and higher light, around 100 micromoles of PAR, and success rates are very high once CO2 is in use, with roughly 50-60 micromoles sufficient in CO2-injected tanks. Strong, even light is what keeps the cultivar compact and pressed to the substrate rather than reaching upward.
Trimming & Maintenance
Maintain the carpet by trimming it low and removing old growth, cutting and picking off the older portions with scissors and tweezers so light reaches fresh shoots underneath. Every trimming yields more replantable pieces, so maintenance doubles as propagation. The plant is often grown emersed before sale, then transitions to its submersed carpet form in the aquarium.
Common Challenges
Loose clippings are hard to keep down in the substrate unless planted as bigger bunches, so anchor pieces firmly. If grown on a coir mat, the mat breaks down over time and it is better to remove the plants from it. Without enough light or CO2 the carpet thins, grows upward, and loses its tight, low habit.