Selective herbicides are used for effective control, along with some good management practices. Another characteristic of weeds is whether they thrive in cool or warm weather. A cool season annual like annual bluegrass thrives in spring and fall seasons when weather is relatively cool and moisture is high. When consistent warm weather arrives and rainfall becomes sporatic, annual bluegrass will set seed and die. Crabgrass, a warm-season annual, will not germinate until soil temperature reaches 55 F or better.
Confusion often prevails in weed identification and lawn care.
One of the earliest grassy weeds to show up after snowmelt is quackgrass, a cool-season perennial. Typically this weed is misidentified as crabgrass, and an ineffective herbicide is purchased and applied. After reading through this circular, the homeowner should be able to, at least broadly, classify the weeds discussed. Noting the time of year of active growth and whether it is a grass or broadleaved type of weed will help in implementing a control program. While herbicides simplify weed control in lawns, they should not be used as the sole approach.