Quackgrass is characterized by light green to blue-green coarse blades that are rough on their upper surface. If not mowed, it can grow 5 feet or more in a single season.

Narrow flower spikes rising from the plant resemble rye or wheat. The plant spreads by large, white rhizomes.

Quackgrass grows quickly in spring and fall. It is especially vigorous in thin, undernourished turf. Though it sometimes goes unnoticed in early spring, quackgrass becomes quite obvious as it turns brown in summer.