This persistent perennial weed is a serious problem in the South and Southwest. The roots may penetrate 3 to 6 feet into loose, rich soil. The stems grow 1 to 6 feet tall and frequently root at lower nodes, forming dense clusters that crowd out desirable plants. The leaves grow 1 to 2 feet long and 1 inch wide. Hairy purple seedheads, up to 16 inches long, appear on the ends of the stems from June to October. The seeds germinate in the spring. Johnsongrass is found along roadways and in fields, lawns, landscaped beds, and unplanted areas.
Johnsongrass is difficult to control because of its extensive rhizomes. Hand-pulling established plants is not a practical solution because new plants will sprout from any rhizomes left in the soil. Digging young clumps is successful, so watch for seedlings and control early.