Rhododendrons should be planted in a porous, well drained acid soil (pH 4.5 to 6). Organic material should make up at least 25%-50% of the soil. This includes any natural material as decayed leaves, compost, pine needles, sawdust, peat moss, rotted or processed manure and shredded wood/bark (salt free). Work into the soil to a depth of at least 15”-24”. Also add sand and gypsum to heavy clay soil to improve drainage and reduce compaction. Add humus to sandy soil for moisture retention and nutrient-holding capacity. You must provide a comparable interface between the root ball and the surrounding soil, which will facilitate water movement between the two.