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Pigweeds (Amaranthus spp.) are native annual plants that are associated with sites where the soil has been disturbed. Leaves are simple and oval- to lance-shaped with an alternate leaf arrangement. Pigweeds germinate readily from late spring through early autumn, produce numerous seeds, and grow quickly. Seeds of weedy species are small and black. Plants have a primary taproot. 

Pigweed growth habit.

(Photo: Phil Westra, Colorado State University, Bugwood.org)

Management:

• Cultivate when weeds are less than 4 inches tall; cultivation is not effective with larger plants.
• Apply pre-emergent herbicides and spot spray with post-emergent herbicides.
• Some pigweed populations have herbicide resistance. Herbicide resistant populations should be confirmed by a county Extension agent or the Weed Science Society of America.

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