Ericaceous bed Wikipedia
An Ericaceous bed is a bed (or garden) with acidic and often nutrient-poor soil such as Ericaceous compost and different types of peat. The pH of the soil is typically between 4.5 and 6. The purpose is typically to grow a number of garden plants which require (or thrives best in) acidic soil. Such plants commonly include heathers (Erica, Calluna and more) and Rhododendrons. Another group of plants common in ericaceous beds are those belonging to the boreal coniferous forest, e.g. Vacciniums. A number of orchids also grow well in nutrient-poor soil.