Propagating Rotala sp. 'Yao Yai': Cuttings Guide

Propagate the robust large-form Thai cultivar Rotala 'Yao Yai' by cuttings, with topping steps, strong light, lean nitrate and CO2 to bring out its orange-red tones.

Overview

Rotala sp. 'Yao Yai' is a robust, large-form Thai locality cultivar of the Rotala rotundifolia group (family Lythraceae), with broader, slightly serrated leaves that take on rich orange-red tones under high light and CO2. The parent species is a common weed in rice paddies and wet places across India, China, Taiwan, Thailand, Laos and Vietnam, growing both submerged and emersed; the emersed form has rounded leaves, the submerged leaves are narrow and lanceolate, and under strong light leaves can become almost wine red.

Being a rotundifolia-group cultivar, 'Yao Yai' is propagated exactly like Rotala rotundifolia: by cuttings. Its larger, sturdier stems make handling and replanting easy.

Propagation Method (Cuttings)

Propagation is by cuttings. Removing the apical bud encourages lateral buds to develop along the stem at the internodes, so each topped stem branches and grows bushier. Replant the cut top as a new plant; the remaining base produces side shoots below the cut.

Step-by-Step

1. Pick a strong stem with well-colored tops, at least 12-15 cm tall.
2. Cut the top 5-10 cm with clean, sharp scissors.
3. Strip the lowest 2-3 cm of leaves so they do not rot under the substrate.
4. Plant the bare base firmly into nutrient-rich substrate, spacing for light penetration.
5. Leave the original base; it will push lateral shoots from internodes under the cut.
6. Maintain high light and CO2 so the replanted tops root quickly and color up orange-red.

Conditions for Healthy Growth

The parent species is undemanding but requires light to thrive; loss of lower leaves signals insufficient lighting. For 'Yao Yai' aim high: sufficient coloration begins around 80 umols of PAR, with the strongest color at 150-200 umols PAR. Like other rotundifolia forms it reddens under nitrate limitation: high nitrate keeps shoots green/yellow, moderate nitrate gives slightly orange/green shoots, and steep, prolonged nitrate limitation turns leaves dark red. Rotala can grow without CO2 but is much harder to keep healthy that way.

Trimming & Maintenance

Trim roughly every 10 days. Each topping removes the apical bud and triggers new lateral branching, multiplying the plant while keeping the stand dense. Replant the harvested tops to expand the group, and cut away old leggy bases that have lost their lower leaves.

Common Challenges

Bare lower stems and dropped leaves mean too little light. Thin, weakly branching stems indicate low CO2 or nutrients. If tops stay green rather than orange-red, nitrate is likely too high or light too weak. Note that the parent species is often confused with the closely related Rotala indica, which differs in inflorescence structure.