Dotted smartweed
Persicaria punctata · Polygonaceae
The gardener's calendar
Ideal time to plant dotted smartweed: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Deciduous
- Flowering
- July to September
- Adult size
- 40 to 80 cm in height
- Growth
- Fast
- Hardiness
- Good, down to -15°C
- Origin
- Southeast Asia
- Soil type
- Moist, rich in organic matter
Care
Watering
Keep the soil constantly moist without waterlogging it. Water regularly during the growing period, especially in summer. Reduce watering in winter. This plant enjoys humid environments and even tolerates slightly marshy areas.
Light exposure
Place your spotted knotweed in full sun or partial shade. It will tolerate light shade but will flower more abundantly in full sun. Protect it from strong winds that could damage its delicate stems.
Soil
Prefer rich, slightly acidic to neutral soil that is well-draining yet retains moisture. Incorporate compost or peat when planting to improve texture. This plant thrives near water features and in humid areas of your garden.
Pruning and cutting
Prune lightly in spring to encourage a compact, branched form. Remove faded flowers to encourage continuous blooming. In late autumn, cut the plant back to ground level before winter.
Fertilizer
A balanced fertilizer application in spring is generally sufficient. You can enrich the soil with well-decomposed compost at the start of the season. Avoid excess nitrogen, which would promote foliage at the expense of flowers.
Diseases and pests
This plant is generally robust. Watch for powdery mildew in overly dry conditions, and aphids on young shoots. Prolonged excess moisture can promote rot: ensure good soil drainage.
Did you know?
The spotted knotweed gets its common name from the tiny reddish dots that speckle its leaves and stems, giving the plant a delicately spotted appearance. From the genus Persicaria (from the Latin persica, peach), these plants have long served as a basis for natural dyes in Asia, particularly for tinting fabrics and leather.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
Add this plant to my garden →Plants from the same family
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- Pink knotweedPersicaria capitata
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- Maidenhair vineMuehlenbeckia complexa
- Red bistortBistorta amplexicaulis
Tips generated and checked by Viridia — adapt them to your local climate.