Catawbiense Grandiflorum Rhododendron Catawbiense Grandiflorum Rhododendron is a must for the serious landscaper. The lilac blue flowers are long lasting. The plant is vigorous and showy. Excellent background plant. Primary Color: Blue Bloom Time: Late Height in 10 Years: 6' Hardiness (Temperature): -15 Sun / Shade: Morning Sun, Afternoon Shade Landscape Category: Shrub Genus: Rhododendron More plants in: Hybrid Rhododendrons Find out if this plant is available: Rhododendron and Azalea Availability List