Giant hairgrass

Eleocharis montevidensis

Also known as Sand spikerush, Tall hairgrass, Montevideo spikerush, Eleocharis sp. 'Montevidensis'

FreshwaterRhizomeRunnersDivision

Care at a glance

Light: Medium light
CO2: CO₂ beneficial
Temperature: 64–82°F; 18–28°C
Max height: 11.8 in; 30 cm

Growth rate: Medium
Placement: Background
Type: Rhizome
pH: 6.0–7.5
Hardness: 2–15 dGH
Spread: 5.9 in (15 cm)
Nutrient uptake: Root feeder
Growth region: Submersed or emersed
Difficulty: Easy
Family: Cyperaceae
Origin: A spikerush from the Americas that grows in wet sand, marsh edges, and shallow water, sending up dense stands of grassy stems.

Overview

Giant hairgrass is an easy spikerush, taller and thicker-bladed than the dwarf hairgrasses. Its connected clump reads as either a tall midground tuft or a loose background screen.

Did you know

Giant hairgrass can grow as a bog plant in shallow, damp setups or fully submerged in an aquarium. That makes it popular for paludariums.

Caring for giant hairgrass

Push small bunches of giant hairgrass into the substrate and let the runners fill in over time. It is a root feeder, so it does best in a nutrient-rich substrate with root tabs.

Medium light suits it. Brighter light holds it low and dense, while dimmer light lets it grow tall and wild. Its height depends a lot on light and can range from a few inches to well over a foot.

It grows without injected CO2, but CO2 thickens the stand and keeps it shorter. Keep the water at 64 to 82°F (18 to 28°C). To propagate it, split a large clump into smaller ones and plant them separately.

Good to know

Giant hairgrass is a spikerush, and spikerushes are sedges. Its upright green blades are really leafless stems, each tipped by a small flower spike. The plant knits itself together by sending out runners that root and sprout new stems.

In the wild

Giant hairgrass is a spikerush from the Americas. It grows in wet sand, along marsh edges and in shallow water, where it sends up dense stands of grassy stems.

Common questions

Does giant hairgrass need to be planted in the substrate?

Yes. Push the roots into the substrate and keep the rhizome at the surface or just under it, with the growing tip uncovered.

Does giant hairgrass need CO2?

No, but it helps. Giant hairgrass can grow without injected CO2, and added CO2 makes it grow faster.

How much light does giant hairgrass need?

Giant hairgrass wants medium light. A light sold for planted tanks covers it.

Does giant hairgrass need root tabs?

Yes. Giant hairgrass draws much of its food through its roots. Push root tabs in near it, or grow it in a nutrient-rich soil.

How do you propagate giant hairgrass?

Giant hairgrass propagates by runners and division. New plants grow along its runners. Cut one free once it has roots and plant it. Split a large clump into smaller ones and plant them separately.