Persicaria
Knotweed
Also known as Polygonum
- Height × spread
- 0.15m – 2.5m × 0.3m – 2m
- Position
- Full sun
Availability
Please ask in store about availability
Many plants are seasonal. Call 01234 567890 to check current stock.
About this plant
These are characterized by their slender columns of closely packed flowers that are in shades of red, pink and more or less white. There are low growing plants, such as Persicaria affinis, often used for mass ground cover and spectacular when seen in full flower. The larger forms come with much larger leaves and can make substantial foliage mounds with more informal long and slim flower spikes that can reach around 1.2 metres high. Bigger still is frothy flowered Persicaria polymorpha that reaches around 1.8 metres high and is a later summer spectacle. In addition to these are a range of shade tolerant plants that often have showy foliage, including Persicaria virginiana and its varieties which have intriguingly variegated foliage.
- Flower colour
- Orange, Pink, Red, White
- Foliage colour
- Gold, Green, Grey, Mahogany, Red, Yellow
- Fruit colour
- Brown, Pink
- Variegated
- No
- Scent
- Yes, some varieties
- Shape
- Bell, Cube, Dome
- Height
- 0.15m – 2.5m
- Spread
- 0.3m – 2m
- Season of interest
- Summer, Autumn, Winter
- Evergreen
- Deciduous
- Garden style
- Wild flower meadow, Shady court, Seaside garden, Rock garden, Prairie garden, Cottage garden
- Sun or shade
- Likes full sun, likes part shade, tolerates light shade
- Soil type
- All types
- Soil pH
- All types
- Drainage
- Moisture retentive soil, Damp and wet soil, Well drained soil, Dry soil
- Winter hardiness
- Varies, some are not hardy
- Borders & containers
- Borders
- Use for
- Ground cover, Architectural, Bee attraction, Butterfly attraction
- Maintenance
- Easycare – low/no maintenance
- Hazards
- No
Spring
Spring - late · Outdoors
Feed with slow release fertiliser
Apply a general purpose slow release fertiliser, spreading it around the root area of the plant as it is coming into growth. (Or apply a liquid feed at regular intervals throughout the growing season.)
This is a simple way to provide a nutrient boost as a single annual procedure.
Spring-Autumn · Outdoors
Water in dry periods
Established plants in the ground can cope with 7-10 days of dryness, and shrubs often manage 2 to 3 weeks. Water one section of the garden thoroughly each day rather than a little everywhere. Check plants in pots more often, especially in hot weather.
Spring-Autumn · Outdoors
Water to keep the soil moist
For best results, this plant needs soil that is always moist. Water deeply and regularly as soon as soil appears dry. Even for established plants in the ground, a dry week can cause problems with some soils. Check plants in pots more often, especially in hot weather. Or install an automatic irrigation system which will do the hard work for you, even when you are away on holiday.
Without regular watering some plants never fully regain their beauty.
Spring - early-mid · Planting
Divide when too large
The plant can be divided if it becomes too large or another plant is required. This may involve physically dividing the clump in two, removing offsets or small bulbs or dividing rhizomes. The new plants can be grown in pots or planted in the ground.
Planting & general
Outdoors
Water some varieties differently
Some plants within this genus have additional requirements for water. It is best to look up your specific plant, or the species it belongs to for watering guidance.
Found in
More Persicaria
Persicaria affinis 'Darjeeling Red'
Himalayan fleece flower, Knotweed
Persicaria affinis 'Donald Lowndes'
Himalayan Fleece flower
Persicaria affinis 'Superba'
Himalayan Fleece flower
Persicaria bistorta 'Superba'
Snakeweed, Mad dog skullcap, Adderwort, Red legs, Bistort, Snake root
Persicaria microcephala 'Red Dragon'
Small flowered knotweed
Persicaria 'Pink Elephant'
Knotweed, Hybrid knotweed
Persicaria affinis
Himalayan fleece flower, Knotweed
Persicaria amplexicaulis
Mountain fleece, Red bistort