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 412 spots.

Photo そらみみ (CC BY-SA 4.0) — via Wikimedia Commons
A flower park on a small island in Hakata Bay, ten minutes by ferry from the city, where nemophila flower with the spring tulips and rapeseed.