Java Fern

Scientific name: Microsorum pteropus

Origin: South-East Asia

Growth: slow

Light and CO2: low; no CO2 needed

Placement: attach to wood or rock; rhizome exposed

Propagation: plantlets on the leaves; rhizome division

Java Fern (Microsorum pteropus) is one of the few plants that genuinely tolerates neglect. It is a true fern from South-East Asia with long, leathery green fronds, and it grows slowly in low light without added CO2 or special substrate. It adapts to soft acidic water and to hard alkaline water alike. Its rhizome, the dark horizontal stem the leaves and roots grow from, must not be buried; covered, it rots. Tie or glue it to wood or rock and the roots will grip on by themselves. Very bright light can scorch or melt the fronds, and because it grows slowly, algae can settle on old leaves under strong lighting, so a shaded spot works well. Small plantlets appear along the edges and tips of older leaves, and a stressed plant may make dozens on a single leaf; they drop off and float until they catch somewhere, or you can pinch them off and tie them where you want them. The tough fronds are ignored by most plant-eating fish and give shrimp a broad surface to graze biofilm, the microbial film they feed on.

Water: tolerant of a wide range of hardness and pH and ordinary tropical temperatures.

Planting: attach the rhizome to wood or rock with cotton thread or aquarium-safe cyanoacrylate gel glue, or wedge it into a gap. It can also float. If set on the substrate, keep the rhizome fully above it. Cut the rhizome into pieces with a few leaves each to propagate, or grow on the leaf plantlets.

Light and feeding: low to medium light; avoid very strong light. CO2 injection (carbon dioxide gas added to boost growth) is not needed. A light liquid fertiliser dose is enough.