Overview & Origin
Alternanthera reineckii is native to South America, growing in marshy, seasonally flooded areas in Brazil, Paraguay, and Argentina. It belongs to the family Amaranthaceae (the amaranth family) and is one of the few truly red aquarium plants that maintains intense coloration under proper conditions.
The species has been cultivated into several aquarium varieties, with 'Mini' being by far the most popular due to its compact growth habit that works perfectly as a midground accent plant in aquascapes.
How to Plant
- Plant stems 1.5–2 inches deep in nutrient-rich substrate. Space 1–2 inches apart.
- The 'Mini' variety stays compact (2–4 inches) and is ideal for midground placement between foreground carpets and taller background plants.
- Standard AR grows taller (6–12 inches) and works as a background accent.
- Plant in groups of 3–5+ for visual impact — isolated single stems look sparse.
Water Parameters
- Temperature: 72–82°F (22–28°C)
- pH: 6.0–7.5
- KH: 1–6 dKH
- GH: 2–8 dGH
AR prefers soft, slightly acidic water. In hard, alkaline water, growth slows and colors may be less vibrant.
Maximizing Red Coloration
AR's vivid color is its main attraction. To get the deepest reds:
- High light: Essential — 50+ PAR at the plant. Under low light, AR turns brownish-green and loses its appeal.
- Iron supplementation: Critical for red pigment production. Dose iron-rich fertilizer 3x per week.
- CO2 injection: Not strictly required but strongly recommended. CO2 produces the most vivid, saturated reds and prevents the plant from becoming leggy and pale.
- Nitrate balance: Moderate nitrate (10–20 ppm). Too much nitrogen can shift colors toward brown; too little causes poor growth.
Popular Varieties
- Alternanthera reineckii 'Mini': The most popular variety. Compact, stays low (2–4 inches), intense red/pink coloration. Perfect for midground accents in aquascapes.
- Alternanthera reineckii 'Rosanervig': Distinctive pink veins on green-to-red leaves. Less vivid overall red but unique patterning.
- Alternanthera reineckii 'Rosaefolia': Larger leaves with broader growth. Deep red undersides.
- Alternanthera reineckii 'Variegated': Green and pink/white variegation. Rare and striking.
Common Problems & Solutions
- Losing red color / turning green: Insufficient light is the #1 cause. Increase to 50+ PAR and supplement iron.
- Melting after planting: Common, especially with tissue culture. The emersed leaves melt and are replaced by submersed growth in 2–3 weeks. Be patient.
- Leggy/stretched growth: Not enough light. AR gets tall and sparse when light-starved. Increase light intensity.
- Dropping lower leaves: Normal as the plant matures — lower portions receive less light. Trim tops and replant, discarding bare stems.
- Slow growth: AR is naturally a moderate grower. CO2 and good nutrition speed things up, but don't expect Rotala-like growth rates.
Frequently Asked Questions
Can AR Mini grow without CO2?
Yes, but with compromises — slower growth, less compact form, and less vivid coloration. For the signature look seen in aquascaping competitions, CO2 is strongly recommended.
Is AR a beginner plant?
It's a step up from beginner. Not as forgiving as Ludwigia Repens or Rotala, but manageable for anyone willing to provide good light and basic fertilization.
How do I keep AR Mini compact?
High light keeps it short and bushy. Regular trimming of the tops encourages side shoot growth. Low light causes it to stretch upward.