TankBud

Giant vallisneria

Vallisneria australis

Also known as Giant vals, Vallisneria americana var. gigantea, Tape grass, Eelgrass, Vallisneria gigantea

FreshwaterBrackishRosetteRunners

Invasive. A vigorous spreader that is invasive in some warm regions. Never release into the wild; dispose of in the trash.

Giant vallisneria (Vallisneria australis)
Aquarium Plants Factory · Used with permission

Care at a glance

Light
Low light
CO2
No CO₂ needed
Temperature
64–86°F
18–30°C
Max height
59.1 in
150 cm
Growth rate
Fast
Placement
Background
Type
Rosette
pH
6.5–8.5
Hardness
3–20 dGH
Spread
11.8 in (30 cm)
Nutrient uptake
Root feeder
Growth region
Submersed
Difficulty
Beginner
Family
Hydrocharitaceae
Origin
Asia (genus pantropical); plants in the trade are often Vallisneria americana var. gigantea

Overview

Giant vallisneria is a fast-growing beginner plant for the background of tall tanks.

Did you know

Giant vallisneria's female flower reaches the surface on a long spiral stalk, where free-floating male flowers pollinate it. The stalk then corkscrews back down so the seed ripens underwater.

Caring for giant vallisneria

Plant giant vallisneria with the crown in the substrate but the white base of the crown above the gravel, or it can rot. Give it a tall tank, since its strap leaves grow 50 to 150 cm long and will carpet the surface of a shorter one.

It is a heavy root feeder, so root tabs in a nutritious substrate matter far more than liquid dosing. It does fine in low light with no CO2. It handles 64 to 86°F (18 to 30°C) and fresh or brackish water.

Giant vallisneria grows fast and spreads by runners into dense thickets. Thin the runners regularly, or it takes over and shades out its neighbors. Avoid Excel-type liquid carbon supplements with glutaraldehyde, which can melt its leaves while leaving most other plants unharmed.

Good to know

Giant vallisneria is a member of the Hydrocharitaceae and is dioecious, with male and female flowers on separate plants. Its naming is muddled, since the name V. gigantea has been misapplied to both V. australis and the giant variety of V. americana. Much of what is sold as V. gigantea is actually V. americana var. gigantea, and the trade name covers several large-leaved forms. It also goes by tape grass and eelgrass.

In the wild

Giant vallisneria belongs to a pantropical genus of submersed freshwater herbs, found in slow rivers, lakes and ponds across Asia, Australia and the Americas. It grows fully submersed in soft to hard water, often hard and alkaline, rooting in mud or sand. Its ribbon leaves push up to the surface.

Common questions

Does giant vallisneria need to be planted in the substrate?

Yes. Bury the roots and leave the crown, where the leaves join, just above the substrate.

Does giant vallisneria need CO2?

No. Giant vallisneria grows well without added CO2 and suits a low-tech tank.

How much light does giant vallisneria need?

Giant vallisneria is a low-light plant, and the light that comes with a standard tank kit is enough for it.

Does giant vallisneria need root tabs?

Yes. Giant vallisneria 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 vallisneria?

Giant vallisneria propagates by runners. New plants grow along its runners. Cut one free once it has roots and plant it.

How tall does giant vallisneria grow?

Giant vallisneria grows to about 59.1 in (150 cm) tall. It grows fast, so expect to trim it often.

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