Saturday, September 13, 2008

Planting Koa

For those who live in Hawaii and are interested in helping restore the native forest, as well as work to reduce one's carbon footprint, there's hardly anything better one could do than plant Koa.

Koa is a wonderful tree, producing one of the worlds finest furniture woods, growing to large sizes with attractive canopies. Surprisingly, it is also a near ideal agro-forestry tree, growing very rapidly and with strong nitro-fixing properties(actually, it's a fungus that grows on the koa roots that is the nitrogen fixer.) It is strong and a robust grower, as long as it isn't planted in heavy stands or in a monoculture environment, for then it seems to become prone to root knot nematode trouble.

Propagating Koa is easy: gather a mixture of seeds in after the pods have recently fallen along side trails and road cuts(illegal without a permit, of course) Sort the seeds as the lightweight ones are often aflicted with a burrowing larva that makes the seeds non-viable. The big plump seeds will sprout easier produce better trees, so for your own little stand it's worth searching them out.

The seeds themselves have a very strong seed coat, and germination will take a very long time if this seed coat isn't "scarified" or nicked to barely barely expose the embryo. I do this with a nail clipper, and it seems to be about the best trick.

Planted in peat pots the trees will germinate and sprout in under a week. Keep the pots in partial shade as this seems to encourage a more robust sprout.

Do NOT plant the koa in pots. Plant the seedling directly outdoors as soon as the roots start to break the peat pots. The reason for this is that Koa can rapidly become root bound in a pot, and I find it near impossible to outplant after this occurs. A root bound koa will never flourish.

Plant the Koa in areas sheltered by other light vegitation, and attend after a few weeks. Once the root structure has been well established, it's best to cut back the surrouding vegitation to expose the tree to full sun. THEN she'll really take off. You can expect a koa tree to add 5 feet of height a year and about 1.5 inches of trunk through the life of the plant. They get big in a hurry, so give them room to grow. This one in the picture is 4 feet tall and was planted in January.

How can you lose?


Kurt said...

It's scientific name is Acacia Koa. Where did you get the seeds?

jaywfitz said...

There are two types of koa on the island A. Koa and A. koaia which look a lot alike unless you can tell the difference. The seed pods are the big clue, as in A. Koa the seeds are perpendicular to the pod and in A. Koaia the are aligned. Both are very variable in morphology. I have no idea why.

Shawn said...

As I understand it, A. Koaia is also sort of a 'dwarf' koa that is shorter and bushier and prefers to grow in the more arid climates of the Kohala and Kona districts. A botanist recommended them to me as a good fast growing perimeter screen on the borders on our property, as they will grow a little bigger and faster here in the Volcano mist.

Anonymous said...

Is koa safe to plant close to your house or rock wall? I know over many years a tree can get huge but as it is growing will the roots be invasive? Just trying to figure out where to plant mine, thanks.

Ally Noel said...

I wanna be a part of the reforestation :) Where do I find the 2 varieties of seeds? Someone please help me, I Live on Big Island!

Ally Noel said...
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