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 黒崎一男 (CC BY-SA 4.0) — via Wikimedia Commons
About 3,000 roses of some 850 kinds in Nakano, northern Nagano, with a rose festival in early summer (entry 500 yen during the festival).