Crabgrass is very often incorrectly identified. Crabgrass is an annual plant; it comes up from seed every spring. It develops into an aggressive spreading plant in June through July. Very often people confuse crabgrass with other perennial grasses. These grasses are present in lawns year-round. The majority of perennial grasses can not be selectively controlled.
An Ounce of Prevention
Once established, it is very difficult to remove without harming desirable grasses. Get a jump on stopping crabgrass by applying Zamzows Defendz Crabgrass Preventer. This chemical burns up the tender young sprouts of crabgrass. The key to success is timing. If you apply crabgrass preventer too early, the chemical breaks down and allows some late seed to germinate. If applied too late, the stronger young plants will survive the pressure of the herbicide and develop into full-size crabgrass. Mother Nature is the best guide for the timing of the application. When the forsythia bush blooms - the bright yellow flowering shrub - that tells you that the soil temperatures are warming and you are early enough to apply crabgrass preventer.
Worth a Pound of Cure
Often soil temperatures vary in yards based on sunny areas versus shade. You need protection over a three month period. In lawns where crabgrass was a severe problem the prior year, it is strongly advised to apply crabgrass preventer twice, 60 to 70 days apart. Once established, there are controls for mature crabgrass, but they are only about 70% effective and require several applications with strict temperature range restrictions for an application.