Abstract. Volcanic rock has been used for decades as a horticultural substrate worldwide.In Spain, the use of this material as a substrate is ancient; it was initially used in theCanary Islands because of its volcanic geological origin. At the University of Almerı´a(Almerı´a, Spain), three independent vegetable crops were grown under greenhouseconditions: sweet pepper, tomato, and melon. The volcanic rock came from a location inthe geographic center of Spain, which facilitated logistics. Bags of volcanic rock (25 L)were used and were compared with a commercial coconut fiber substrate of an equalvolume. All physical, physical–chemical, and chemical parameters of the volcanic rockwere determined using European standard analytical procedures. Fertigation was applied,independently adapted to the physical, physical–chemical, and chemical characteristicsof each substrate. The cultures were performed under a randomized complete blockexperimental design. Fertigation parameters, pollutant emissions, fruit production, andthe quality of each culture were measured. The results showed that the assessedparameters of the volcanic rock substrate are not a limiting factor for its use asa horticultural substrate. The resultant production and quality were very similar amongthe three crops compared with a widely used commercial control. Therefore, volcanicrock emerges as a local, sustainable alternative to be used for soilless crop cultivation