Propagating Eleocharis acicularis (Dwarf Hairgrass): Spreading Runners into a Lawn

How to propagate dwarf hairgrass by dividing its runner-fed mat into small plugs and replanting them, with light, CO2 and substrate tips for a dense green lawn.

Overview

Eleocharis acicularis, the dwarf hairgrass or needle spikerush, is a grass-like plant with thin, sharply pointed stems that reach roughly 15 cm but stay much shorter in good carpeting conditions. It is sold commercially as an aquascaping plant and grows from a creeping rhizome, sending out runners and new leaves that eventually form a lush green lawn. It is widespread across Europe, Asia, North America and South America, growing naturally in marshes, vernal pools and shallow water.

Propagation Method (Runners)

Dwarf hairgrass propagates by runners that spread laterally across the substrate. The simplest way to multiply it is by division: the entire carpet can be lifted as one whole mat, the healthiest plants separated out, and those portions replanted across the planting area to start new runners.

Step-by-Step

Lift the carpet, or a section of it, as a single mat from the substrate.
Separate out the healthiest, greenest plants and divide them into small plugs.
Discard or trim away weak, browning, or algae-covered older growth.
Plant each plug into the substrate with tweezers, burying the roots firmly so the blades stand upright.
Space the plugs in a grid across the area so runners can connect them into a continuous lawn.
Allow the runners to spread; trim and replant excess as the carpet fills in.

Conditions for Healthy Growth

Dwarf hairgrass thrives with plenty of light and a high concentration of CO2, and needs at least moderate to strong lighting with CO2 injection for best carpeting results. It grows optimally in aquarium soil but adapts to fine gravel or sand if supplemented with liquid fertiliser.

Maintenance

Compared with other carpeting species, dwarf hairgrass is relatively low-maintenance and can grow for extended periods before needing trimming when conditions are adequate. Trim the runners occasionally to keep the lawn even, and replant trimmed portions elsewhere to expand the carpet.

Common Challenges

Thin or patchy carpets usually mean light or CO2 is too low for dense lateral spread.
Algae among the blades is best prevented by regular vacuuming of organic waste.
Weak establishment in inert gravel improves with aquarium soil or added liquid fertiliser.