Experiments conducted for two consecutive years indicated that barnyardgrass, large crabgrass, and giant foxtail interfered with the growth and development of container-grown ‘Gold Drop’ bush cinquefoil. Grass weed densities ranging from one to six weeds per container reduced Gold Drop bush cinquefoil growth. Bush cinquefoil shoot dry weight, averaged over all grass weeds, was decreased as much as 75% after 83 days of interference. The reduction of cinquefoil growth was independent of the number of grass weeds in the container.