Thanks for writing. Oriential lilies do best in moist, well-drained soil that's rich in organic matter. They'll also do fine in sandy soil. But if your soil is thick, heavy clay, it's best to amend it with lots of compost, coir, peat, or another form of organic matter before planting.
Oriental lilies are not ericaceous --- this term refers to plants in the rhododendron family (azalea, rhododendron, mountain laurel, blueberry, etc.). Lilies are not closely related to these plants.
---Justin, Senior Garden Editor, BHG.com