Feraferia never had many members. What it had was a founder with a full cosmology and the discipline to publish it. Fred Adams dated his own religious turn to 1956, when he became certain of the primacy of the Goddess; by 1957 he had founded a smaller fellowship, the Fellowship of Hesperides, and by 1959 he was running a multi-family intentional community in Sierra Madre, California. Feraferia itself took its public name and its newspaper in 1967.
The name is a coinage from Latin, fera for wild and feria for festival, and it says what the religion was for. Adams wanted a nature religion built from Greek and Minoan imagery rather than Northern European sources, oriented around the wheel of the agricultural year and a divine feminine principle he treated as primary. He summarized the whole project as uniting ecology, artistry, mythology and liturgy, a phrase that reads as a manifesto because it was meant as one.
Numbers were never Feraferia's strength. What it had instead was a founder whose writing and personal charisma reached far past his own small circle, so that a fellowship most of the wider Pagan movement never formally joined still shaped how that movement thought about nature religion. Adams died in 2008, and organized activity under the Feraferia name has been minimal since; the writings remain, and later Pagan environmentalism still shows their fingerprints.