Smooth Crabgrass is a summer annual grass that is also known as Small Crabgrass or by its scientific name, Digitaria ischaemum. Due to its horizontal growth habit, look and inability to be controlled, it\'s often considered a problematic lawn weed in yards where it wasn\'t planted.
Smooth Crabgrass can be identified as a low-growing annual grass—or lawn weed—that lies low in your yard and roots at the lower nodes. Its ligule is tall and rounded, and its collar is broad and sparsely hairy. It has sheaths that are compressed, smooth and generally tinged purple in color. The blades are sparsely hairy near the ligule, sharp and pointed. Smooth Crabgrass spreads by seeds in bunch formations and has a light yellowish-green appearance, setting this grassy weed apart from many types of desired grass.
As a grassy weed, Smooth Crabgrass invades lawns and landscaping, taking over areas where desirable types of grass should grow, replacing them with lawn weeds instead. Smooth Crabgrass can be found throughout most of North America. These grassy weeds are also summer annuals, meaning they begin to grow (germinate) in the spring, mature in the summer, and then produce seeds and die by the fall or first hard frost—an entire life cycle completed within 12 months.
Smooth Crabgrass can be extremely difficult to manage using cultural methods such as hand-pulling lawn weeds or proper watering and fertilization routines. This grassy weed has a horizontal growth habit that allows it to escape most conventional mowing heights—although higher lawn-mowing heights can allow for a more competitive lawn. Of course, higher mowing heights are not always aesthetically pleasing in home lawns and landscaping. For effective weed removal, professionally selected and applied weed control treatments are your best bet for eradication.