Alternanthera cardinalis: red and easy plant for a natural aquarium
A red plant that adds contrast
Alternanthera cardinalis is one of the best plants for adding red tones and depth to a layout. The top of the leaves remains slightly greener, while the underside turns pink-red, creating highly visible shades and gradients in a bush.
Easy to grow successfully, it is suitable for low-tech tanks and can be propagated indefinitely from cuttings.
Why choose Alternanthera cardinalis?
- More intense red color under strong lighting; the contrast is immediate.
- Low-tech compatible: grows without CO2, and no fertilizer or technical substrate is required.
- Extremely easy propagation (cut tops and replant them, stem sections, horizontal layering).
- Background and midground: creates beautiful, dense, structural bushes.
- Hardy plant for beginners (simple substrate, very flexible parameters).
- Very valuable in aquascaping for creating focal points.
Growing tips (simple and effective)
- Lighting: medium to high (the stronger it is, the redder and more compact the plant will be).
- Substrate: simple sand is sufficient. When fish, shrimp, or other animals are present, no fertilizer is needed. The iron contained in their waste is also sufficient.
- CO2: completely unnecessary in a low-tech setup. In fact, fish or shrimp respiration provides enough.
- Parameters: soft to moderately hard water. A truly tolerant plant as long as the water is not extreme.
- Pruning: cut above a node and replant the top; the base will produce new shoots.
- Temperature: it does not survive winter outdoors. Aquarium plant, including in an unheated aquarium.
Use in aquascaping
- Strong contrasts with green plant groups. Nuanced, slightly metallic red.
- Place in the background to add depth, or in the midground so it stands out against a green background.
- Regular pruning creates a dense bush and a more compact shape. Remember to replant the cut sections!
Advantages in a low-tech aquarium
- Hardy, versatile, and adaptable (no technical substrate required).
- Red color without CO2 or added iron if the lighting is adequate.
- Easy propagation: affordable and quick maintenance.
FAQ - Alternanthera cardinalis
Is CO2 necessary to achieve a vivid red color?
No, but strong lighting enhances the color even further.
Can it live in a low-tech setup?
Yes. It grows well without CO2 as long as it receives enough light. The substrate is not very important to it.
How should I prune it to create a dense bush?
Cut and replant the tops. The base will resprout. Repeat to thicken the group.
Why is my Alternanthera turning green?
Usually insufficient lighting or a lack of iron (for example, when there are no fish): increase the light and add animals (fish, shrimp, microfauna). In rare cases, add an iron supplement.
Do goldfish eat it?
Some herbivorous fish may indeed nibble its delicate leaves: use caution in affected tanks.
Additional information
- Scientific name: Alternanthera cardinalis
- Plant type: red stem plant
- Lighting: medium to high; its red color is enhanced by light intensity.
- Temperature: 18 to 28°C. It does not tolerate cold; intended for aquariums, including unheated ones.
- Height: 30 to 50 cm in an aquarium (may grow above the water in an open tank).
- Packaging: 3 stems (indicative weight: 20 g).
- Guarantee: without rock wool or any artificial substrate of any kind.
- Recommendation: as a precaution, please never release this plant into the wild. It is not native to our regions and should obviously not become naturalized, but we must protect our ecosystems.
