The city of Portland, Oregon is ideal for growing roses outdoors due to its location within the marine west coast climate region, its warm, dry summers and rainy but mild winters, and its heavy clay soils. Portland has been known as the "City of Roses", or "Rose City", since 1888, after Madame Caroline Testout, a large pink variety of hybrid tea rose bred in France, was introduced to the city. Thousands of rose bushes were planted, eventually lining 20 miles (32 km) of Portland's streets in preparation for the Lewis and Clark Centennial Exposition in 1905. The Rose City Park neighborhood in northeast Portland was formed in 1907, the same year of the first annual Portland Rose Festival. During World War I, nursery owners in Portland began planning a large rose garden to protect European rose species from the war. The garden was established in Washington Park as the International Rose Test Garden in 1917. Today, the Portland Rose Festival occurs each June with a carnival, parades, and navy ships docked along the Tom McCall Waterfront Park to promote the city. The International Rose Test Garden is currently one of the oldest public rose test gardens in the United States, covering 4.5 acres (1.8 ha) with over 8,000 rose plants and more than 550 different species. In 2003, Portland adopted the "City of Roses" as its official nickname.