Propagating Vallisneria australis (Australian Tape Grass)

How to propagate Vallisneria australis from runners and daughter rosettes, with the bright light, root feeding and planting tips this tape-grass rosette needs.

Overview

Vallisneria is a submerged rosette plant whose leaves arise in clusters from the roots, with rounded tips and raised veins. Vallisneria australis, the Australian tape grass, is a giant form whose ribbon leaves can exceed one metre, making it a striking background plant for tall display tanks.

It is a fast-growing root feeder that does best under bright illumination but still grows, more slowly, under moderate light. It does not require CO2 and tolerates neutral to alkaline, moderately hard, cool-to-warm water, disliking very acidic conditions.

Propagation Method

Vallisneria spreads by runners, producing daughter plants at the ends of those runners. Propagation means letting these daughter rosettes form and then cutting them away to transplant, rather than topping or cutting the leaves of the parent. Over a few months the runners knit the substrate into dense growth.

Step-by-Step

Plant a parent rosette in a back corner and let it establish.
Wait for runners to push out across the gravel and form daughter rosettes at their tips.
Once a daughter rosette has its own leaves and roots, cut the connecting runner.
Lift the daughter plant and replant it where you want new growth, keeping the crown at substrate level and the roots buried.
Feed and light it well so it roots in and sends out its own runners.

Conditions for Healthy Growth

Lighting: a high-quality planted-aquarium LED; brightest growth under strong light, slower under moderate light.
Feeding: it is a root feeder and must be fed, for example with an all-in-one fertiliser or in tanks with a heavy fish load; plain gravel works if iron-rich fertiliser is added.
CO2: not required.
Water: neutral to alkaline, moderately hard; pH about 6.5-8.2, GH 5-18, temperature 16-28 C; it dislikes very acidic water.
Crown: keep the crown at the substrate surface so it is not buried.

Maintenance

Once established it will keep spreading through the gravel, so thinning is the main task. Pull up stray daughter plants where you do not want them and replant or share the excess; the plant is easy to remove and propagates fast enough that hobbyists routinely have spares to give away.

Common Challenges

Underfeeding: as a root feeder it will languish without fertiliser, especially in lean substrates.
Buried crown: planting the crown too deep can rot the plant; keep it at substrate level.
Spreading too far: vigorous runners will colonise the whole tank unless you thin them, though they are easy to pull out.