Acacia
( ak - KAY - shuh )
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At-A-Glance InformationAcacia trees, commonly called Wattles, are native to the tropics and warm regions, namely Mexico and Australia. Many species are relatively short-lived (only 20-30 years) and have sometimes fragrant, clear yellow flowers in early to midwinter. They can reach about 20 feet tall and are truly in their element when grown on hillsides and banks, though some species can be grown beachside. Most species are evergreen, and can provide great shade, be used as background or screening plants, or be used as specimens. Take care when planting Acacia trees in the garden, as some species have been found to have pods, leaves, and seeds that are toxic to animals.
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Acacia Species and Varietals
The genus Acacia includes 1,084 species and varietals, and is a member of the plant family Fabaceae. The genus name is Neo-Latin, and was pulled from the Greek word 'akakia', a term used to describe a preparation extracted from the leaves and seed pods of the plant. It was first formally described by Philip Miller in his publication The Gardener's Dictionary (1754). Acacia growing zones vary by species. For more information, see the descriptions below. To find your zone, click here: Zone Map.
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Acacia aneura (Mulga) This species grows best in zones 8, 9 and 12-24. Native to Australia, it can reach 15-20 feet tall and wide, with thornless branches and gray-green to silver leaves. Yellow flowers appear in winter and spring. Great for desert landscaping. |
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Acacia baileyana (Bailey Acacia) Grown in zones 8, 9 and 13-24, and native to Australia. This is a very commonly-planted Acacia species because of its hardiness. Spreads to 20-30 feet tall and 20-40 feet wide. Leaves are fern-like and bluish grey. Bright yellow flowers bloom early to mid-winter. Variety 'Purpurea' (Purple-Leaf Acacia) is not quite as wide as the species, with purple new growth. |
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Acacia berlandieri (Guajillo) Grows in zones 10-24; heat tolerant and native to Mexico. Shrubby growth to 5-12 feet tall and 5-20 feet wide. Leaves are feathery and bright green, branches are thornless. White, fragrant flowers bloom in clusters in early spring. Useful for screening, but can be trained into a tree. |
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Acacia boormani (Snowy River Wattle) These trees grow best in zones 8, 9 and 12-24. They are native to Eastern Australia and reach 10-15 feet tall and 6-15 feet wide. Gray green leaves and fragrant, bright yellow flowers bloom in puffs at branch tips in late winter to early spring. Shrubby, and spreads by suckers so it can form a great hillside planting or wind screen. Tolerates winter wet. |
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Acacia chinchillensis (Chinchilla Wattle) This species grows best in zones 8, 9, 13-17 and 19-24. Native to eastern Australia. Shrubby growth 3-6 feet tall and wide. Feathery, gray green leaves with bright yellow ball-shaped flowers in late winter to early spring. Great for large container planting. |
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Acacia cognata (Acacia subporosa linearis) (Bower Wattle, River Wattle, Emerald Cascade Acacia) Grows in zones 16-24 quickly into a graceful tree with weeping branches 15-25 feet tall and wide. Leaves are bright green and flowers appear in puffs of creamy yellow in spring. Sensitive to temperatures under 20 degrees Fahrenheit. Compact varieties include 'Limelight' (lime green foliage) and 'Mini Cog'/'Cousin Itt'. Both of these compact varieties are good for containers and along borders. |
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Acacia constricta (Whitethorn, Mescat Acacia) Grows in zones 8-24, native to Texas, Arizona and Mexico. Open growth to 10-20 feet tall and wide. Tiny feathery leaves and fragrant yellow flowers that bloom in late spring or early summer. Red seedpods follow. Great for desert texture or as a barrier plant. |
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Acacia covenyi (Blue Bush) Native to eastern Australia, this species grows best in zones 8, 9 and 12-24. Grows quickly into either a shrub or small tree, depending on pruning. 12-20 feet tall and 10-15 feet wide, with brown branches and blue-gray leaves. Flowers are fragrant, yellow, and bloom profusely in winter and early springtime. Good windbreak or screening plant. |
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Acacia craspedocarpa (Leatherleaf Acacia) Native to Australia, this plant grows best in zones 8, 9 and 12-24. Slow-grower to 5-10 feet tall and 3-8 feet wide. Leaves are copper when young and age to gray-green. Bright yellow blooms shaped like bottlebrushes appear in spring, and seedpods follow. Very tolerant of drought, but can take regular water provided great drainage. |
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Acacia cultriformis (Knifeleaf Acacia) This species of Acacia grows best in zones 12-24. Native to Australia, it is a multi-stemmed small tree that gets 10-15 feet tall. Silver-grey leaves and clusters of fragrant yellow flowers that bloom in early spring. Great as a barrier plant or a screen. Cut branches are attractive in flower arrangements, where their leaf arrangement can be admired from a close perspective. |
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Acacia dealbata (Acacia decurrens dealbata) (Silver Wattle) Grows best in zones 8, 9 and 14-24. Native to Australia, this species gets to 40-50 feet tall and wide quickly. Feathery grey leaves and ball-shaped bright yellow flowers bloom in late winter or early spring. |
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Acacia fimbriata (Brisbane Golden Wattle) Grows best in zones 8, 9 and 12-24 and native to eastern Australia. Gets to 15-20 feet tall and 8-15 feet wide quickly. Leaves are dark green, and bright yellow flowers bloom profusely in springtime. Great screen and windbreak. Tolerates frost and wet winters well. |
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Acacia greggii (Catclaw Acacia) This species grows best in zones 10-24. This is a deciduous shrub or small tree that is native to California, Texas, and Mexico. Gets 15-25 feet tall and wide. Dark green leaves; branches have hooked thorns. Flowers are a creamy yellow and appear in spring through fall. Good barrier plants. |
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Acacia iteaphylla (Willow Wattle) Zones 8, 9 and 12-24. Native to south Australia, this is a graceful, weeping species that gets 8-12 feet tall and 10-15 feet wide. It has narrow, willow-like gray-green leaves that are reddish pink when new. Flowers are pale yellow and bloom late winter to early spring. This species is a great screen or windbreak, especially near coastlines. |
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Acacia longifolia (Sydney Golden Wattle) This billowing shrub gets 10-25 feet tall and 9-15 feet wide. Fragrant, golden-yellow flowers appear in spikes amongst leaves along branches in winter and early spring. Leaves are bright green. This species grows best in zones 8, 9 and 14-24. Resists Oak Root Fungus. |
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Acacia merinthophora (Zigzag Wattle) Grows best in zones 13-17 and 19-24; native to Western Australia. This species has an open, weeping habit and can grow to 8-12 feet tall and just as wide. Very narrow, grey-green leaves are held on zig-zag patterned branches (hence the tree's common name), and bright yellow flowers appear in winter or spring followed by slender seedpods. |
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Acacia pendula (Weeping Acacia, Weeping Myall) This species grows best in zones 13-24 and is native to Eastern Australia. Grows slowly to 25 feet tall and 15 feet wide. Blue-grey leaves with small, pale yellow flowers that bloom in clusters in late winter or early spring. Has a graceful habit that makes it great for cascading down a wall or as an espalier. |
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Acacia podalyrlifolia (Pearl Acacia) This species grows best in zones 8, 9 and 13-24. Can reach 10-20 feet tall and about as wide. Leaves are grey, round, and satin-like to the touch. Flowers are yellow and puffy, and bloom in winter or early spring. This species is great as a patio tree with great winter color. Needs to be heavily pruned after blooms expire to keep a compact shape. Doesn't tolerate summer water. |
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Acacia pravissima (Ovens Wattle) This species grows best in zones 12-24 and is native to Eastern Australia. Gets 12-20 feet tall and wide, and has profuse, triangular greyish green leaves. In winter and spring, cream to bright yellow fragrant flowers bloom. Hardy; can take frost, heat, wind, pollution and ocean exposure. |
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Acacia redolens Grows best in zones 8, 9 and 12-24. Native to Eastern Australia, this 1-6 foot tall and up to 15 foot wide plant has leathery, grey-green leaves. Flowers appear ball-shaped and fluffy in spring. It is great when used as a groundcover for banks and large areas with poor soil conditions. Can tolerate drought and heat. Varieties 'Desert Carpet' and 'Low Boy' are low-growing to 1-2 feet tall and 12-15 feet across. |
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Acacia rigens (Nealie) This species is native to most of Australia, and can reach 6-9 feet tall and wide. Thread-like leaves are silvery-grey and in winter, branches become laden with small bright yellow flowers. Not picky about soil conditions. Great when planted in front of a wall or fence, where it can show off its unique foliage and flowers. |
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Acacia schaffneri (Twisted Acacia) Native to Mexico and southern parts of Texas, this species grows best in zones 8, 9 and 12-24. It is a deciduous shrub, growing to 18 feet tall and 20 feet wide. Branches are almost black, and have a twisting, curving habit. Ferny foliage with short thorns. Ball-shaped fragrant yellow flowers appear in spring. Pruning can be done to shape branches and form a main trunk. |
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Acacia smalliii (Acacia minuta) Grows best in zones 8, 9 and 12-24. Native to Mexico and Southwestern United States. Can get 10-35 feet tall and 15-25 feet wide. This is a deciduous plant with thorns. Flowers are puffy, yellow, and fragrant and bloom in spring. |
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Acacia spectabilis (Mudgee Wattle) Native to eastern Australia, this plant grows best in zones 8, 9 and 13-24. Fast grower to 12-15 feet tall and wide. Bark is silvery-white. Leaves are fern-like, and flowers bloom in bright yellow clusters in late winter or early spring. Purple seed-pods follow. Can tolerate frost but needs well-draining soil. Great choice for smaller gardens. |
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Acacia stenophylla (Shoestring Acacia) Grows best in zones 8, 9 and 12-24. Native to Australia, this is a fast-growing tree that has an open, weeping habit. Grows to 30-40 feet tall and 20-30 feet wide. Pale green leaves droop off of branches. New bark is maroon, and cream-yellow ball-shaped flowers bloom in late winter or early spring. Great when planted in groves; provides filtered sun for under-plantings. |
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Acacia verticillata (Prickly Moses) This species grows best in zones 14-24, and is native to southeastern Australia. Gets 6-15 feet tall and wide. Dark green leaves are needle-like and short. Mimics the look of a conifer until springtime rolls around, when pale yellow flowers bloom. Great as a low hedge in windy areas and near coastlines. If left unpruned, this plant develops into a multi-trunked twisting plant. |
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Acacia vestita (Hairy Wattle) This species is native to southeastern Australia, and grows 12-20 feet tall and wide. Branches have a weeping habit and carry soft gray-green leaves. This is a beautiful plant in springtime, when it is covered with profuse yellow blooms. Can be used as a focal point in landscapes or as a low screen or windbreak. Tolerates extremes of both drought and flooding. Grows best in zones 13, 15-17 and 19-24. |
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Acacia willardiana (Palo Blanco) Grows best in zones 12-24; deciduous and native to Mexico. Airy, graceful habit that gets to 20 feet tall and 10 feet wide. Fernlike leaves drop early, and pale yellow flowers appear in early spring. Bark is papery, and cream-colored. |
Caring for and pruning Acacia Trees
Acacias can be planted either in the ground or in large containers. Plant your Acacia in full sun exposure; some species will have different light requirements, so be sure to check before planting. As a general rule of thumb, these trees should be receiving between 6 and 8 hours of sun each day. Ensure that soil is well-draining; these plants do not like to have wet feet and have issues with fungal diseases. Mulch around the base of the tree after planting to increase soil moisture retention and suppress weed growth. Allow the top inch of soil to dry out between waterings, and be very careful not to overwater. The natural habitat of these trees is warm, so they can take a lot of heat, but will struggle in cooler winter temperatures. Most species are not frost tolerant and will need some protection.
Prune to maintain shape and size. Remove dead, dying, or diseased branches as needed. Pruning is best done in the early springtime, before new growth pushes out for the year. If a more intense rejuvenation pruning is needed, some species will bounce back from being cut back to about three feet from the ground. This will encourage shoots to form from the base and will create a bushier plant. These trees are not heavy feeders, but can benefit from the addition of a balanced, all-purpose fertilizer in spring and summertime to support new growth. Some Acacia species will need to be staked or supported when they are young in order to help them establish a strong main trunk. If growing an Acacia tree in a container, make sure to repot every two years to allow room for the root ball to grow, and provide them with more water and fertilizer than you would an in-ground tree.
Prune to maintain shape and size. Remove dead, dying, or diseased branches as needed. Pruning is best done in the early springtime, before new growth pushes out for the year. If a more intense rejuvenation pruning is needed, some species will bounce back from being cut back to about three feet from the ground. This will encourage shoots to form from the base and will create a bushier plant. These trees are not heavy feeders, but can benefit from the addition of a balanced, all-purpose fertilizer in spring and summertime to support new growth. Some Acacia species will need to be staked or supported when they are young in order to help them establish a strong main trunk. If growing an Acacia tree in a container, make sure to repot every two years to allow room for the root ball to grow, and provide them with more water and fertilizer than you would an in-ground tree.
Propagation
Acacia can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your tree, follow the instructions below:
Propagating Acacia by Cutting
Propagating Acacia by Seed
Propagating Acacia by Cutting
- Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
- In late summer or early fall, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more semi-hardwood 2-6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
- Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth on your propagation, you'll know you have roots.
- Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub. Do not allow the Acacia to stay in a small pot for too long, as their root systems need space and depth to grow correctly.
Propagating Acacia by Seed
- Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
- Harvest your seeds. The seed pods on Acacia trees are pretty easy to spot, they're large and dangle from the branches, left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
- Place your seeds in a bowl and pour boiling water over them. This will get rid of the hard coating on the seeds, allowing them to germinate and grow. Leave the seeds in the water for 24 hours, and then lay them out to dry. Your seeds are now ready to be planted.
- Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 10-20 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
- Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home
Acacia seeds are held in pods that dangle from the branches of the tree once flowers have faded.
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Acacia seeds vary a bit in color, depending on the species, but will generally look like these.
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Problems and Pests
Acacia trees and shrubs are known for having issues with the following pests and diseases:
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For information on how to treat these issues in Acacia trees, see the following links:
Gallery
Acacia baileyana 'Purpurea' has purple new growth.
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Acacia cognata 'Cousin Itt', a popular dwarf varietal.
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Acacia cognata 'Limelight' compact varietal.
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The striking, creamy-white papery bark of Acacia willardiana.
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Acacia podalyrlifolia, or Pearl Acacia, is great for patios or along walkways and sidewalks, where its gorgeous foliage can be admired close-up.
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Videos
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Learn about some species of Acacia.
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How to prune a Mimosa tree.
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Resources
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 125 - 127, Acacia
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