Polygonum amplexicaule 'Arun Gem' (Red Bistort) — Mat-forming, clump-forming or tall and upright

Overview

Polygonum amplexicaule 'Arun Gem' 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 'Arun Gem' 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. It is native to China, Himalayas and Pakistan.

About

Polygonum amplexicaule 'Arun Gem' is a moisture-preferring perennial knotweed that can form mats, clumps or grow more upright to about 1.2 metres. The leaves are deciduous, lance- to heart-shaped and often show markings or autumn tint. It flowers from July to September, giving a summer display. Plants tolerate a wide range of soils, including heavy clay, but dislike 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 'Arun Gem' belongs to the Polygonaceae family and originates from China, the Himalayas and Pakistan. It is a perennial that may spread as a mat or clump or hold a taller, more upright form, reaching roughly 1.2 metres at maturity. The foliage is deciduous and can develop marked or autumn-tinted colours as the season progresses. Give it full sun to partial shade in any aspect and in soils that retain moisture; many specimens tolerate heavy clay and a wide soil pH range from acid to alkaline. Plants suit exposed as well as sheltered sites but will not do well in drought conditions, so keep soil consistently moist for best performance. Hardiness is H5–H7, meaning it is hardy to very hardy and can be grown outdoors across most of the UK. Use Polygonum amplexicaule 'Arun Gem' in moisture-retentive borders where its 1.2 metre height can form a mid- to rear-border element or in damp planting zones where lower perennials sit beneath it. Flowering takes place from July to September, providing a sustained summer-to-early-autumn presence; position the plants where that seasonal display will be visible above lower neighbours.

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 'Arun Gem' 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
Native to: China, Himalayas, Pakistan

Care notes

Pruning and caring for Polygonum amplexicaule 'Arun Gem'

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 'Arun Gem'?

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 'Arun Gem'?

Polygonum amplexicaule 'Arun Gem' prefers full sun to partial shade. It suits exposed or sheltered positions.

What soil does Polygonum amplexicaule 'Arun Gem' need?

Polygonum amplexicaule 'Arun Gem' 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 'Arun Gem'?

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 'Arun Gem' grow?

Polygonum amplexicaule 'Arun Gem' reaches a height of 1.2 metres.

Is Polygonum amplexicaule 'Arun Gem' hardy in the UK?

Polygonum amplexicaule 'Arun Gem' 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 'Arun Gem'?

Divide in spring or autumn - most divide very easily. Basal cuttings root readily in spring.

More in the Polygonum genus

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