A weed is generally defined as any plant growing in a location where it is not desirable. A variety of grasses, sedges and broadleaf weeds continually attempt to invade most turfgrass areas. The life cycles of these weeds include annuals, biennials and perennials.
Annual plants complete their life cycle from seed in less than one year.
Common annual grass weeds include the crabgrass, foxtails, barnyardgrass, goosegrass and some biotypes of annual bluegrass. A wide variety of annual broadleaf weeds are often found in turfgrass areas. Biennial weeds require two years to complete their life cycle. The first year the weeds grow leaves and roots and store energy reserves. The second year flowers and seeds are produced and the plant dies.