At the Rokko Alpine Botanical Garden (六甲高山植物園), operated by Rokkosan Kanko Co., Ltd. (headquartered in Nada Ward, Kobe), the Shichidanka (シチダンカ) — once known as the "phantom hydrangea" — is now at peak bloom.
The Shichidanka is a variety of Yama-Ajisai (山アジサイ), distinguished by its decorative petals that develop into double blossoms. Its sepals, numbering more than ten, overlap in a star-shaped formation. In addition to the Shichidanka, the limited-time Hydrangea Garden features a diverse selection of hydrangea varieties.
The hydrangeas of the Rokko mountain range take on a beautiful shade known as "Rokko Blue," influenced by the acidic, granite-based soil and the area's humid climate.
About the Shichidanka (Hortensia serrate var.serrata f.prolifera)
A deciduous shrub growing to a height of 1 to 1.5 meters. The Shichidanka was documented in Siebold's Flora Japonica during the Edo period, but was not found again for many years, leaving its existence in doubt. In 1959, it was unexpectedly rediscovered on Mount Rokko. Cuttings were then propagated, and plants have since spread to various locations across Japan. The bloom is expected to continue through approximately mid-July.
Event: Rokko Alpine Botanical Garden × Koyomi Seikatsu / Hanabiyori
An exhibition pairing the 72 seasonal micro-seasons (七十二候) of the traditional Japanese calendar with flower colors, alongside a flower-collecting stamp rally. Visitors can enjoy the blooms of alpine plants from the Alps, the Himalayas, and Japan's mountains while spending time appreciating each season.
Dates: Through July 12, 2026 (Sunday)
Hours: 10:00 AM – 5:00 PM (Ticket sales end at 4:30 PM)
Participation fee: Free (garden admission required separately)
Garden Information
Open season: Through November 29, 2026 (Sunday) — closed on some days; check the official website for details
Hours: 10:00 AM – 5:00 PM (Ticket sales end at 4:30 PM)
Admission: Adults (junior high school students and above): ¥900 / Children (ages 4 to elementary school): ¥450
Parking fee: ¥1,000
Note: Events and hours are subject to change or cancellation due to inclement weather.
