Deciduous, Evergreen, Shrubs, Trees
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).
Grows to 20–30 ft. tall and 20–40 ft. wide. Feathery, finely cut, blue-gray leaves. Profuse, fragrant yellow flowers in early to midwinter. Most commonly planted and one of the hardiest. Wonderful on banks when grown as multitrunked shrub-tree. ‘Purpurea’, purple-leaf acacia, is as tall but not quite as wide; its new growth is lavender to purple, maturing to blue-gray. Cutting back encourages new growth and prolongs foliage color.
Grows quickly into a graceful weeping tree 15–25 ft. tall and wide, with narrow, drooping, bright green leaves up to 4 in. long. Springtime flowers are creamy yellow puffs. Damaged at 20°F (–7°C). Popular compact varieties (dense growers to just 3 ft. tall and wide) are ‘Limelight’, with lime green leaves, and ‘Mini Cog’ (‘Cousin Itt’); both are useful in containers and borders.Acacia constricta
Open, spiny, deciduous shrub 10–18 ft. tall and wide, with tiny feathery leaves. Fragrant yellow flowers in spring or summer. Valuable in desert for texture, summer flowers.
From eastern Australia. Multistemmed small tree to 10–15 ft. tall and wide, with silvery gray leaves shaped like paring knife blades. Clusters of fragrant yellow flowers in early spring. Useful as a barrier or screen, and on banks and slopes. Cut branches are attractive in arrangements.Acacia greggii
Native from California to Texas. Grows 15–25 ft. tall and 15 ft. wide, with finely divided, feathery leaves on spiny branches. Creamy yellow flowers appear in spring, then intermittently through fall. Shrubby in drought, treelike with water.Acacia iteaphylla
Beautiful, slightly weeping, spreading shrub from Australia. Grows 8–12 ft. tall and and 10–12 ft. wide. Good screen or low windbreak, especially near coast. Gray green leaves are reddish pink when new. Profuse pale yellow flowers from winter to spring.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.
Usually big, rounded, billowy shrub to 20 ft. tall and wide. Bright green leaves are 3–6 in. long. Golden yellow flowers are held on 2 1/2-in. long spikes in late winter, early spring. Very fast growing; very tolerant of adverse conditions. Used as road screening against dust and headlights. Good soil binder near the beach (winds make it prostrate). Resists oak root fungus. Often sold as Acacia latifolia.
Beautiful weeping tree from Australia, perfect for cascading from behind a wall. Makes a graceful espalier. Blue-gray leaves to 4 in. long are held on weeping branches. Yellow flowers appear erratically in spring. Slow grower to 25 ft. tall and 15 ft. wide.
Grow this Australian native as a large shrub or train it as a rounded, open-headed tree to 20 ft. tall and wide. Roundish, 1 1/2-in.-long leaves are silvery gray and satiny to the touch. Long clusters of light yellow, fluffy flowers appear in late fall or winter. Excellent for patio. Good winter color. Will not tolerate summer water. Prune heavily after flowering to keep it compact.Acacia pravissima
From eastern Australia. Grows to 12–20 ft. tall and wide, with short, triangular, gray-green leaves packed tightly along the branches. Profuse winter or spring show of cream to bright yellow, scented flowers. Endures frost, heat, wind, pollution, and marine exposure.Acacia smallii
Desert Southwest native often sold as A. farnesiana, which is cold tender. Plant A. smallii where frost occurs. Deciduous tree of variable height, reaching 10–35 ft., spreading 15–25 ft. Finely divided leaves are held on thorny branches. Puffy balls of yellow, fragrant flowers in spring.Acacia stenophylla
From Australia. Fast-growing, open, weeping tree to 30 ft. tall, 20 ft. wide. Pale green leaves long (to 16 in.), narrow, and drooping. In spring, pale yellow flowers are held on inch-long spikes. Maroon new bark. Makes nice shadows on walls. Provides lightest shade for underplantings.Acacia verticillata
Australian native to 15 ft. tall and wide, with dark green, needlelike, 3/4-in.-long leaves. Pale yellow springtime flowers in inch-long spikes. Looks like an airy, shrubby conifer. Good low hedge in wind. Unpruned, it develops an open form with many spreading, twisting trunks. Sheared, it grows dense and full. Good at beach. Resists oak root fungus.‘Desert Carpet’
Variety of a species from Australia. Tough ground cover for banks, large areas with poor soil. Endures drought and heat. Uniform growth to 1 ft. high and 12–15 ft. wide. Narrow, leathery, gray-green leaves; puffy yellow springtime flowers.
These needle grasses were once included in Stipa. All are clump formers characterized by long...
Native from British Columbia to Northern California. Grows to 5–6 ft. tall, with one to six smal...
Little-known evergreen shrubs or trees from Chile with leathery leaves, somewhat stiff growth habit, a...