Need chemicals for crabgrass control?

The answer is, No. While the best way to kill crabgrass is with preemergent herbicides, the best way to control it is by having a healthy lawn. Here are some ways to promote lawn health -- at the expense of crabgrass:

• Fertilize (compost is fine) more heavily in autumn than spring. By autumn, frosts will have already killed any crabgrass.
• Don't let bare spots remain uncovered for long, else opportunistic crabgrass will take root. In the fall, fill in those bare spots by overseeding.
• When irrigating the lawn, water more deeply and less frequently. Crabgrass is a notoriously shallow weed.
• Mow "high", leaving the lawn grass at a height of 2 1/2"-3". This will allow the lawn grass to "protect its own turf" better, depriving crabgrass seeds of the light they need to germinate.