Alternanthera reineckii is the red plant most planted tanks end up with. Tropica sells it as three cultivars rather than the plain species, and rates all of them medium for light, CO2 and difficulty. The colour is the point, and the colour is what the conditions decide.
Three cultivars, three sizes
Tropica lists no plain Alternanthera reineckii. Which one you buy changes how big it gets and where it belongs in the tank.
| Cultivar | Height (Tropica) | What Tropica says |
|---|---|---|
| ‘Mini’ | 5 to 10+ cm | Compact, slower growing, for small tanks or the foreground of a larger scape |
| ‘Pink’ | 20 to 30+ cm, stems 25 to 50 cm | Pink leaf undersides, strongest planted in groups |
| ‘Rosanervig’ | 5 to 20+ cm | Vibrant pink leaves with light nerves, compact, for the mid-section or the front when cut well |
What it needs
| Requirement | Alternanthera reineckii |
|---|---|
| Light demand | Medium |
| CO2 demand | Medium |
| Difficulty | Medium |
| Growth rate | Medium |
| Placement | Stem, midground |
This is the first plant in this batch that asks for something. Tropica’s line on the genus is that good light and fertiliser conditions, as well as CO2 additive, are material for growth and colour development. For ‘Mini’ they say high light intensity and the addition of CO2 improves the plant’s growth and overall appearance.
Getting the colour
For ‘Pink’, Tropica says good light encourages the leaves to turn red, and that the pink undersides give an effective contrast to the green plants around them, particularly in groups. One stem on its own is wasted. A block of it against green is what people are copying when they build a Dutch layout.
Propagating it
Tropica’s method for ‘Pink’ is to nip off the terminal bud and plant it in the substrate. That also makes the mother plant bushier, because more side shoots form. It is the same trim and replant cycle as Rotala, and it is how one pot becomes a group.
Alternanthera reineckii questions
Does Alternanthera reineckii need CO2?
Tropica rates its CO2 demand as medium and says CO2 addition is material for growth and colour development. It will grow without, but this is not a plant that shows its best in a tank with no added carbon.
Which Alternanthera reineckii suits a small tank?
‘Mini’. Tropica gives it a height of 5 to 10+ cm and describes it as compact and slower growing, suitable for small aquariums or as a foreground plant in larger aquascapes.
How do you get Alternanthera reineckii to turn red?
Light, first. Tropica says good light encourages the leaves of ‘Pink’ to turn red, and adds that good light and fertiliser, together with added CO2, are material for colour development across the genus.
Sources: Tropica, Alternanthera reineckii ‘Pink’; Tropica, Alternanthera reineckii ‘Mini’; Tropica, Alternanthera reineckii ‘Rosanervig’.