Propagating Alternanthera reineckii 'Cardinalis'

How to propagate the red stem plant Alternanthera reineckii 'Cardinalis' by topping and replanting cuttings, with strong light, CO2 and iron for deep red leaves.

Overview

Alternanthera reineckii 'Cardinalis' is a red, broad-leaved freshwater stem cultivar of A. reineckii, a species native to South America that grows up to about 30 cm tall in submerged and semi-aquatic habitats. This selection carries pink- to red-coloured leaves that deepen to richer reds and even purple tints under strong light, making it a striking mid-foreground accent.

Propagation Method

Like other stem plants, this Alternanthera is propagated by stem cuttings, also called topping. Once a stem grows tall enough you simply prune off the top portion and replant it; the cutting roots into the substrate while the trimmed parent branches out below, so a single plant steadily becomes a dense group.

Step-by-Step

Let a healthy stem grow tall enough to top.
Cut the top several centimetres of the stem with clean scissors.
Strip the lowest leaves from the cutting to leave a clean planting node.
Push the cutting into nutrient-rich substrate a few centimetres deep.
Replant cuttings in small groups so the bed fills in evenly.

Conditions for Healthy Growth

For the best colour, grow 'Cardinalis' as a high-tech plant: strong lighting, pressurised CO2 and a complete fertiliser drive vigorous growth, and high light in particular brings out the deepest reds and purple tints. Supplementing iron supports the intense red pigmentation typical of red Alternantheras. Keep it in soft to moderately hard freshwater within a comfortable tropical temperature range.

Maintenance

Trim and replant tops regularly to keep the group compact and to multiply your stock at the same time. Routine topping both controls height and provides fresh cuttings, while steady fertilisation and CO2 keep the new shoots colouring up well.

Common Challenges

Weak colour and leggy, sparse growth almost always trace back to too little light, missing CO2 or insufficient iron and nutrients. Because it is demanding for best results, dial in those three factors together rather than one at a time, and remove any melted or decaying lower leaves promptly.