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Powdery Thalia

Thalia dealbata

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Powdery Thalia (Thalia dealbata) at Randy's Perennials

Powdery Thalia flowers

Powdery Thalia flowers

(Photo courtesy of NetPS Plant Finder)

Powdery Thalia (Thalia dealbata) at Randy's Perennials

Powdery Thalia in bloom

Powdery Thalia in bloom

(Photo courtesy of NetPS Plant Finder)

Plant Height:  6 feet

Flower Height:  10 feet

Spread:  6 feet

Sunlight:  full sun 

Hardiness Zone:  5b

Other Names:  Hardy Canna, Powdery Alligator Flag


This evergreen, marginal aquatic plant forms a clump of long-stalked, erect, narrowly oval leaves covered in white powder; produces slender stems with small clusters of purple flowers in summer; great for rich, wet soils or on a pond perimeter

Ornamental Features

Powdery Thalia features dainty spikes of violet flag-like flowers at the ends of the stems in mid summer, which emerge from distinctive deep purple flower buds. Its attractive large oval leaves remain bluish-green in color with distinctive light green veins throughout the year. The fruit is not ornamentally significant.

Landscape Attributes

Powdery Thalia is an herbaceous evergreen perennial with an upright spreading habit of growth. Its wonderfully bold, coarse texture can be very effective in a balanced garden composition.

This plant will require occasional maintenance and upkeep, and should be cut back in late fall in preparation for winter. It is a good choice for attracting bees and butterflies to your yard. It has no significant negative characteristics.

Powdery Thalia is recommended for the following landscape applications;

  • Mass Planting
  • General Garden Use
  • Water Gardens
  • Bog Gardens

Planting & Growing

Powdery Thalia will grow to be about 6 feet tall at maturity extending to 10 feet tall with the flowers, with a spread of 6 feet. It has a low canopy with a typical clearance of 1 foot from the ground. It grows at a fast rate, and under ideal conditions can be expected to live for approximately 10 years.

This plant should only be grown in full sunlight. It prefers to grow in moist to wet soil, and will even tolerate some standing water. It is not particular as to soil pH, but grows best in rich soils. It is somewhat tolerant of urban pollution. Consider applying a thick mulch around the root zone in winter to protect it in exposed locations or colder microclimates. This species is native to parts of North America. It can be propagated by division.

Hardiness Zone Plant Height Minimum Sunlight
Massing  Garden  Bog  Water 
Flowers  Foliage Color  Texture  Attracts Wildlife 
Ornamental Features