The Four Season Garden, initially known as the Forecourt Garden, is located in front of the Thornhill Education Center. As its name suggests, the Four Season Garden contains more than 70 kinds of plants that inspire year-round interest. Planted in 1994, the opening of this 2,000 square foot garden coincided with the reopening of the Thornhill Education Center after a three-year rehabilitation project. The garden's outer beds showcase perennials and shrubs that demonstrate beauty throughout the year, and the small circular bed in the center displays seasonal plantings. More than just an aesthetic feature, the Four Season Garden was intended to supplement the center's courses on residential landscaping and plant selection.
The Morton Arboretum's 1995 Annual Report stated:
The Forecourt Garden and landscape at the Thornhill Education Center now includes some of the hardiest and most beautiful woody ornamentals, combined with unusual perennial grasses and annuals. The site provides horticulture students, homeowners and landscape professionals with a rich source of information about ornamental plants.