Overview
Polygonum amplexicaule 'Atrosanguineum' is a mat-forming, clump-forming or tall and upright perennial in the genus Polygonum, part of the Polygonaceae family, with deciduous; simple, lance-shaped to heart-shaped, often marked or autumn-tinted foliage. It typically grows around 1.2 metres tall. Polygonum amplexicaule 'Atrosanguineum' grows best in full sun to partial shade, and tolerates almost any soil and including heavy clay soils and acid and neutral or alkaline pH. Its UK hardiness is rated H5-H7. Suggested uses include borders, cottage gardens, wildflower gardens and damp areas. It is native to China, Himalayas and Pakistan.
About
Polygonum amplexicaule 'Atrosanguineum' is a perennial from the buckwheat family that tolerates damp soil and reaches about 1.2 metres. It can grow as a mat, a clump or a taller upright plant and has deciduous, lance- to heart-shaped leaves that often show marking or autumn tints. Flowering occurs from July to September on narrow spikes carried above the foliage. It suits a range of soil types, including heavy clay, and favours moist conditions over drought.
Wikipedia contributors, CC BY-SA 4.0 — Bistorta amplexicaulis
About the genus
Polygonum is a genus of about 130 species of flowering plants in the buckwheat and knotweed family Polygonaceae. Common names include knotweed and knotgrass. In the Middle English glossary of herbs Alphita, it was known as ars-smerte.
Wikipedia contributors, "Polygonum", CC BY-SA 4.0 — Polygonum
In the garden
Polygonum amplexicaule 'Atrosanguineum' is a perennial native to China, the Himalayas and Pakistan, placed in the Polygonaceae family. Plants may form low mats, tidy clumps or develop into taller, upright stems; the foliage is deciduous and typically lance- to heart-shaped, sometimes showing markings or autumn colour. Expect flowering from July to September. Give it full sun to partial shade on almost any soil, including heavy clay; it tolerates acid, neutral or alkaline pH. The plant prefers moist ground and most varieties cope with damp situations but dislike prolonged drought, so sit it where soil stays reasonably damp or provide supplementary water in dry spells. Aspect and exposure are flexible: it performs in both sheltered and more exposed spots. In the garden use Red Bistort at the back of a mixed border, in cottage or wildflower plantings, or beside ponds and channels where soil remains damp. Allow room for stems to reach roughly 1.2 metres so flower spikes can be displayed above neighbouring perennials. It is suitable for UK locations rated H5 (hardy) through H7 (fully hardy), making it a reliable summer-flowering presence in wetter parts of the plot.
Growing conditions
Best soil and position for Polygonum
- Sunlight
- Full sun to partial shade
- Soil type
- Almost any soil, including heavy clay
- Soil pH
- Acid, neutral or alkaline
- Soil moisture
- Moist; most tolerate damp ground and dislike drought
- Aspect
- Any
- Exposure
- Exposed or sheltered
- UK hardiness
- H5-H7
Plant details
Polygonum amplexicaule 'Atrosanguineum' size, habit and characteristics
- Plant type
- Perennial
- Habit
- Mat-forming, clump-forming or tall and upright
- Foliage
- Deciduous; simple, lance-shaped to heart-shaped, often marked or autumn-tinted
- Height
- 1.2 metres
- Suggested uses
- Borders, cottage gardens, wildflower gardens, damp areas
- Native to
- China, Himalayas, Pakistan
Care notes
Pruning and caring for Polygonum amplexicaule 'Atrosanguineum'
- Cultivation
- Undemanding to the point of needing restraint rather than encouragement. Give reliable moisture and they flower for months. Vigour is the main consideration: check the spread of any given species before planting, since the running kinds colonise fast and are difficult to remove once established, while the clump-forming ones are well behaved. Note that most garden knotweeds are now classified under Persicaria.
- Pruning
- Cut back to the base in late autumn, or leave the dried spikes standing for winter interest and clear in early spring. Shear mat-forming kinds after the first flush to tidy them.
- Propagation
- Divide in spring or autumn - most divide very easily. Basal cuttings root readily in spring.
- Pest resistance
- Slugs graze new growth; otherwise notably trouble-free.
- Disease resistance
- Healthy and robust. Powdery mildew occurs on plants that dry out.
Frequently asked questions
How do I grow Polygonum amplexicaule 'Atrosanguineum'?
Undemanding to the point of needing restraint rather than encouragement. Give reliable moisture and they flower for months. Vigour is the main consideration: check the spread of any given species before planting, since the running kinds colonise fast and are difficult to remove once established, while the clump-forming ones are well behaved. Note that most garden knotweeds are now classified under Persicaria.
Where is the best place to plant Polygonum amplexicaule 'Atrosanguineum'?
Polygonum amplexicaule 'Atrosanguineum' prefers full sun to partial shade. It suits exposed or sheltered positions.
What soil does Polygonum amplexicaule 'Atrosanguineum' need?
Polygonum amplexicaule 'Atrosanguineum' grows best in almost any soil and including heavy clay soil. It prefers acid and neutral or alkaline soil. Aim for soil that stays moist; most tolerate damp ground and dislike drought.
How do I prune Polygonum amplexicaule 'Atrosanguineum'?
Cut back to the base in late autumn, or leave the dried spikes standing for winter interest and clear in early spring. Shear mat-forming kinds after the first flush to tidy them.
How big does Polygonum amplexicaule 'Atrosanguineum' grow?
Polygonum amplexicaule 'Atrosanguineum' reaches a height of 1.2 metres.
Is Polygonum amplexicaule 'Atrosanguineum' hardy in the UK?
Polygonum amplexicaule 'Atrosanguineum' has an RHS hardiness rating of H5, meaning it is hardy in most of the UK, tolerating -15 to -10°C.
How do I propagate Polygonum amplexicaule 'Atrosanguineum'?
Divide in spring or autumn - most divide very easily. Basal cuttings root readily in spring.
More in the Polygonum genus
- Polygonum affineHimalayan bistort, fleece flower
- Polygonum affine 'Superbum'Knotweed
- Polygonum albinumKnotweed
- Polygonum amplexicaulered bistort, mountain fleece
- Polygonum amplexicaule 'Arun Gem'Red Bistort
- Polygonum amplexicaule 'Firetail'Knotweed
- Polygonum amplexicaule 'Inverleith'Knotweed
- Polygonum amplexicaule oxyphyllum of gardensKnotweed
