KNOTWEED

FAMILY: Polygonaceae | GENUS: PERSICARIA

TYPE
  • Perennials
SUN EXPOSURE
  • Full Sun
  • Partial Shade
WATER
  • Regular Water

Plant Details

Sturdy plants with jointed stems and small white or pink flowers. Some kinds tend to get out of hand and need to be controlled.

persicaria affinis

  • Himalayan Knotweed.
  • Zones US, MS, LS; USDA 6-8.
  • Himalayan native.
  • Spreading plant to 1 feet high, 2 feet or more wide.
  • Deep green, lance-shaped, finely tooth-edged leaves are mostly basal; they grow 2412 inches long, turn bronze in winter.
  • Dense, erect, 2- to 3 inches spikes of bright rosy red flowers bloom in summer, early fall.
  • Informal border or ground cover.
  • Darjeeling Red forms 3 inches-high foliage mats, has 10 inches spikes of deep pink flowers that age to red; its foliage turns red in fall.
  • Dimity sports pale pink flowers and larger leaves than the species.

persicaria alpina(Persicaria polymorpha) Alpine Knotweed

  • Zones US, MS, LS, CS; USDA 6-9.
  • Native to China, Japan.
  • To 46 feet tall, 4 feet wide.
  • Forms a bushy clump of rough-textured, lance-shaped, dark green leaves to 8 inches long.
  • In summer, sturdy stems are topped by big, fluffy, creamy white flower plumes reminiscent of astilbe.
  • Not invasive.
  • Tolerates heat and humidity.

persicaria amplexicaulis

  • Mountain Fleece.
  • Zones US, MS; USDA 6-7.
  • Himalayan native.
  • Forms a big clumpto 4 feet tall and wide when plants are in flower.
  • Medium green leaves are pointed ovals up to 10 inches long.
  • Blooms profusely from midsummer to fall, bearing narrow, 4 inches blossom spikes similar to those of lavender (Lavandula) but in a wider range of colorspink, purple, red, white.
  • Firetail has bright scarlet flowers.

persicaria bistorta

  • Bistort.
  • Zones US, MS; USDA 6-7.
  • Native to Eurasia.
  • Makes a clump to 212 feet tall, 3 feet wide, with broadly oval, medium green, 4- to 12 inches-long leaves.
  • Tight, 2- to 3 inches spikes of pale pink or white flowers bloom from late spring until well into summer.
  • Superba is a good pink selection.

persicaria capitata

  • Pink Knotweed.
  • Perennial in Zones US, MS, LS, CS; USDA 6-9; annual elsewhere.
  • Himalayan native.
  • Tough, trailing ground cover grows 36 inches high, spreading indefinitely both by rooting stems and by self-seeding.
  • Oval, 112 inches-long leaves are dark green when new, take on pinkish overtones when mature.
  • Leaves of all ages have a bronzy cast that deepens in cooler weather; they discolor and die below 28F.
  • Stems and small, round flower heads are pink.
  • Blooms almost all year in mild climates.
  • Best in confined spots (where it won't be able to spread) or in uncultivated areas.
  • No watering needed.

fleece flower

persicaria microcephala

  • Perennial.
  • Zones US, MS, LS, CS; USDA 6-9.
  • Red Dragon is the poster child of the species and a striking addition to a sun- to-part shade bed.
  • Dark burgundy foliage is the reason to grow it, although it does have small white flowers in late summer.
  • It does not spread underground, remaining in a clump unless a stem bends over and puts down roots.
  • Well-behaved to 3 feet tall.

creeping fleece flower

persicaria vacciniifolia

  • Zones US, MS, LS; USDA 6-8.
  • Himalayan native.
  • Prostrate plant forms a foliage mat to 3 inches high, trailing to 2 feet or wider.
  • Slender, branching, reddish stems are clothed in oval, 12 inches-long, shiny green leaves that turn red in fall.
  • In late summer, 6- to 9 inches flower stalks bear dense, upright, foxtail-like, 2- to 3 inches spikes of rose-pink blossoms.
  • Excellent as a bank cover or for draping over a boulder in a large rock garden.

virginia knotweed

persicaria virginiana

  • Zones US, MS, LS; USDA 6-8.
  • Native to eastern North America, eastern Asia.
  • To 24 feet tall, spreading indefinitely by creeping rhizomes.
  • Oval green leaves 310 inches long; insignificant flowers.
  • The species is rarely found in gardens.
  • More commonly seen is 'Painter's Palette', valued for its flashy foliage: Leaves are marbled in green, pale gray- green, and ivory, with a ragged chocolate-maroon V in the center.
  • On new growth, the ivory patches are closer to yellow, and the central V-shaped mark has a pink cast.

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