Pennsylvaia smartweed, also called pinkweed, is a summer annual with small, bright pink flowers that form along spikelike clusters from July to October. It has smooth stems that appear reddish purple and can grow up to 4 feet in height. Smartweed prefers moist soil and spreads by seed, causing an infestation in disturbed areas.
Good drainage and low mowing can help to prevent smartweed from establishing on the property. Applying a pre-emergent herbicide in the spring is another way to combat this annual weed. If it has already established on the property, a postemergent herbicide containing clopyralid or triclopyr is an effective solution to providing quick knockdown and control.