Persicaria

Persicaria

Persicaria

Smartweeds
Genus:	Persicaria
Family:	Polygonaceae
Type:	Annuals and perennials
Light requirements:	Full sun to part shade
Weediness:	Weedy

Smartweeds are a group of plants in the genus Persicaria, which are usually encountered either as wildflowers or as weeds of lawns and gardens. The majority are annuals.

Description

Plants in this genus have swollen nodes and alternate, simple, spearhead-shaped leaves. The small flowers are held above the foliage on spikes, and are either pink or white. Flowers are borne from late spring through mid autumn, the seeds are likewise white or pink. Plants can be prostrate or bushy, depending on growing conditions and species.

Ecology

Smartweeds can be aggressive weeds of lawns and gardens, walkways, and patios, growing in both rich and poor soils.

Uses

Like buckwheat (which is closely related), the smartweeds can be used as a cover crop or green manure source, though self-seeding can become a nuisance if the plants are not mowed down before the seeds mature.

Some species and varieties are also grown as ornamental plants.

Control

• Pulling: Weeds are easy to pull, however they often root at the nodes when growing along the ground. Stems break away easily, and they will regrow from the crown.
• Pre-emergents (organic): Corn Gluten Meal
• Pre-emergents (synthetic): Pre-emergent herbicides are quite effective.
• Systemic herbicides (synthetic): Contact herbicides can be used, but this will not prevent reseeding.
• Disposal: Plants should not be added to cold compost systems if flowers and/or seeds are present.