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Persicaria alpina (Alpine Knotweed)

Alpine Knotweed, Giant Fleeceflower, Polygonum alpinum, Polygonum polymorphum, Persicaria polymorpha

AGM Award
Persicaria polymorpha, Alpine Knotweed, Giant Fleeceflower, Polygonum alpinum, Polygonum polymorphum, Persicaria alpina, Fall perennial, Summer Perennial
Persicaria polymorpha, Alpine Knotweed, Giant Fleeceflower, Polygonum alpinum, Polygonum polymorphum, Persicaria alpina, Fall perennial, Summer Perennial

Persicaria alpina (Alpine Knotweed) is a tall semi-evergreen, perennial boasting sturdy branching stems clothed with large, lance-shaped, green leaves. In midsummer, stately plumes of small creamy-white flowers are on display for weeks, if not months. They are followed by pinkish-red seed heads in late summer. Clump-forming and low maintenance, this spectacular perennial is tolerant of heat, humidity, and, once established, some drought. Unlike other species of Persicaria, it is not considered invasive, but it does require some room to grow. Perfect for the back of the border or as a flowering hedge.

  • Recipient of the prestigious Award of Garden Merit of the Royal Horticultural Society
  • Grows up to 3-5 ft. tall and wide (90-150 cm) and 3-4 ft. wide (90-120 cm). Provide ample room for it to grow to its full potential.
  • Thrives in any moist soils in full sun or partial shade.
  • This is a welcomed addition to beds and borders, city gardens, cottage gardens, and gravel gardens. This is also an ideal candidate along ponds and streams or in naturalistic meadows.
  • Low maintenance, it is also pest and disease free. Deer resistant.
  • Cut back after flowering.
  • All plant parts may cause skin irritation on contact and stomach upset if ingested.
  • Native to the Himalayas.

 

Requirements

Hardiness 4 - 9
Plant Type Perennials
Plant Family Polygonaceae
Genus Persicaria
Common names Knotweed
Exposure Full Sun, Partial Sun
Season of Interest Summer (Mid, Late)
Fall
Height 3' - 5'
(90cm - 150cm)
Spread 3' - 4'
(90cm - 120cm)
Spacing 36" - 48"
(90cm - 120cm)
Maintenance Low
Water Needs Average, High
Soil Type Clay, Loam
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Poorly Drained
Characteristics Cut Flowers, Plant of Merit, Showy, Semi-Evergreen
Tolerance Drought, Deer
Garden Uses Beds And Borders, Hedges And Screens, Wall-Side Borders
Garden Styles Prairie and Meadow, Gravel and Rock Garden, Informal and Cottage, City and Courtyard
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Alternative Plants to Consider

Persicaria amplexicaulis ‘Atrosanguinea’ (Mountain Fleece)
Persicaria affinis ‘Superba’ (Lesser Knotweed)
Persicaria affinis (Lesser Knotweed)
Persicaria amphibia (Amphibious Bistort)
Persicaria virginiana (Virginia Knotweed)
Persicaria odorata (Asian Mint)

Recommended Companion Plants

Eupatorium maculatum (Atropurpureum Group) ‘Riesenschirm’ (Joe-Pye Weed)
Allium ‘Mount Everest’ (Ornamental Onion)
Euphorbia palustris (Marsh Spurge)
Miscanthus sinensis var. condensatus ‘Cosmopolitan’ (Chinese Silver Grass)

Find In One of Our Guides or Gardens

Persicaria amplexicaulis (Mountain Fleece)
While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.
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Requirements

Hardiness 4 - 9
Plant Type Perennials
Plant Family Polygonaceae
Genus Persicaria
Common names Knotweed
Exposure Full Sun, Partial Sun
Season of Interest Summer (Mid, Late)
Fall
Height 3' - 5'
(90cm - 150cm)
Spread 3' - 4'
(90cm - 120cm)
Spacing 36" - 48"
(90cm - 120cm)
Maintenance Low
Water Needs Average, High
Soil Type Clay, Loam
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Poorly Drained
Characteristics Cut Flowers, Plant of Merit, Showy, Semi-Evergreen
Tolerance Drought, Deer
Garden Uses Beds And Borders, Hedges And Screens, Wall-Side Borders
Garden Styles Prairie and Meadow, Gravel and Rock Garden, Informal and Cottage, City and Courtyard
How Many Plants
Do I Need?
Explore Great Plant Combination Ideas
Persicaria
Guides with
Persicaria
Not sure which Persicaria to pick?
Compare Now

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