Acacia kauaiensis Hillebr.
Scientific Name: Acacia kauaiensis Hillebr.
Use a soil moisture meter to monitor the soil moisture where Acacia kauaiensis Hillebr. is planted.
None A closely related species is ACKO2 - Acacia koaia: dwarf koa, koaie, koaoha, koai‘e, koaia
The primary use is for timber, though it creates wildlife habitat, and is an ornamental. Koa trees in natural ecosystems provide habitat for many plants, insects, and birds, some endangered, such as the ‘akiapōlā‘au (Hemignathus munroi), a species of honeycreeper. As a nitrogen-fixing species, koa plays an important role in forest fertility. A key traditional use of koa logs by early Hawaiians was to build canoes and make tools. Commercially, koa is the premier native timber of Hawai‘i and is one of the most expensive woods in the world. The leaves and ashes have been used medicinally by Hawaiians. Tannin from the koa bark has been used to make a red dye for traditional bark cloth. The name “koa” also means “warrior” in Hawaiian and is important culturally.
Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status (e.g. threatened or endangered species, state noxious status, and wetland indicator values).
Description and Adaptation
Koa is the largest native Hawaiian tree, It typically attains heights of 15-25 m (50-80 ft) with a canopy spread of 6-12 m (20-40 ft), Found between 100-2300 m (330-7500 ft), The form of trees ranges from an upright single trunk to low and sprawling with multiple trunks, Pale yellow flowers are borne in axillary racemes with spherical heads about 8,5 mm (0,33 in) in diameter, Flowers are produced throughout the year, peaking in mid to late winter, Seeds are contained within a pod (legume) 15-20 cm (6-8 in) long containing 6-12 seeds, There are three varieties of Acacia koa, A,koa var, koa, A,koa var, latifolia, and A, koa var, Use soil moisture sensors to measure the soil moisture of Acacia kauaiensis Hillebr.., kauaiensis, Distribution: Endemic to the Hawaiian Islands, Please consult the Plant Profile page for this species on the PLANTS Web site,
The only propagation method currently in wide use is from seed. Pods are ready to pick when their color has turned from green to brown or black. Growing koa seedlings is very similar to many other nitrogen-fixing tree species, requiring pre-germination treatment (scarification) to break through the hard, impermeable seed coat, inoculation with appropriate rhizobia bacteria, and special nutrient requirements. Trees should be inoculated in the nursery within 4 weeks of germination. Koa requires well-drained soils. Koa stands on shallow soils are not as productive as those on deep soils and may be short-lived. Koa is difficult to integrate with annual crops due to koa’s aggressive surface root system that competes with crops, while also susceptible to damage by human, animal, and machine traffic. Hawai‘i’s highly variable climate means that matching an appropriate seed source to the site conditions is important to foster a viable koa planting. Environmental tolerances of koa vary by population. Such variation is one reason that seedlings used in reforestation should come from seeds collected from sites near or similar to the planting site. Koa trees grow well only in the sun.
Overwatering and over-fertilization cause stress which often exhibits itself as yellowing of the leaves. Decreasing irrigation and eliminating nitrogen fertilizer can reverse the problem. Weed whacking the bark at the base of the tree can ruin the tree in a fraction of a second. It’s best to control weeds only by hand cutting and mulching near the tree. Leave a few inches of space against the trunk when mulching to reduce rotting. Root-bound seedlings that have become stunted in their containers will never return to being vigorous, healthy trees and should be discarded. Without adequate soil contact, newly planted seedlings can be severely set back or die within a few days of planting. When planting seedlings, especially those grown in forestry tubes, the soil should be firmed up against the seedling’s root system. Windy or shady conditions are not conducive to rapid growth. Trees should be protected from wind and given full sun most of the day. When planting dense stands of koa, failure to thin trees will cause growth to stagnate. The planting area must be fenced to exclude any grazing animals and competitive vegetation should be removed around planting holes. In urban situations, mulching with leafy materials is recommended to suppress weeds, conserve moisture, and protect koa’s surface roots. Pruning is not recommended since cuts provide easy access to fungi and borers.
|Temperature, Minimum (°F)||31|
|Adapted to Coarse Textured Soils||Yes|
|Adapted to Fine Textured Soils||Yes|
|Adapted to Medium Textured Soils||Yes|
|Cold Stratification Required||No|
|Frost Free Days, Minimum||365|
|Planting Density per Acre, Maxim||700|
|Planting Density per Acre, Minim||300|
|Root Depth, Minimum (inches)||30|
|Shape and Orientation||Erect|
|Active Growth Period||Year Round|
|Foliage Porosity Summer||Moderate|
|Foliage Porosity Winter||Moderate|
|Low Growing Grass||No|
|Height, Mature (feet)||110.0|
|Height at 20 Years, Maximum (fee||100|
|Growth Form||Single Stem|
|Vegetative Spread Rate||None|
|Fruit/Seed Period Begin||Spring|
|Seed Spread Rate||Moderate|
|Seed per Pound||4900|
|Propagated by Tubers||No|
|Propagated by Sprigs||No|
|Propagated by Sod||No|
|Propagated by Seed||Yes|
|Propagated by Corm||No|
|Propagated by Container||Yes|
|Propagated by Bulb||No|
|Propagated by Bare Root||Yes|
|Fruit/Seed Period End||Summer|
|Commercial Availability||Routinely Available|
|Propagated by Cuttings||Yes|
|Palatable Browse Animal||High|
|Nursery Stock Product||Yes|
|Naval Store Product||Yes|
|Christmas Tree Product||No|