WSU Extension

Hortsense

Weeds : Sowthistle, annual and perennial : Sonchus oleraceus, Sonchus arvensis
(revision date: 4/7/2021)

Family: Asteraceae (Compositae)
Cycle: Annual
Plant Type: Broadleaf

Use Integrated Pest Management (IPM) for successful weed management.

Biology
Annual sowthistle grows upright and can reach from one to four feet tall. The lower leaves have a stalk while the upper leaves do not. Most of the leaves are deeply lobed and have one to three lobes on each side. Annual sowthistle produces many pale yellow flower heads that are 1/4 to 3/4 inch wide. The seeds are flat with lengthwise ribs and a parachute-like tuft of fine hairs that aid in wind dissemination. Perennial sowthistle leaves, stems, and flowerheads are often a little larger than annual sowthistle. Perennial sowthistle produces many creeping roots that aid the spread of this creeping perennial species.
Habitat
Sowthistle grows along roadsides, cultivated fields, in gardens and in waste areas throughout Washington.

Management Options

Non-Chemical Management
None recommended
Select non-chemical management options as your first choice!

Chemical Management

Glyphosate products should be applied as spot treatments only! NOTE: Some ingredients listed here are only available in combination. Read the label carefully on combination products to make sure the product is suitable for your specific situation.

Landscape areas
  • glyphosate
Turf areas
  • 2,4-D + MCPP + dicamba
Bare ground areas
  • glyphosate
Images
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Caption: Spiny sowthistle
Photo by: T. W. Miller
Caption: Perennial sowthistle glandular hairs
Photo by: T. W. Miller
Caption: Annual sowthistle flower heads
Photo by: T. W. Miller
Caption: Annual sowthistle leaf at base of stem
Photo by: J.A. Kropf
Caption: Line drawing of annual sowthistle
Photo by: Ciba Geigy
Caption: Annual sowthistle flower
Photo by: T. W. Miller
Caption: Annual sowthistle
Photo by: C.R. Foss
Caption: Annual sowthistle mature head
Photo by: T. W. Miller