Propagating Rotala sp. 'Blood Red SG'

How to propagate the deep-red Rotala 'Blood Red SG' by cuttings and topping, plus the strong light and lean nitrate that bring out its intense blood-red color.

Overview

Rotala sp. 'Blood Red SG' is a deeply coloured selection within the Rotala rotundifolia group, a plant of the family Lythraceae native to Asia, including India, China, Taiwan, Thailand, Laos and Vietnam. The parent species shows narrow, lanceolate submerged leaves that, under strong light, can turn almost wine red. This Singapore selection pushes that colour further toward a dense blood red.

As a named cultivar of Rotala rotundifolia, 'Blood Red SG' is multiplied the same way as the parent species, by vegetative cuttings. Every replanted top is a clone that keeps the selection's intense colour.

Propagation Method (Cuttings)

Rotala rotundifolia propagates through cuttings, and the 'Blood Red SG' form is handled identically. Top the stem, replant the cut head, and leave the lower stump to branch into several new shoots. Because Rotala branches readily, a single replanted top quickly fills out into a dense red bush.

Step-by-Step

Select a strong, well-coloured stem with firm narrow leaves.
Cut the top 5-10 cm of the stem just above a node.
Strip the leaves from the lowest 2-3 cm to expose a clean planting section.
Plant the bare base into aquasoil, grouping several tops together for density.
Leave the trimmed stump in place so it branches into multiple new shoots.

Conditions for Healthy Growth

The parent species is described as undemanding but requires adequate light, and it tolerates relatively cool water. For this red selection, push light high and keep CO2 injected: leaf loss from the lower portions of the stem signals insufficient lighting. Strong light combined with lean nitrate and good iron drives the deepest red, since rich nitrogen tends to push these plants greener.

Trimming & Maintenance

Trim on a roughly two-week cadence to keep the stand compact and dense, replanting the colourful tops to expand the group. Light intensity influences both form and colour, so keep the canopy open enough that lower stems are not shaded into leaf loss. Grown emersed in shallow water the plant develops rounded leaves and pale pink flowers, but the prized blood-red, narrow-leaf form is the submersed one.

Common Challenges

Lower-stem leaf loss caused by insufficient light or self-shading.
Color fading toward green when nitrate is too high or light too weak.
Reversion to rounded leaves if a stem grows emersed above the waterline.
Slow color-up on freshly replanted tops until they root and adapt.