Mountain Ninebark 'Grey Rock' Enjoy : r iphonewallpapers. Mountain Ninebark 'Grey Rock' (Physocarpus monogynus) is a rugged, handsome native naturally occurring cultivar from the Cache la Poudre Canyon, Colorado. Its peeling, cinnamon brown bark reveals layers beneathhence the name ninebarkand adds texture and winter interest long after its white spring blooms fade. In late spring and early summer, clusters of small, creamy white flowers brighten rocky slopes and dry hillsides, giving way to seed capsules that persist through fall. This hardy shrub thrives in well drained soils and full sun but tolerates partial shade and lean, rocky conditions. Its drought resilience and low maintenance needs make it ideal for waterwise landscapes and native plant gardens. With its natural charm, pollinator friendly blooms, and year round structure, Mountain Ninebark adds authentic mountain beauty and durability to gardens across the Wasatch region and beyond.