Koa trees in lower puna

[Mitzi M]

Limiting factors for koa include rainfall and soil depth. I think anywhere in Puna the rainfall is fine, but in lower Puna the soil depth will probably be an issue. While I've also been told that koa once grew (and can do well) down to almost sea level in other places, a botanist friend told me that they have never grown below around 1500'- 1800' on Kilauea because the "soil" is simply too new and not deep enough. That said, I also have 4 strapping young koa seedlings that I started from a fairly close source (a tree in Mountain View). My plan is to try them in big holes I fill with as much soil/compost/cinder as I can possibly find. I don't think they will grow to their full glorious size this way, but will probably stay smaller (and more manageable) in a backyard. They shoot up very fast in the first 5-7 years, growing 5 feet or more per year. Then they slow down some. At this point, they could be pruned conservatively to keep them smaller and compact. Don't plant them anywhere near foundations, roads, sidewalks or driveways, as their roots are notorious for heaving pavement. You might want to keep them away from structures as well, because if they do get tall, they can drop some mighty big branches. Koas are legumes and fix nitrogen in the soil, so you can have free fertilizer for what you plant underneath them. I think they are beautiful trees, and in the right spot, can be great additions to the landscape. It will be interesting to keep sharing info about the progress of lower Puna koas. Good luck!

Aloha,
Mitzi

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