Propagating Eleocharis montevidensis (Montevideo Hairgrass) by Runners

How to propagate the tall Montevideo hairgrass through its spreading rhizomes and runners: dividing the mat into plugs and feeding the roots for a dense background meadow.

Overview

Eleocharis montevidensis is a rhizomatous perennial herb that forms tufts or mats of erect, firm stems up to half a meter tall. Like other spikerushes in the genus, it has photosynthetic stems but no true green leaves, the leaves being reduced to sheaths around the base of the stems. In the aquarium it builds a tall, grassy background meadow that spreads steadily across the substrate.

In nature it grows in moist, sandy environments such as lake margins, riverbanks, wet meadows and springs across the Americas, so it is well adapted to a nutrient-rich, waterlogged rooting zone.

Propagation Method: Runners

This species spreads vegetatively through rhizomes, the underground stems that let it form expanding tufts and mats. As the rhizomes creep outward they push up new upright stems, so a single planting gradually thickens into a continuous turf. Propagation is simply a matter of letting that mat establish and then dividing it.

Step-by-Step

Let the original planting grow until the rhizomes have knitted into a dense mat of upright stems.
Gently lift a section of the mat, or reach in and tease the rhizomes apart underwater to limit clouding.
Divide the mat into small plugs, each holding a few stems with attached rhizome and roots.
Replant each plug into the nutrient-rich substrate, spacing them a few centimetres apart so they can fill in.
Press the rhizomes lightly into the substrate so the new plugs stay anchored while they root.

Conditions for Healthy Growth

Substrate: a nutrient-rich, sandy rooting zone suits this fibrous-rooted feeder.
Temperature: 18-28 C.
pH 6.0-7.8, GH 3-14.
Lighting: medium light keeps the stems upright and dense.
It is a fast grower and can also grow emersed.

Maintenance

Trim the meadow roughly every two weeks to keep the blades even and to encourage thicker, lower spreading. Periodically thinning the mat and replanting the divided plugs prevents the centre from becoming congested and shaded out.

Common Challenges

As a strong root feeder in a fibrous-rooted, rhizomatous plant, sparse or pale growth usually points to a poor or exhausted substrate rather than the water column. A dense, undivided mat can also shade and starve its own centre, so regular splitting keeps it vigorous.