| 1 | | | Brooklyn Botanic Garden (USA) |
| 2 | | | Crystal Springs Rhododendron Garden (USA) |
| 3 | | | Descanso Gardens (USA) |
| 4 | | | Jenkins Arboretum (USA) |
| 5 | | * | Rhododendron Species Botanical Garden (USA) |
| 6 | | | San Francisco Botanical Garden (USA) |
| 7 | | | Tyler Arboretum (USA) |
| 8 | | | UBC Botanical Garden (Canada) |
| 9 | | | Washington Park Arboretum (USA) |
