Crabgrass is a warm-season, annual grass, which grows best in the heat of mid-summer. It overwinters as seed, comes up about mid-May or later, and is later killed by fall frosts. Crabgrass is not shade tolerant, and grows best in full, hot sun.
There is currently no herbacide available for existing crabgrass, Superior Spray Service does however apply a post-emergent to aid in the control of crabgrass. Wetting existing crabgrass and applying baking soda to the grass will kill it but you will have to experiment to get the correct mixture.