Himalayan fleeceflower (knotweed groundcover) Bistorta affinis
Himalayan fleeceflower (knotweed groundcover) (Bistorta affinis) is an evergreen perennial groundcover in the Polygonaceae family, native to Himalaya from Afghanistan to Tibet. It grows 15–25 cm (6–10 in) tall and 40–60 cm (16–24 in) wide, wants part sun to part shade and moderate water, and is hardy to about -30 °C (-22 °F). Space plants about 35 cm (14 in) apart.
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Himalayan fleeceflower (knotweed groundcover) at a glance
| Type | Perennial groundcover, evergreen |
|---|---|
| Family | Polygonaceae |
| Mature height | 15–25 cm (6–10 in) |
| Mature spread | 40–60 cm (16–24 in) |
| Spacing | 35 cm (14 in) centre to centre |
| Sun | Part sun to part shade, at least 4 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance low |
| Soil pH | 5–7.5 |
| Cold hardiness | About -30 °C (-22 °F) once established (roughly USDA zone 4) |
| Heat stress | Likely above about 30 °C (86 °F) |
| Flowering | from about July for 10–16 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Moderate |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | Himalaya from Afghanistan to Tibet |
| Common in gardens of | 🇬🇧 United Kingdom, 🇮🇪 Ireland, 🇺🇸 United States, 🇳🇱 Netherlands, 🇩🇪 Germany, 🇸🇪 Sweden, 🇳🇴 Norway |
Is Himalayan fleeceflower (knotweed groundcover) toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
No poisoning reported; like many in the dock family it contains some oxalates.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Himalayan fleeceflower (knotweed groundcover)
No well-documented helpful pairing. Group it with plants that like part sun to part shade and moderate water.
Questions about Himalayan fleeceflower (knotweed groundcover)
- How far apart should I plant Himalayan fleeceflower (knotweed groundcover)?
- About 35 cm (14 in) apart, centre to centre. A mature plant spreads 40–60 cm (16–24 in).
- Does Himalayan fleeceflower (knotweed groundcover) need full sun?
- Part sun to part shade: at least 4 hours of direct sun a day.
- How much water does Himalayan fleeceflower (knotweed groundcover) need?
- Moderate water. Drought tolerance is low and waterlogging tolerance low.
- How cold-hardy is Himalayan fleeceflower (knotweed groundcover)?
- It tolerates about -30 °C (-22 °F) once established, roughly USDA zone 4.
- When does Himalayan fleeceflower (knotweed groundcover) flower?
- From about July for 10–16 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Himalayan fleeceflower (knotweed groundcover) poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. No poisoning reported; like many in the dock family it contains some oxalates.
- What grows well with Himalayan fleeceflower (knotweed groundcover)?
- There is no well-documented companion pairing for Himalayan fleeceflower (knotweed groundcover). Group it with plants that like the same sun (part sun to part shade) and water (moderate).
Sources and evidence
Evidence grade A (A: strong evidence).
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- Flora of Nepal (online flora and checklist), Royal Botanic Garden Edinburgh with Nepalese and international partners
- RHS Find a Plant (plant profiles and growing guides), Royal Horticultural Society
Notes and assumptions
- A tough mat of narrow leaves with upright pink pokers that age to deep red from midsummer to autumn; the leaves turn bronze-red in winter (‘Superba’, ‘Darjeeling Red’). Good on banks, edges and rock gardens; not invasive like its giant relative Japanese knotweed.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
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