You might mean quack grass, which is a perennial. Crab grass is an annual, though it can be very persistent in reseeding every year if allowed to mature. Quack grass multiplies with roots, and is difficult to eradicate. Options: till and pull out plant and root, or spray it with Round-Up. Then, weekly if not more often, weed the garden to prevent encroachment from surrounding quack-grass-infested areas.