Hakusan Jinja (白山神社) is a Shinto shrine which is a 1-minute walk from Toei Mita Line Hakusan Station, or a 5-minute walk from Tokyo Metro Namboku Line Honkomagome Station. Though not so large a temple, many hydrangeas a planted in the precincts, and they bloom in mid-June. For details about this shrine, see the article on Hakusan Shrine.During this period, the Ajisai Matsuri is held here.
Ajisai Matsuri at Hakusan Shrine
During the hydrangea blossom season, the Ajisai Matsuri (あじさいまつり), or the Hydrangea Festival, is held at Hakusan Jinja.
A fuji-zuka is a mound which were created in a Shinto shrine to resemble Mt. Fuji, often with rocks from Mt. Fuji. When the worship to Mt. Fuji was popular around the city of Edo and its successor Tokyo, many fuji-zuka were built claiming that if you climb a fuji-zuka, there will be the same benefit as climbing Mt. Fuji far away. At this shrine, many hydrangeas are planeted on the mound, and you can climb the fuji-zuka only during the Ajisai Matsuri.
Stalls by locals are open on weekends.
Ajisai Fuji, not to be comfused as aforementioned Fuji-zuka, is a pile of hydrangea flowers. This is made once in several years and not every year.
Note that even after the end of the Ajisai Matsuri, you can enjoy the flowers for several days, but then they will be cut off.
Many stage events and such are held on weekends during the festival.