Alternanthera reineckii

Overview

Alternanthera reineckii — usually shortened to AR — is one of the most rewarding red-toned stem plants and a favourite for adding pink, red and violet into a green scape. Its broad, pointed leaves carry green-to-pink upper surfaces and rich reddish undersides, and several varieties (such as ‘Rosanervig’ and the compact ‘Mini’) exist. It is more forgiving than fine-leaved reds like Rotala H’ra and can even be grown low-tech, but like all red plants it shows its best colour under strong light with iron.

Planting & placement

AR is a stem plant. Plant the stems individually into the substrate with tweezers, a few centimetres apart, and in a group so the colour reads as a bold block. Its size and colour make it a natural midground or background feature, or a striking focal cluster. The compact ‘Mini’ form stays low enough for the foreground. See how to plant aquarium plants for planting depth and aquascaping for beginners for placing a colour accent.

Light, CO2 & ferts

Colour depends on light and iron. Medium-to-high light brings out the pink-red tones — our best light for a planted tank guide can help — while dim light keeps it greener. Injected CO2 is strongly recommended for fuller, faster, more reliably coloured growth. Dose a complete fertilizer with iron and potassium; our best plant fertilizer picks cover the micros AR needs to avoid pale, holey leaves.

Propagation & problems

Propagate by cuttings: snip a healthy top, strip the lowest leaves, and replant the cutting in the substrate, where it roots and grows on. The trimmed parent branches below the cut, so regular trimming builds a denser, bushier group. The common problems are green growth from too little light or iron, and small holes or stunted tips from nutrient or CO2 instability — a complete fertilizer and steady conditions fix both. Given good light, iron and ideally CO2, AR is one of the most beautiful reds you can grow.