New rose cultivars are continually sent to the garden from many parts of the world and are evaluated on several characteristics, including disease resistance, bloom form, color and fragrance. It is the oldest continuously operating public rose test garden in the United States and exemplifies Portland's nickname, "City of Roses". The garden draws an estimated 700,000 visitors annually.
In 1915 Jesse A. Currey, president of Portland's Rose Society and Sunday editor of the Oregon Journal, convinced city officials to institute a rose test garden to serve as a safe haven during World War I for hybrid roses grown in Europe. Rose lovers feared that these unique plants would be destroyed in the bombings. The Park Bureau approved the idea in 1917 and by early 1918, hybridists from England began to send roses.
The International Rose Test Garden covers 4.5 acres (18,000 m2) in several tiers facing downtown Portland, the Willamette River, and East Portland. On clear days, there are views of the Cascade Range, with Mount Hood featured prominently.
The Rose Garden Store opened May 1, 2000. The store sells rose-themed books, merchandise, and garden supplies.
The garden includes an amphitheater designed with the original garden. It hosts many events throughout the year, predominantly classical music concerts and a few plays. During good weather, the amphitheater is popular for picnicking and flying disc games.