Sunday, November 1, 2026

Question: What is the oldest and largest botanical garden in Arizona?

Answer: Boyce Thompson Arboretum. Located in Pinal County along U.S. Highway 60 near Superior (about an hour east of Phoenix), Boyce Thompson Arboretum was founded in 1924 by mining magnate and philanthropist Col. William Boyce Thompson. Sitting at an elevation of 2,431 feet at the foot of Picketpost Mountain, it is one of the oldest plant research facilities and botanical institutions west of the Mississippi River. The arboretum spans roughly 372 to 392 total acres, is home to more than 20,000 desert and arid-land plants, and features nearly 5 miles of walking and hiking trails.