Day, a former director and consultant editor at Grower publications, devoted his life to horticulture and as president of the institute launched the publication Come into Horticulture and initiated the James Bruce Lecture.
On leaving school, Day trained at a Somerset Nursery before spending a year as a student gardener at RHS Garden Wisley. He then went on to obtain a degree in horticulture from the University of Reading.
His career saw him working at Suttons of Reading, Blooms of Bressingham, Long Ashton Research Station and the Fisons soil science department.
Day's contribution to the agrochemical industry will also be remembered. He spent 20 years at Pan Britannica Industries - nine as head of the agrochemicals division. During that time he also served on the executive committee of the British Agrochemicals Association.