Oval leaf knotweed (Polygonum arenastrum)

Oval leaf knotweed

Also known as: Small leaved wireweed, Small-leaved knotweed

Oval leaf knotweed (Polygonum arenastrum) is an invasive plant native to Europe that can now be found throughout North America as well. It sends out a long tap root that helps make it very drought-tolerant. Oval leaf knotweed prefers dense, compacted soils. Though a bane of large-scale farmers, it can usually be pulled by hand in smaller gardens.

Scientific classification

Species

Oval leaf knotweed (Polygonum arenastrum)

Pinks, cacti, and allies

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Annual, Perennial

Lifespan

Herb

Plant Type

Summer

Bloom Time

15 cm to 30 cm

Plant Height

90 cm to 1.2 m

Spread

2.5 mm

Flower Size

Images of Oval leaf knotweed

Distribution of Oval leaf knotweed

Distribution Map

Oval leaf knotweed is indigenous to various regions across Eurasia, from the Mediterranean and Northern Africa to the temperate zones of Asia, as well as in parts of Europe. The plant has successfully established itself in both Northerly and Southerly areas, thriving in the diverse climates these regions offer. Beyond its native expanses, oval leaf knotweed has been introduced to multiple continents including South America, North America, Oceania, and Africa, where it has adapted to local environments and is often found in the wild.

Native

Cultivated

Invasive

Introduced

No species reported

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Habitat

Waste places, roadsides

Hemisphere Trend Curve

Northern

Sorthern

Culture

Interesting Facts

This plant was found in Philadelphia around 1910. It is a kind of rice field weed that is hard to remove because of its strong viability in wetlands, river banks, grasslands, moors and mudflats.

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Care Guide for Oval leaf knotweed

Every week

Water

Full sun

Sunlight

20 - 35 ℃

Ideal Temperature

Water: Native to temperate regions, oval leaf knotweed thrives in moderate moisture and requires weekly watering. It prefers a balanced water regime, avoiding drought and excess humidity. Outdoor cultivation enhances its growth, benefiting from rainwater during the growing season, which is more suitable than tap water.

Fertilize: Oval leaf knotweed thrives with balanced nutrition fertilizer during its growing season, applying high-nitrogen options sparingly. Monthly half-strength fertilization is ideal, adjusting for seasonal dormancy. Caution is crucial, as over-fertilization can weaken growth. Use slow-release formulas for effective nutrient delivery.

Pruning: Oval leaf knotweed features spreading growth and small, oval leaves. Prune from early to late spring to manage size and promote healthy growth. This enhances air circulation and reduces pest risks. Use clean, sharp tools for effective maintenance and faster recovery.

Propagation: Oval leaf knotweed propagates easily through sowing in a well-draining substrate. Seeds should be lightly pressed and covered with soil. Consistent watering without waterlogging aids germination. Transplant young plants gently to protect roots. Mature plants need minimal intervention when provided adequate space.

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