Cherry blossom is three weeks of it. Flip through the other forty-nine — and watch what's in bloom move up and down the country.
The calendar is the way in. Underneath it sits the ordinary thing — search, filter by month or flower, and open any of the 444 spots.

Photo pakku (CC BY 3.0) — via Wikimedia Commons
In Okinawa the sunflowers come in winter. About 200,000 of them fill some 22,000 square metres of farmland in the Atta district, and the sunflower festival usually runs from mid February into early March.