Crater LakeThis incredible upright rhododendron with its clusters of ruffle edged blue flowers make an immediate statement in any garden. While the blue trusses make this plant stand out, the hints of lavender add a dazzling color complexity. We love Crater Lake, both the park and the plant! Crater Lake typically blooms around April and grow in partial shade to full sun. It can grow to 5' tall at maturity. Hardy to 5F when protected against windchill.