Vallisneria

Overview

Vallisneria (Vallisneria spiralis) is the classic background grass — long, ribbon-like leaves that rise to the surface and sway in the current, forming a lush green jungle backdrop. It is fast, hardy and thoroughly low-tech, spreading by runners to fill the back of a tank with no CO2 and only modest light. For a natural, grassy background in a beginner tank, few plants beat it.

Planting & placement

Plant vallis along the background, roots in the substrate but with the crown (the pale collar where leaves meet roots) at or just above the surface — burying the crown makes it rot. It is a root feeder, so root tabs help in inert gravel. Give it room: the leaves grow tall and long, and runners quickly fill the space. See how to plant aquarium plants for setting crown depth.

Light, CO2 & ferts

Vallisneria thrives in low to medium light with no CO2. Feed root tabs in the substrate plus a light liquid fertilizer. One caution: vallis can be sensitive to liquid-carbon (glutaraldehyde) additives, which may cause it to melt — if you dose those, go easy or skip them for this plant.

Propagation & problems

Vallisneria propagates itself enthusiastically by runners, sending daughter plants up through the substrate. To manage or expand it, lift the young plants and replant them where you want them, or thin the jungle to keep flow open. Rather than cutting leaves short (which just leaves blunt tips), remove whole outer leaves at the base to tidy it. Main problems: melt from a buried crown or liquid-carbon sensitivity. Pair it with the shorter dwarf sagittaria for a graduated grassy look. Vallisneria can spread vigorously, so thin the runners every few weeks if you want to keep it from taking over the tank. When the tall leaves reach the surface they often bend and grow along it, creating a shaded canopy that fish appreciate and that softens the light for plants below.