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 Hiroaki Kaneko (CC BY-SA 3.0) — via Wikimedia Commons
A lakeside park on Lake Kawaguchi with about 80,000 lavender plants, most of the lavender around the lake, with Mount Fuji across the water. A venue of the Kawaguchiko Herb Festival in some years; free.