Dormancy

    Annual Sowthistle

    Sonchus oleraceus

    Annual Sowthistle

    Annual sowthistle (Forest and Kim Starr, Starr Environmental, Bugwood.org)

    Annual Sowthistle

    Annual sowthistle flowers and seeds (Chris Evans, University of Illinois, Bugwood.org)

     

    Description

    • plant with upright growth between 1 and 4 feet in height
    • hollow stems branch toward the sky and produce elongated Hershey kiss-shaped heads that open to yellow, dandelion-like flowers
    • flowers mature to globe-shaped fluffy white seed heads
    • each brown seed is carried in the wind by a tuft of white fluff
    • leaves are green to bluish-green in color, toothed and have prickly margins

    Location

    • commonly grows in planting beds

    Life Cycle

    • annual with germination from spring to fall; peak germination occurs in late spring
    • seedlings form a rosette 6 weeks post germination and produce flowers 9 weeks post germination
    • flower heads continue to bloom from mid-summer to mid-fall; flowers open for 2 days and seed production occurs 1 week after blooms open

    IPM Recommendations

    • Hand-pull plants in planting beds prior to seed maturation.
    • Shallow tillage or hoeing will control young plants in planting beds.
    • Apply a mulch layer 3 inches deep on planting beds to reduce seed germination.
    • Apply an appropriate post-emergent herbicide directly to target weeds.