Persicaria affinis (Lesser Knotweed)

Persicaria affinis (Lesser Knotweed) is a mat-forming, semi-evergreen perennial boasting charming spikes, 3 in. long (8 cm), densely packed with tiny flowers over a long season. Blooming for weeks from midsummer to mid-autumn, they open deep rose-red and fade to pale pink as the season progresses before turning brown in the fall. They remain in place on the plant and provide winter interest. The blossoms are borne above the foliage mat of elliptic to lance-shaped, deep green leaves which turn bronze in the fall.

Persicaria affinis (Lesser Knotweed) is a mat-forming, semi-evergreen perennial boasting charming spikes, 3 in. long (8 cm), densely packed with tiny flowers over a long season. Blooming for weeks from midsummer to mid-autumn, they open deep rose-red and fade to pale pink as the season progresses before turning brown in the fall. They remain in place on the plant and provide winter interest. The blossoms are borne above the foliage mat of elliptic to lance-shaped, deep green leaves which turn bronze in the fall. Lesser Knotweed is most effective at the front of the border or as a ground cover in a cool, moist area.

  • Grows up to 6-12 in. tall (15-30 cm) and 2 ft. wide (60 cm) or more. This plant is not as invasive as many of the other species and may be controlled with selective pruning.
  • Full sun to part shade lover, it is best grown in average, moist, well-drained soils. Best flower production in full sun. While drought tolerant, this plant prefers moist, fertile soils that do not dry out.
  • This plant is very versatile and can be used as a groundcover or as an edging specimen, mixed with other spring flowering bulbs and other perennials in partially shaded beds, borderscottage gardens, or city gardens. Provides stability to banks and carpets stones in a rock garden.
  • Virtually pest and disease free. Deer resistant.
  • Propagate by seed, sown in containers in a cold frame in spring, or by division in spring or autumn
  • Native to the Himalayas.

Requirements

Hardiness 3
– 8

Heat Zones 1
– 8

Climate Zones 1, 1A, 1B, 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17
Plant Type Perennials
Plant Family Persicaria – Fleeceflowers
Exposure Full Sun, Partial Sun
Season of Interest Summer (Mid,Late)FallWinter
Height 6"
– 1'
(15cm
– 30cm)
Spread 1'
– 2'
(30cm
– 60cm)
Spacing 18″
– 24″
(45cm
– 60cm)
Water Needs Average
Maintenance Low
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained
Characteristics Showy, Semi-Evergreen
Tolerance Deer, Drought
Garden Uses Banks and Slopes, Beds and Borders, Edging, Ground Covers, Underplanting Roses and Shrubs
Garden Styles City and Courtyard, Gravel and Rock Garden, Informal and Cottage, Traditional Garden