Alpine knotweed, Persicaria alpina

Persicaria alpina

Knotweed

A table displaying which months are best to sow, plant and harvest.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Flowers
Flowers

Plant does not flower in January

Plant does not flower in February

Plant does not flower in March

Plant does not flower in April

Plant does not flower in May

Plant does flower in June

Plant does flower in July

Plant does flower in August

Plant does not flower in September

Plant does not flower in October

Plant does not flower in November

Plant does not flower in December

  • Botanical name: Persicaria alpina
  • Common name: Knotweed
  • Family: Polygonaceae
  • Plant Type: Perennial, Semi-evergreen
Flower colour:

White

Foliage colour:

Green

Alpine knotweed, Persicaria alpina, is a substantial herbaceous perennial with pointed green leaves topped by fluffy flower plumes from midsummer and into autumn. Don’t be put off by its common name; Persicaria alpina is easy to grow, but not thuggish or invasive.

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Persicaria alpina enjoys growing in moist soil, so it’s a great choice for growing near ponds, allowing the water to catch its reflection.

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For best results, grow Persicaria alpina in full sun or partial shade in moist, well-drained soil, sheltered from strong winds. Cut back the foliage to the base of the plant after it has been hit by the first frosts.

How to grow Persicaria alpina

  • Plant size

    1.8m height

    1.5m spread

  • Aspect

    North facing, south facing, east facing, west facing

  • Position in border

    Middle

  • Sun exposure: Full sun, partial shade
  • Hardiness: Hardy
  • Soil type: Acidic / chalky / alkaline / clay / heavy / moist

Plant calendar

A table displaying which months are best to sow, plant and harvest.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Sow
Sow

Do not Sow in January

Do not Sow in February

Do Sow in March

Do Sow in April

Do Sow in May

Do not Sow in June

Do not Sow in July

Do not Sow in August

Do not Sow in September

Do not Sow in October

Do not Sow in November

Do not Sow in December

Plant
Plant

Do not Plant in January

Do not Plant in February

Do Plant in March

Do Plant in April

Do Plant in May

Do not Plant in June

Do not Plant in July

Do not Plant in August

Do not Plant in September

Do not Plant in October

Do not Plant in November

Do not Plant in December

Flowers
Flowers

Plant does not flower in January

Plant does not flower in February

Plant does not flower in March

Plant does not flower in April

Plant does not flower in May

Plant does flower in June

Plant does flower in July

Plant does flower in August

Plant does not flower in September

Plant does not flower in October

Plant does not flower in November

Plant does not flower in December

Divide
Divide

Do not Divide in January

Do not Divide in February

Do Divide in March

Do Divide in April

Do Divide in May

Do not Divide in June

Do not Divide in July

Do not Divide in August

Do Divide in September

Do Divide in October

Do Divide in November

Do not Divide in December

Cut back
Cut back

Do not Cut back in January

Do not Cut back in February

Do not Cut back in March

Do not Cut back in April

Do not Cut back in May

Do not Cut back in June

Do not Cut back in July

Do not Cut back in August

Do not Cut back in September

Do Cut back in October

Do Cut back in November

Do not Cut back in December

Persicaria alpina and wildlife

Persicaria alpina has no particular known value to wildlife in the UK.

Is Persicaria alpina poisonous?

Persicaria alpina has no toxic effects reported.

No reported toxicity to:

No reported toxicity to Birds

No reported toxicity to Cats

No reported toxicity to Dogs

No reported toxicity to Horses

No reported toxicity to Livestock

No reported toxicity to People

Plants that go well with Persicaria alpina