John Rickard
Family
Fabaceae
Botanical Name
Acacia cultriformis
Plant Common Name
Knife Acacia
General Description
This tough medium-sized tree is native to eastern Australia where it thrives on arid rocky ridges along the coasts and inland. It has a high degree of drought, salt and wind resistance.
Knife acacia has a large twiggy canopy that becomes cloaked in blue-green leaf-like structures called phyllodes, which are triangular and held very close on the stem. This acacia blooms in spring with large clusters of fragrant bright yellow flowers that are pea-sized and round. They are highly attractive to bees and other pollinators and are followed by moderately attractive drooping pods.
Sun and perfectly drained soil are a must for this tree. It is important to water it deeply while young to encourage deep rooting. It can be gently pruned or clipped into more formal and neat shapes, though pruning should only be done directly after flowering. Knife acacia is an ideal tree for highway screening and wind barriers as well as residential gardens.
Characteristics
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AHS Heat Zone
12 - 10
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USDA Hardiness Zone
10 - 12
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Sunset Zone
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
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Plant Type
Tree
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Sun Exposure
Full Sun
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Height
10'-15' / 3.0m - 4.6m
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Width
10'-15' / 3.0m - 4.6m
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Bloom Time
Spring, Late Spring
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Native To
Australia
Growing Conditions
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Soil pH
Acidic, Neutral, Alkaline
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Soil Drainage
Well Drained
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Soil type
Clay, Loam, Sand
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Tolerances
Drought, Salt
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Growth Rate
Fast
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Water Requirements
Xeric/Desert, Drought Tolerant
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Habit
Upright/Erect
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Seasonal Interest
Spring
Ornamental Features
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Flower Interest
Showy
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Flower Color
Yellow
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Foliage Color (Spring)
Blue Green
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Foliage Color (Summer)
Blue Green
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Foliage Color (Fall)
Blue Green
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Foliage Color (Winter)
Blue Green
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Bark Color
Brown
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Fragrant Flowers
Yes
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Fragrant Fruit
No
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Fragrant Foliage
No
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Bark or Stem Fragrant
No
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Flower Petal Number
Single
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Repeat Bloomer
No
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Showy Fruit
No
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Edible Fruit
No
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Showy Foliage
No
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Foliage Texture
Medium
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Foliage Sheen
Matte
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Evergreen
Yes
