Persicaria polymorpha
Common Name: knotweed 
Type: Herbaceous perennial
Family: Polygonaceae
Native Range: China, Japan
Zone: 4 to 9
Height: 3.00 to 5.00 feet
Spread: 3.00 to 4.00 feet
Bloom Time: July to August
Bloom Description: White
Sun: Full sun
Water: Medium
Maintenance: Medium
Suggested Use: Naturalize
Flower: Showy
Tolerate: Deer, Drought


Easily grown in average, medium, well-drained soils in full sun. Prefers moist soils. Tolerant of heat, humidity and, once established, some drought. Not considered to be too aggressive as are some other species of Polygonum and Persicaria.

Noteworthy Characteristics

Persicaria polymorpha is a shrubby, clump-forming perennial featuring plumes (panacled racemes) of creamy white flowers reminiscent of goat's beard (Aruncus dioecus) which bloom throughout the summer atop leafy stems typically rising 3-5' (less frequently to 6') tall. Lance-shaped dark green leaves. Synonymous with and sometimes sold as Polygonum polymorphum. Commonly known as knotweed or giant fleeceflower.

Genus name comes from the Latin persica meaning peach-like and sagittata meaning barbed or arrow-shaped in reference to the shape of the leaves.

Specific epithet means variable or of many forms.


No serious insect or disease problems. Taller plants may need some support.


Specimen or group in borders, cottage gardens or naturalized areas. Mass on slopes.