Acacia koa for up to 25 years. Scarification is needed before "A. koa" seeds will germinate. Koa is endemic to the islands of Hawaii, Molokai, Maui, Lānai, Oahu, and Kauai, where it grows at elevations of . It requires of annual rainfall. Acidic to neutral soils (pH of 4-7.4) that are either an Inceptisol derived from volcanic ash or a well-drained histosol are preferred. Its ability to fix nitrogen allows it to grow in very young volcanic soils. Koa and ōhia lehua ("Metrosideros polymorpha") dominate the canopy of mixed mesic forests. It is also common in wet forests. The koa's trunk was
Koa Kannon no graves and thus no patrons under the danka system except for the surviving family of the seven war criminals. Koa Kannon is always requesting general help since the only thing maintaining the temple is offering money from visitors, volunteers, and members of support groups. One such association is the Koa Kannon Support Group, which was founded in 1942 by its first president Iwane Matsui and is preserved primarily by local devotees in Atami. There was in addition the Society to Protect the Koa Kannon which was established in 1994, but due to a scandal involving some of its board