Alternanthera cardinalis: red and easy plant for natural aquarium
A red plant that brings contrast
Alternanthera cardinalis is one of the best plants to bring red and depth to a decor. The top of the leaves remains a bit greener, while the underside turns pink-red, creating very visible shades and gradients in a bush.
Easy to succeed, suitable for low-tech tanks and can be propagated endlessly.
Why choose Alternanthera cardinalis?
- More intense red color under strong light, the contrast is immediate.
- Low-tech compatible: grows without CO2 and no fertilizer or technical soil is necessary.
- Ultra-simple cuttings (cut and replanted tips, sections, horizontal layering).
- Background and middle: creates superb dense and structuring bushes.
- Robust plant for beginners (simple soil, very flexible parameters).
- Very valuable in aquascaping to create focal points.
Cultivation tips (simple and effective)
- Light: medium to strong (the stronger, the redder and more compact it is).
- Substrate: simple sand is enough. In the presence of fish, shrimp, or other animals, no fertilizer needed. The iron contained in their waste is also sufficient.
- CO2: totally unnecessary in low-tech. In fact, the respiration of fish or shrimp provides enough.
- Parameters: fresh to moderately hard water. Really tolerant plant if the water is not extreme.
- Size: cut above a node and replant the tip; the base will emit new shoots.
- Temperature: does not survive winter outdoors. Aquarium plant, even unheated.
Use in aquascaping
- Strong contrasts with green masses. Nuanced red, slightly metallic.
- Background placement to give depth, or in the middle to stand out against a green background.
- Regular size for a dense bush and a stockier silhouette. Remember to replant the cut parts!
Advantages in low-tech aquariums
- Resistant, versatile, and adaptable (no technical substrate required).
- Red color without CO2 or iron addition if lighting is adequate.
- Easy propagation: economical and quick maintenance.
FAQ - Alternanthera cardinalis
Is CO2 needed to get bright red?
No, but strong light further enhances the color.
Can it live in low-tech?
Yes. It grows well without CO2, provided there is enough light. The substrate does not matter much.
How to trim it for a dense bush?
Cut and replant the tops. The base will sprout. Repeat to thicken the cluster.
Why is my Alternanthera turning green?
Often insufficient lighting or lack of iron (in the absence of fish for example): increase light and introduce animals (fish, shrimp, micro-fauna). In rare cases, add an iron supplement.
Do goldfish eat it?
Some herbivorous fish can indeed nibble on its thin leaves: caution in affected tanks.
Additional information
- Scientific name: Alternanthera cardinalis
- Plant type: red stem plant
- Light: medium to strong, its red color being favored by light intensity.
- Temperature: 18 to 28°C. It does not tolerate cold: reserved for the aquarium, even unheated.
- Size: 30 to 50 cm in aquarium (can emerge in open tanks).
- Packaging: 3 stems (indicative weight: 20 g).
- Guarantee: without rock wool or any artificial substrate of any kind.
- Recommendation: as a precautionary principle, please never release this plant into the wild. It is not native to our regions, should obviously not naturalize, but we must preserve our ecosystems.
