The best places to plant rhododendrons are locations that feature fairly acidic soils that are rich in organic matter and provide excellent drainage. Rhododendrons also prefer shaded locations that are sheltered from the wind.
The best place to plant a rhododendron is on the north or east side of a home. They receive protection from direct afternoon sunlight in these locations. Rhododendrons grow best when they are planted close to buildings or other windbreaks, which is why they are so often used as foundation plantings. They should never be planted on the south side of a building unless significant shade is cast by nearby trees.
Soil quality is a very important factor in determining planting sites for rhododendrons. Never plant them in sandy or clay soils. As understory plants in conifer-dominated woodlands, rhododendrons grow best in locations that mimic that environment.