In the original plan, completed in 2001, many ideas were embraced with significant progress made toward their fruition, whereas others were deemed not feasible due to horticultural conditions, institutional priorities, or excessive cost. An effort was initiated in 2015 to document progress made to date and revisit goals based on current understandings of site conditions and institutional priorities.
Significant changes to the plan include:
- Development of a horticultural West Side Entry collection in place of an expanded Oleaceae collection due to emerald ash borer.
- Expansion of Flowering Trees Collection to include genera such as Styrax and Koelreuteria to extend flowering time.
- Scope reduction in Magnoliidae collection to focus on Magnolia. Development of Magnolia collection to continue on the East Side, as opposed to the West Side.
- Thuja collection to be retained on the West Side.
- Rosaceae collection to change in scope, focusing on species of economic importance or exhibiting superior performance.
- Scope change in Pinetum to become a horticultural collection focusing on botanical species and cultivars recommended for planting in the Midwest.
- Diversity collection to be dissolved, with this area instead used to exhibit trees and shrubs of conservation concern.
- Saxifragaceae collection to be dissolved instead of expanded.
- Establishment of a List of Priority Genera, consisting of the Arboretum’s six nationally accredited collections (Acer, Magnolia, Malus, Tilia, Quercus, Ulmus) and genera of interest (Aesculus, Amelanchier, Carya, Crataegus, Fagus, Juglans).