The Royal Horticultural Society had made him an honorary fellow in 1946 and in 1986 he became a vice-president. Stearn became a member of the Botanical Society of Britain and Ireland (BSBI) in 1954,[62] joining the Maps Committee the following year to prepare their Atlas of the British Flora (1962).[63][64] He remained on that committee till 1968, when it became the Records Committee.