Every year, Washington celebrates the arrival of spring with a two-week Cherry Blossom Festival. More than 1.5 million people from around the world visit the nation’s capital during the festival. They all hope to see the cherry trees at their “peak bloom.” Park officials define "peak bloom" as the period when 70 percent of Washington’s most common cherry tree variety -- the Yoshino trees -- are blooming. Yoshino cherry trees are one of 12 types of cherry trees in Washington. Peak bloom lasts several days each year.