The Fullerton Arboretum is open every day of the year except New Years Day, Christmas Day and Thanksgiving Day---and for occasional special events. The grounds are open from 8:00 a.m. to 4:30 p.m. each day. Admission is generally free except during occasional special events. . There is not a charge for visitors, however to help support the development of the Arboretum gardens and educational programs, voluntary donations at the main entrance are encouraged.

Special extended visiting hours (on the grounds only) are planned for the summer months. During July, the Arboretum will close at 8:00 p.m., August 7:30 p.m. and September 7:00 p.m. Check the website before making a special visit to confirm the hours of operation on the day you wish to visit. Note: Normal office hours are 8:30 a.m. to 4:30 p.m. Monday through Friday. Offices are closed on weekends and holidays.