The Hanami Festivals in Japan are a tradition that stretches back a thousand years, celebrating the beauty of the blooming cherry trees that are virtually everywhere in the country. All over Japan these festivals take place, so no matter where you happen to be in the country you can enjoy it in one form or another. The biggest festivals generally occur from March to May, though some locations experience their blooms as early as January and as late as June. The biggest time of the year is known as Golden Week and takes place from April 27 to May 6.
Though the celebrations are rooted in a long-standing tradition, what they really boil down to is an excuse for the Japanese people (and a great many tourists) to party. Drinking, BBQs and picnics in the park are common, often accompanied by other forms of entertainment. These celebrations can sometimes go very 
late into the night, the blooming trees being illuminated with lights after dark.
For the tourists, merchants are out in abundance, selling food, souvenirs and crafts. The food and other variety of goods are dependent upon whatever region one happens to be in, so every festival is different in its own right and represents the traditions of a particular area of the country. During the blossoms, television shows follow their progress almost religiously, letting people know when and where the next round of blooms will occur.
The biggest problem for those who might wish to go and see the blooms is that during peak times everything in the country gets expensive. Air fare and hotel prices go through the roof and wherever the blooms happen to be gets pretty crowded. Competition for “prime space” can be pretty hectic if you want to set up and relax, so it’s often easier to simply wander and view the trees throughout a particular area.
For the biggest parties, such as during Golden Week, one should plan to spend a bit of cash. For those that prefer something smaller, they should consider going to a smaller location instead of someplace huge like Tokyo. Also, it helps to go either during the beginning of the blooms or near their tail end. And finally, for those that don’t wish to leave their home country at all, Hanami has spread to many cities in the US, so it’s often not difficult to find someplace nearby to enjoy this beautiful party more frugally.