The silk tree (Albizia julibrissin) is a pretty looking tree with fern-like leaves and exotic-looking flowers. On each leaf there are tiny leaflets that close when touched or as the sun sets. The stunning pink flowers that initially drew attention towards the silk tree inspire the origin of its common name. Each fragrant blossom is a silky pom-pom-like flower that starts with a white base and culminates with a shockingly pink tip.
While the tree is stunningly ornamental, it is also frustratingly weedy. It was introduced to the United States in 1745 by the famous botanist André Michaux. Since that time, it has naturalized in twenty-five states. It is extraordinarily adaptable and does very well growing in disturbed soil and roadsides.
|Botanical Name||Albizia julibrissin|
|Common Name||Silk Tree, Pink Silk Tree, Persian Silk Tree|
|Plant Type||Deciduous Tree|
|Mature Size||20-40 Feet Tall 20-50 Foot Spreed|
|Sun Exposure||Full Sun to Part Shade|
|Soil Type||Average, medium moisture, well-drained|
|Bloom Time||June to July|
|Native Area||Iran to Japan|
|Toxicity||Seed pods may be toxic if ingested|
Silk Tree (Albizia Julibrissin) Care
The silk tree is certainly beautiful, but it has to be considered with some caution before planting. If in the Midwest or South, check if it is legal to plant. It is currently listed as invasive in six states. Individual localities may have it in “do not plant” ordinances in other locations.
A notorious spreader, the seeds of the Albizia Julibrissin travel and grow in disturbed areas like roadsides, woodland edges, and open fields, so it can be difficult to control without careful measures.
Other than the fact that it can get a bit untidy and needs to be planted a distance from structures due to weak wood that breaks easily under ice load and high winds, there is no simpler tree to grow once it gets going.
The silk tree is a very hardy species tolerant of a wide range of soil and moisture conditions, bolstered by its roots’ ability to fix nitrogen.
The tree tolerates partial shade but is generally considered intolerant of shade. Albizia Julibrissin will thrive in full sunlight, promoting fuller foliage and abundant flowering.
The silk tree tolerates a wide range of soil conditions and is even adapted to poor varieties. The tree’s nitrogen-fixing properties allow it to grow well in soils where other plants would suffer.
It can also handle acidic to moderately alkaline soil pH with ease and is a good choice for landscapes that need solutions for high alkaline areas.
The tree’s habit of naturalizing in wet to dry sites shows that Albizia Julibrissin is adaptable regarding moisture conditions. Giving a young tree that is freshly planted a thorough weekly soaking is essential until the roots have been established. After the first season, no supplemental watering should be needed.
Temperature and Humidity
Though it thrives in the higher temperatures of the southern USDA Zones, the silk tree is tolerant of low temperatures. Young plants, however, are frost tender and will not survive hard winters. There are cultivars available, however, like A. julibrissin’ Ernest Wilson’., that are more winter-hardy options for the northern zones. 'Ernest Wilson' also boasts pretty pink and white flowers.
The silk tree’s profuse growth shows that supplemental feeding is not needed. Compost added at the tree base should be sufficient to replenish nutrients.