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Giant vallisneria
BeginnerVallisneria australis
A large vallisneria with tough ribbon leaves about 2 cm wide that grow over 1 m long and spread across the surface. It multiplies freely by runners and resists herbivorous fish. Naturalised in Japan and listed as a Priority Control Alien Species.
About
Giant vallisneria is a submerged plant (Hydrocharitaceae); the plants now traded have been identified as Vallisneria australis from southern Australia. They were long sold as 'Vallisneria gigantea' or 'americana', and genetic analysis has shown that plants sold in Japan as V. gigantea were in fact V. australis; the name gigantea is now treated as a synonym of another species. Size identifies it: tough ribbon leaves about 2 cm wide and 50–150 cm long that reach the surface and spread across it in most tanks. The stiff leaves resist herbivorous fish. It grows fast and, in a rich substrate, sends out runner after runner of daughter plants. It grows in low light without CO2 and suits beginners, but once it covers the surface it shades plants below, so cut overlong leaves at the base. It reached Japan by 2002 and is established in rivers in Tochigi, Gunma, Shiga, Kumamoto and Oita. The Ministry of the Environment's alien species list (2nd ed., September 2026) designates it a Priority Control Alien Species that must not be taken into natural waters, as it may outcompete rare native plants. It is widely sold in aquarium shops in Japan.
Size of the Giant vallisneria
The Giant vallisneria grows to Leaves 50–150 cm long, about 2 cm wide.
Temperature & humidity for the Giant vallisneria
The ideal temperature for the Giant vallisneria is 18〜28℃.
Basic Info
Origin
Southern Australia
Lifespan
Perennial; keeps renewing itself by runners
Size
Leaves 50–150 cm long, about 2 cm wide
Temperature
18〜28℃
Watering & Fertilizer
No CO2 needed; a rich substrate encourages runners
Growing Tips
Lighting
Grows in low light; watch that it does not shade the plants below once it covers the surface.
CO2 & Fertilizer
No CO2 needed; a rich substrate encourages runners.
Water Temperature & Quality
Optimum 18–28°C at pH 6–8.
Substrate & Attachment
Plant in the substrate; its long leaves suit the background of large tanks.
Trimming & Propagation
Separate and replant daughter plants from runners; cut overlong leaves at the base.
Cautions
Listed as a Priority Control Alien Species. Never dump it in rivers or ponds, and dry cut leaves and runners before binning them.
Giant vallisneria FAQ
QWhat is the growing difficulty level for Giant vallisneria?
Beginner. A variety suitable for beginners. No special equipment or experience is required—you can grow it without problems by setting up a basic cultivation environment.
QWhat is the ideal temperature for Giant vallisneria?
The ideal temperature for Giant vallisneria is 18〜28℃. Avoid sudden temperature changes and maintain a stable environment.
QHow large does Giant vallisneria get?
The mature size of Giant vallisneria is Leaves 50–150 cm long, about 2 cm wide. This may vary slightly depending on cultivation environment and individual differences.
QHow should I water and fertilize Giant vallisneria?
Giant vallisneria: watering & fertilizer — No CO2 needed; a rich substrate encourages runners. Aim for appropriate frequency and amount.
QWhat is the typical price for Giant vallisneria?
The price of Giant vallisneria varies significantly by variety, characteristics, size, and lineage. Please check GrowerDirect's price guide for the latest market information.
Last updated: September 23, 2026
References & Sources
Edited & verified by: GrowerDirect Editorial Team
The classifications, regulations, and growing data on this page are created and verified based on the primary information database below.
Taxonomy & Authority
Regulations & Conservation Status
Not listed in CITES (no match in Species+). Designated a Priority Control Alien Species (Vallisneria australis, giant vallisneria) in the Ministry of the Environment's alien species list (2nd ed., September 2026). It is not a Specified Invasive Alien Species and can be sold and grown, but must not be introduced to natural waters because it may outcompete rare native plants. Never dump it in rivers, ponds or ditches.
Sources: Species+ (CITES listing check) / Ministry of the Environment: List of Alien Species that may Damage Ecosystems / Ministry of the Environment: alien species list, plants (2nd ed.)
Regulations may change. Always verify the latest information with the relevant authorities.
Related Species
Find listings for this species
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