Crab grass is a common weed that is familiar to most California homeowners. Crab grass is an annual plant that propagates through small seeds from mature plants. Interrupting this life cycle may be the best defense in getting rid of the pest. There are two methods for controlling crab grass: cultural control and herbicide applications. According to the University of California, a healthy lawn will not require the use of herbicides for weed control as a thick and lush turf will crowd any weed from the lawn.
Mow the lawn to the correct height for that particular grass species. Grass lawns that are mowed regularly increase the vigor of the plants. The turf grass shades other weed species seeds from germination. Consult your local California county extension service agent for information about your grass species.
Irrigate the lawn on a weekly basis. Daily watering of the lawn encourages shallow roots to the grass which in turn makes for a weaker plant. The weaker plants will not shade out other weed seeds from germination.
Fertilize the lawn turf when it is actively growing. Correct application of lawn fertilizer will aid in denying weed seeds a chance for germination in a thick turf grass.
Apply an herbicide only as a last resort when all other methods fail. In this type of case it may be best to start over. Kill the existing lawn grass due to a heavy weed infestation. Reseed the lawn area with a grass species conducive to a thick lawn with your particular light and soil requirements.