Dwarf hairgrass

Overview

Dwarf hairgrass (Eleocharis parvula) is the classic grassy carpet — fine, bright-green blades that spread across the foreground like a mown lawn and sway gently in the flow. It is a beautiful effect, but a demanding one: like all carpeting plants, dwarf hairgrass needs high light and CO2 to stay short and dense. Under weak light it grows tall and sparse, so plan the tank around its needs.

Planting & placement

Divide the mat into small clumps of a few blades each and plant them spaced a couple of centimetres apart in a nutrient substrate across the foreground. Spacing lets the runners fill the gaps and gives faster, more even coverage than planting one dense block. Trim the blades short right after planting to encourage runners. The dry-start method works well too. See how to plant aquarium plants for the clump technique.

Light, CO2 & ferts

Dwarf hairgrass is a high-tech carpet. It needs strong light reaching the substrate and, for a proper dense lawn, CO2 — without it the grass stretches tall and thin. Feed a full liquid fertilizer routine, since a growing carpet is hungry. Our best light for a planted tank and best CO2 system guides cover suitable gear.

Propagation & problems

Dwarf hairgrass spreads entirely by runners — horizontal shoots that pop up new blades and knit the carpet together. To propagate or fill gaps, lift a section, split it and replant. Trimming the tops with scissors triggers denser runner growth. The main problems are tall, leggy growth (add light and CO2) and post-planting melt as emersed grass converts to submersed form (normal — trim and wait). For a rounder-leaved lawn, compare it with Monte Carlo, or with the far easier, no-CO2 dwarf sagittaria if a high-tech setup isn’t for you. Watch for detritus settling into the dense blades over time; gentle flow across the carpet and light substrate vacuuming keep it clean. Once established, a hairgrass lawn is one of the most striking effects in the hobby.