Fullerton Arboretum was founded in 1979 on the campus of the California State University, Fullerton in North Orange County as a joint project between the California State University system and the City of Fullerton Redevelopment Agency. The Arboretum was designed to occupy the land that once held the remnants of the Gilman Ranch, the first commercial orange grove in the area. In 1875, Richard H. Gilman planted an orange grove with Valencia oranges and named his farm the Semi-Tropic Fruit Ranch. Other farmers followed suit and planted the winter ripening Washington navels, which gave Orange County a year-round citrus industry and started what some called “California’s Second Gold Rush.”
By 1979, the majority of the orange trees that once made up the Semi-Tropic Fruit Ranch were gone and today’s collection only contains the 8 original healthy trees left from Gilman’s grove and an additional 40 that have been planted since the Arboretum opened, representing 15 varieties.
The collection is arranged in two different gardens with two different designs. Behind a historical home at Fullerton, a Victorian garden grows one of the original trees from the Gilman ranch. The citrus orchard surrounds this garden and is laid out much like any commercial orchard with trees planted 18 feet on center in rows that are 20 feet apart. The orchard contains the orange varieties that early Orange County farmers sent to Eastern markets including Citrus sinensis ‘Valencia’ grafted onto the Olinda budwood. These trees were budded from the original tree in Olinda (less than five miles from the Arboretum), which was the source of budwood for much of the Orange County citrus industry from the late1800s to the 1950s. The Arboretum’s other citrus trees are located in the Rare Fruit Garden. These trees are arranged less formally and surround the Arboretum’s Orchard lawn. The specimens in this area are less commonly known to the citrus industry and consumers today but provide examples of interesting and somewhat exotic fruits used in other parts of the world.
In keeping with the Arboretum’s mission to promote botanical and historical education, we tell the story of Orange County’s rich agricultural history through our Heritage House and our orchard. Through the Citrus Collection, we emphasize the historical, agricultural, and economic impact of the citrus industry on our region from 1840, when the first citrus tree arrived in the area, to 1940, when 68,000 acres of Orange County were planted with citrus to today, when farmers have become land developers and replaced their orchards with homes and shopping malls. As we add new varieties to our Citrus Collection, we want to demonstrate to visitors that the newer varieties are not as thirsty as earlier ones, are smaller in size and more suited for smaller lots, and yet still produce large, juicy edible fruit. Because we felt that preserving the Citrus Collection was a priority for us and for the Orange County community, Fullerton Arboretum applied to the Plant Collections Network for its designation as an accredited collection. The Arboretum was accepted into the program in 2000.