[2] In 1931, Avery was brought on as professor of botany at Connecticut College.
Avery left Connecticut to head the Brooklyn Botanic Garden (BBG) in 1944.
Under his direction, the BBG underwent several expansion projects as it acquired more land.
In 1948, he hired Frank Okamura to help him take care of several bonsai housed at the garden, which were gifted by Ernest F. Coe in 1925.
Avery began to work on a handbook for the care on bonsai with the help of horticulturalist Kanichiro Yashiroda, entitled Handbook on Dwarfed Potted Trees - The Bonsai of Japan.