Don't want to miss cherry blossom viewing this year? Then please plan your traveling dates between late March and mid April.
The blooming period for cherry blossoms is about 5-12 days and travels south to north across the Japan archipelago. To track the first date of the blooming season, please check the following site for updates:
2011 Japan Cherry Blossom Forecast
Even if you miss the time, don't be disappointed. Thanks to extended routes of bullet train, it'll be much easier to reach Aomori prefecture, northernmost part of Japanese mainland, where you can enjoy cherry blossoms as late as early May. Hirosaki Castle located in northwest part of Aomori Prefecture is known for its magnificent view with 2,600 cherry trees. The castle celebrates its 400 year anniversary in 2011 and there will be a variety of events going on including its cherry blossom festival from late April to the beginning of May.
Cherry Blossom Viewing (Ohanami) doesn't mean just "viewing" blossoms but to have fun with friends and families. Bring your own sake and try mingling with Japanese locals having a party under the cherry blossoms in full bloom!
For your reference, here's the date of the first bloom in 2010 and regions famous for cherry blossoms:
Also, please check out more cherry blossom spots in Japan: