How to Grow Tree of Heaven — Ailanthus

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Ailanthus–commonly called the tree of heaven–is a spreading tree that bears small flowers in summer followed by red-brown fruits in autumn. Ailanthus is a moderately tall tree that can be grown as a specimen or as a shade tree.

Ailanthus is extremely tolerant of very poor soil and pollution. It is a good choice for planting where few other woody ornamentals would grow. Suckers and seedlings can be a problem so it is best to monitor Ailanthus

Ailanthus is native to China but it has been naturalized widely in the United States. Ailanthus is a genus of five species that occur in woodlands in China and from Southeast Asia to Australia.

Green Leaves and red flowers of Ailanthus.

Get to know Ailanthus 

  • Plant type: Deciduous trees and shrubs 
  • Growing zones and range: Zones 4 to 8
  • Hardiness: Hardy to Zone 4
  • Height and width: 40-60 feet (13-18m) tall, with an equal spread 
  • Growth rate: Fast 
  • Form and habit: Rounded, spreading
  • Foliage: Large, alternate, pinnate leaves are reddish when they unfurl in late spring, but soon turn green, are fern-shaped and from 1-3 feet (.3-1m) in length, each consists of 11 to 31 leaflets, 3-5 inches (8-13cm) long; leaves grow in bunches at the ends of heavy twigs, creating a pattern that allows sun to filter through to the ground below; although scentless on the tree, the leaves have an unpleasant odor when crushed 
  • Flowers: Either male or female flowers; both needed for fruit; male flowers are unpleasantly scented and their pollen may cause an allergic reaction; female flowers are inconspicuous clusters of tiny yellow blossoms 
  • Fruits: Handsome clusters of red-brown, winged seedpods in late summer and fall 
  • Bloom time: Late summer through late fall 
  • Uses: Specimen trees, dried arrangements, shade 
  • Common name: Tree-of-heaven 
  • Botanical name: Ailanthus 
  • Family name: Simaroubaceae 
  • Origin: China and Southeast Asia to Australia  

Where to plant Ailanthus 

  • Plant Ailanthus in sun or partial shade.  
  • Plant Ailanthus in deep, fertile, well-drained soil; extremely tolerant of very poor soil and pollution. 

When to plant Ailanthus 

  • Sow Ailanthus seed in containers in a cold frame as soon as ripe, or in spring.  
  • Remove and pot up Ailanthus suckers in winter.  

Planting and spacing Ailanthus 

  • Plant female trees only to avoid Ailanthus becoming a nuisance; female trees are also preferable because their flowers lack the odor that makes the male flowers objectionable.  
  • Plant Ailanthus 50 feet (15m) apart. 

How to water and feed Ailanthus 

  • Give Ailanthus regular water. 
  • Feed Ailanthus with an all-purpose organic fertilizer in spring. 

How to care for Ailanthus 

  • Prune Ailanthus hard annually to grow as a large-leaved shrub. 
  • Because Ailanthus are easy to grow, they can become a nuisance, sending out underground shoots to sprout into a thicket and winged seeds to take root over a wide area; the unwanted seedlings are easily avoided, however, if you plant only female trees. 
  • Prune underground shoots as soon as they appear if additional trees are not desired.  

Ailanthus pests and diseases 

  • Ailanthus resists practically all insects and diseases. 
  • Verticillium wilt, fungal stem galls, and Cristulariella rust can develop.  

Ailanthus propagation 

  • Take Ailanthus root cuttings in winter.  
  • Sow seed in containers in a cold frame as soon as ripe or in spring.

Ailanthus varieties to grow 

  • Ailanthus altissima, Tree of heaven, spreading-tree with large, oblong-elliptic, pinnate, malodorous leaves, to 24 inches (60cm) long, composed of up to 30 ovate to lance-shaped leaflets, which open reddish green and later turn mid-green. Bears terminal panicles, to 12 inches (30cm) across, of small green flowers in summer, followed by red-brown fruit, similar to those of ash (Fraxinus). To 80 feet (25m) tall and 50 feet (15m) wide. China, naturalized wide in the United States.  

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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