The official nickname for Portland Oregon is the city of Roses or Rose City. In 1889, the Portland Rose Society was founded, and promoted the planting of 20 miles of Portland's streets with roses in advance of the 1905 Lewis and Clark Centennial Exposition.
One of the major attractions in Portland is also the International Rose Gardens which is where you will find over 10,000 rose bushes of approximately 650 varieties.
About 100 years ago a citizen convinced the local government to set up a rose test garden during World War I to preserve the species of European roses that might be lost during the bombings. The International Rose Test Garden was started in 1917, officially. It is the longest continuously operated public rose test garden in the United States.
If you are ever in Portland you must visit. It is amazing and the best month to visit is June when everything is blooming, however it is amazing all summer and it is free.