Propagating Eleocharis parvula (Dwarf Hairgrass)

How to propagate dwarf hairgrass by splitting its runner-grown mat into small plugs and replanting them to fill a fine, lawn-like carpet under good light and CO2.

Overview

Eleocharis parvula is a small spikesedge in the family Cyperaceae, a perennial herb that grows tufts of spongy, compressible stems usually no more than about 10 centimetres tall. In the aquarium it is known as dwarf hairgrass and is used as a foreground carpet plant. It spreads horizontally by runners, so a few small portions can gradually knit together into a fine, lawn-like turf.

Propagation Method

Dwarf hairgrass is propagated vegetatively by its runners. Rather than cutting tops, you divide an existing mat into small plugs and replant them spaced across the substrate. Most carpets spread fairly quickly by runners when conditions are good, so each plug sends out new shoots and fills the gaps between them.

Step-by-Step

Lift a healthy section of the existing mat or a fresh pot, rinsing soil from the roots.
Split it into small tufts of roughly 2–4 cm, keeping roots attached to each tuft.
Plant each tuft into rich aquasoil, spacing them a few centimetres apart so runners can fill the gaps.
Push the roots in deep enough that the tufts stay anchored against water flow.
Maintain good light and stable CO2 so the new plugs begin sending out runners quickly.

Conditions for Healthy Growth

For a dense carpet, aim for roughly 40–50 PAR of light together with CO2 injection (around 20 ppm or more); without CO2, far more light is needed. With good CO2 the plant can divert energy from carbon capture into vegetative growth and will spread with as little as 20+ PAR. A rich aquasoil supports the runner-driven spread.

Maintenance

Once established, trim and uproot sections periodically to keep the carpet low, thin and tidy and to prevent debris and algae building up in the dense growth. Removing thinned-out portions also gives you ready-made plugs for replanting elsewhere.

Common Challenges

Slow or patchy carpeting, usually caused by too little light or unstable CO2.
Algae taking hold in dense or neglected growth that has not been thinned.
Tufts floating up before they root if planted too shallowly or in loose substrate.