A loose soil rich in well-composted organic matter is ideal, and good drainage is a must. If drainage is a problem, a raised bed 8 to 12 inches above ground level is recommended. During hot periods, flowers will last longer on plants in filtered shade than on those in full sun. Partial shade also helps to reduce cold injuries in winter. Rhododendrons planted under shallow-rooted trees, such as elms and maples, suffer from competition for water and nutrients.
Planting Dig the planting hole two times wider than the root ball and the same depth.
Wider planting holes encourage the roots to grow into the native soil so that the plant will establish itself quicker. Place the plant so that the top of the root ball is level with the soil surface, then backfill with native soil removed from the hole. As you replace the soil, break up heavy clods and remove stones and debris. Do not fertilize the plants now. Wait until they are established.