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
Wahiawa Botanical Garden The property was transferred to Honolulu in 1950, and opened as a botanical garden in 1957. It is open seven days a week, from 9am to 4 pm. The Garden's collections include: Blue Ginger ("Dichorisandra thyrsiflora"), Hāpuu ii ("Cibotium chamissoi"), Koa ("Acacia koa"), Blue Jacaranda ("Jacaranda mimosifolia"), "Nageia nagi", "Angiopteris evecta", Shaving Brush Tree ("Pseudobombax ellipticum"), Autograph Tree ("Clusia rosea"), Nutmeg ("Myristica fragrans"), Allspice ("Pimenta dioica"), Travellers' Palm ("Ravenala madagascariensis"), "Chrysophyllum oliviforme", Common Screwpine ("Pandanus utilis"), "Parkia javanica", Guanacaste ("Enterolobium cyclocarpum"), Candle Tree ("Parmentiera cereifera"), Elephant Apple ("Dillenia indica"), Moreton Bay Fig ("Ficus macrophylla"), Queensland Kauri ("Agathis robusta"), "Brownea macrophylla",