Alternanthera reineckii
Alternanthera reineckii
Also known asScarlet temple · Alternanthera reineckii 'Roseafolia' · AR Mini (dwarf cultivar)
Water parameters
Light and nutrients
Substrate type: nutrient rich. Propagation: stem cuttings.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
| Dirted tank (mineralized topsoil) (DIY soil substrate) | slightly acidic | very high |
With fish
Origin and habitat
Native to subtropical and tropical South America, recorded from Argentina, Bolivia, Brazil, Paraguay and Uruguay, with the type locality at Porto Alegre in Rio Grande do Sul, Brazil. A member of the amaranth family, Amaranthaceae, it grows along riverbanks and in seasonally flooded ground, mostly emersed, and is one of the few Alternanthera species that also grow fully submersed, which is what makes it valuable in aquascaping. The emersed form is green with reddish undersides; submersed and under strong light it develops the deep red, pink or magenta leaves and stems it is prized for. Several aquarium cultivars circulate, including the standard 'Roseafolia', the pink-veined 'Rosanervig', and a compact dwarf, AR Mini. Stems are pubescent, with oval leaves roughly 3.5 cm long; aquarium height for the taller forms reaches around 40 to 50 cm.
Care notes
One of the few dependably red aquarium plants that does not strictly need carbon dioxide injection, though it colours far more vividly with CO2 and strong light; without CO2 expect brownish-red to burgundy rather than bright crimson. Light is the main lever: bright lighting, above roughly 40 PAR at the substrate, brings out the red and prevents the lower leaves from dropping and the stem going leggy, while deep shade behind taller plants ruins the colour. Iron is the other key, because the red pigment fades to pale pink or green without enough of it, so dose iron and micronutrients in the water column and use a nutrient-rich substrate or root tabs for this moderate root feeder. Growth is moderate, faster with CO2 (the standard form can put on 10 to 15 cm a month), so trim and replant the tops every few weeks to keep growth bushy. Propagate by cuttings: snip the top 10–15 cm just above a node and replant straight into the substrate, and the cut stem usually throws side shoots. It is an ornamental submersed plant rather than a crop, so it is not suited to media-bed aquaponics or hydroponics.