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Zones H1, H2
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Full
Minimal Water
Minimal

Acacia koa

Koa
Fabaceae (Leguminosae)
Evergreen, Trees

ACACIA

Native to tropics or warm regions, notably Australia, Mexico, and the southwestern U.S. Of the many species tested over the past 150 years, more than two dozen serve beautifully and functionally in Western landscapes, and new species are continually being tested.

Of species in use today, several offer fountains of clear yellow flowers in early or midwinter. Some are quite fragrant when in bloom. Many decorate and protect hillsides, banks, freeway landscapes. Some serve well in beach plantings. All are attractive to birds.

Most nurseries sell only a few of the many acacia species, but you can easily grow acacias from seed you collect yourself or order from a specialist.

Acacias differ widely in foliage and growth habit. Some have feathery, much-divided leaves; others have flattened leafstalks that fulfill the function of leaves. Many start life with feathery leaves and later develop leathery ones.

You can prune acacias or leave them to their own devices. Larger-growing species may end up as shrubs or trees depending on how they are treated in youth. Removing the lead shoot makes the plant grow as a shrub; removing the lower branches makes it treelike. It’s best to prune trees to open up their interiors; this will reduce dieback of shaded branches and prevent wind damage. Thin by removing branches all the way to the trunk.

Many acacias are relatively short lived—20 to 30 years. But if a plant reaches 20 ft. high in 3 years, the short life can be accepted.

Acacias seldom suffer pest damage. Where water is bad and salts accumulate, many become chlorotic (as do numerous other plants in such soil).

Acacia koa

Native Hawaiian tree grows 60 ft. tall and wide and produces a beautiful hardwood. Leaves are feathery in young trees, turning leathery as tree ages, curved, 6 in. long, up to 1/2 in. wide. Clusters of yellow flowers appear in spring.

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