R. 'Irresistible Impulse'Created by the late Harold Greer by crossing 'Mars' with 'Purple Splendor', this unique rhododendron has very purple flowers coming out in late May. The plant always attracts attention for the purple lovers. Growing to 5 ft tall and wide in 10 years, it has large trusses of deep red purple that completely cover this attractive plant. Each flower has a large, deep purple blotch on the uppper lobe. It flowers very young, often on a one year old plant.