- 1867 – Original campus master plan placed the Arboretum north of Green Street where the College of Engineering currently exists.
- 1900s – the site moved to south campus, located near Smith Music Hall. A rock garden was added in 1916 and abandoned in 1951. A lily pond was created near the same area in 1923.
- 1980 – Another Campus Master Plan was drafted
- 1990 – University of Illinois approved a 160-acre Arboretum site bounded by Florida Avenue on the north, Lincoln Avenue on the west, Windsor Road on the south, and Orchard Downs on the east.
- 1991 – Chancellor Weir entrusted the Miles C. Hartley bequest of $970,000 to establish the All-America Selection Trials Garden—the central point of Arboretum development.
- 1994 – the Miles C. Hartley Garden was dedicated
- 1996 – Richard and Rosann Noel funded construction of the Noel Welcome Garden
- 1997 – nearly $600,000 from the Illinois Land Improvement Contractors Association to dig the three ponds. Donors included Birkey’s Construction Equipment, Capitol Machinery, Champaign Asphalt Co., Kuntz Equipment Co., Roland Machinery, Co., and GROWMARK.
- 2008 – The Sen Cherry Tree Alleé was made possible by gifts from Dr. Genshitsue Sen and Dr. and Mrs. Luting Liao
- 2010 – The Hosta Garden plan developed and planted in 2011 by the Illinois Prairie Hosta Society
- 2011 – The Frank W. Kari Walkway, given in Dr. Kari’s memory by his family
- 2013 – 12 black metal benches lining the Linden Allée were donated by the Romweber and Santogrossi families
- 2014 – the Azumaya gazebo was donated by Nick Offerman in honor of Shozo Sato
- 2017 – the Sesquicentennial Garden was installed in celebration of the University of Illinois’ 150 anniversary, donation by Jo Downey
- 2019 – the Council Ring was installed, Zan’s Bench installed, Golden Grove planted
- 2020 – sidewalk connecting Zan’s Bench to the Pond Walk, bench and concrete pad added in the Golden Grove
- 2021 – Zan’s Garden, the seawall, Hosta Garden boardwalk, sidewalk from Azumaya to boardwalk