Alternanthera reineckii

Overview

Alternanthera reineckii is one of the go-to red plants for creating a focal point in an aquarium. Its lance-shaped leaves range from pink to wine red, often with deep purple undersides, and contrast beautifully with surrounding greens. It is native to South America (Brazil, Paraguay, Argentina), where it grows in marshy areas.

Several forms are sold: 'Rosaefolia', the most forgiving, with pinkish leaves; 'Cardinalis', large and very red; and 'Mini' (often sold as AR Mini), compact and ideal for the front of small tanks but more demanding. It is not a hard plant, but its color depends directly on light and fertilization: in a dim tank it survives, yet loses most of its appeal.

Care and tank setup

Place it in the midground, as a group that stands out against green plants and gets full light.

• Light: medium-high to high. This is the key to color: in low light it turns brownish green and sheds leaves.
• CO2: optional for 'Rosaefolia', strongly recommended for 'Mini' and for deep red tones.
• Substrate: an aquasoil or root tabs; it develops solid roots and uses nutrients from the substrate.
• Planting: single stems, about an inch apart, with the lower leaves stripped.

It dislikes sudden changes: losing a few leaves while it settles in after planting is normal. Avoid shading it with floaters and watch for algae on its slow-growing leaves. Some herbivorous fish will nibble it.

Fertilizing and trimming

Iron is essential for color: use a complete fertilizer with micronutrients and, if possible, an iron supplement. Keeping nitrate moderate brings out the reds, but avoid outright deficiency. Trim by pinching off the tops: it branches out into dense clumps. Remove damaged lower leaves and replant the tops when the base gets bare.

Propagation

It propagates from cuttings: snip 3-4 inch tops with several nodes, strip the lower leaves and plant them in a nutrient-rich substrate. Trimmed stems also sprout side shoots. Rooting may be slow in low light. Dispose of trimmings in the trash or compost, never in streams or wetlands: several species in this genus are invasive.

Recommended equipment

What you need to keep the Alternanthera reineckii healthy, checked against Amazon stock.