Weed Life Cycles

Weeds have one of three life cycles: annual; biennial; or perennial.

Annual weeds live for a single season. There are two types of annuals and both reproduce by seeds.

Winter Annuals - germinate late in the summer or early fall, are dormant during the winter, flower in early spring or early summer, and then die. For example:

• Common Chickweed (Stellaria media)
• Henbit (Lamium amplexicaule)

Summer Annuals - germinate during spring or summer, flower, and die at the end of the growing season. For example:

• Crabgrass (Digitaria spp.)
• Goosegrass (Eleusine indica)
• Prostrate spurge (Euphorbia supina)
• Knotweed (Polygonum aviculare)
• Yellow foxtail (Setaria glauca)

Biennial weeds live for two seasons. During the first growing season, these weeds remain in a vegetative stage. Following a cold treatment (vernalization), biennial weeds bolt, flower, set seed and die during the second growing season. For example:

• Bull thistle (Cirsium vulgare)

Perennial weeds live for multiple seasons and flower more than once. Perennial structures (rhizomes, stolons, crowns, entire plants, nutlets, or roots) survive from year to year. There are two types of perennial weeds:

Cool season perennials - are perennial weeds that grow best in spring and fall. For example:

• Creeping bentgrass (Agrostis palustris)
• Quackgrass (Elytrigia repens)
• Tall fescue (Festuca arundinacea)

Warm season perennials - are perennial weeds that grow best in summer. For example:

• Nimblewill (Muhlenbergia shreberi)