Featherfoil

Featherfoil runs on a European calendar, and that is the thing to plan around. It grows hard through cooler months, then slows or stalls when a tank sits warm for long stretches. In a tropical community held at 27 °C year-round it tends to thin out and disappoint; in an unheated or seasonally cool tank it does well.

The plant is one of the few genuinely aquatic members of the primrose family. Finely divided leaves grow densely in an alternate arrangement along the stem and give a soft, feathery outline that reads differently from broad-leaved stem plants around it. It reaches 30 cm or more, which puts it in the midground of a large tank or the background of a small one. In spring, established plants push flower spikes above the waterline carrying pale lilac blooms, which almost nothing else in an aquarium does.

Its range runs from western Europe into western Siberia, in nutrient-poor ponds, ditches and fens. Aim for 18 to 25 °C and pH 5 to 7.5, in soft to moderately hard water. It reacts badly to hard alkaline conditions. CO2 is optional and mainly buys denser growth. Propagation is by stem cuttings, trimmed and replanted. It is also winter-hardy outdoors across much of Europe and will flower reliably in a pond.