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 KCyamazaki (CC BY-SA 4.0) — via Wikimedia Commons
One of Tokyo's oldest daimyo gardens, laid out in the 17th century, where red spider lilies come up among the paths and ponds in September. Entry 300 yen.