Rhododendron subg. Tsutsuji
All azaleas and rhododendrons are classed as Rhododendron but the name "azalea" is commonly used for native deciduous species and some evergreen Asian types.
Native to Japan
Add plenty of leaf mold, peat moss, or bark can help create the ideal environment. This is particularly important if you're placing the plants near your home's foundation, where lime can leach out of the concrete and neutralize acid soils. Limestone gravel used for drainage around your home can also cause soil to be too alkaline. When choosing the best spot to plant, take the sun into account. Azaleas like plenty of morning light. However, avoid areas that get midday or hot afternoon sun--plants in full sun are susceptible to lacebugs and spider mites.