Thalia dealbata Powdery alligator flag/Hardy water canna


A striking plant with large glaucous leaves and small purplish flowers held high on long thin stems. This semi-hardy plant can stay outside providing the roots are deep enough in the water to avoid the frost level.

Repotting or planting

9cm marginal plants require potting into a larger mesh basket. Place in a pond no deeper than 1/3 maximum recommended planting depth to allow the plants to establish. 1ltr marginal plants do not require repotting, place in pond no deeper than 1/2 maximum recommended planting depth to allow the plants to establish. 3ltr and 5ltr plants do not require repotting, as they are larger more established plants they can be placed up to the maximum recommended depth. There is no need to remove the mesh basket.

Care instructions

Protect from frost as described above or place inside in water with as much light as possible or cut back and store in damp sand or peat for winter.



Growth rate



June – Aug


Full sun


Spring, Summer

Measurements in centimetres

Height Min –Max


Depth Min-Max


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Covid19 Update:
Plants ordered by Sunday will be dispatched by Wednesday.