Tree of heaven

Botanical name

Ailanthus altissima

Type

Fast-growing deciduous tree from China, short-lived

Size

Can reach 60 to 70 feet (USDA Forest Service)

Hardiness

Zones 4 to 8 (Utah State University); zones 6b to 7b here

Where it is found

Alleys, fence lines, vacant lots and older yards on the valley floors, about 4,000 to 5,200 feet

Known weak points

Brittle wood, root suckers, strong odor, vigorous regrowth after cutting

Tree of heaven shows up in alleys, along fences and in neglected corners of older lots, usually first noticed as a thicket of tall shoots. The USDA Forest Service lists it as invasive or noxious on many lands. This page covers how to identify it, where it grows in our elevation bands and when pruning or removal is the right call.

How do you identify tree of heaven?

The leaves are the clue. Each is one to two and a half feet long, pinnate, with 11 to 41 leaflets, according to Utah State University. The Forest Service describes glands on the underside of the leaflets and a strong, unpleasant odor when the leaves are crushed. Twigs are coarse and velvety with a brown pith and no terminal bud.

Bark on young trees is smooth and thin. In summer the female trees carry big clusters of winged seeds, yellow-green turning orange-red and then brown, that look like maple keys with a twist.

• Very long compound leaves with 11 to 41 leaflets
• Unpleasant smell when crushed
• Clusters of twisted, winged seeds
• Thickets of shoots from roots and stumps

Where does it grow in Reno, Carson City and the Carson Valley?

It is a tree of disturbed ground on the valley floors. The Forest Service reports it up to about 6,600 feet in California, and Utah State rates it hardy to zone 4, with high drought, salt and alkalinity tolerance. In practice that covers Reno (4,505 feet), Sparks (4,413 feet), Carson City (4,680 feet) and Minden (4,725 feet); the sources we read describe it as a tree of disturbed, harsh urban sites.

At the Tahoe basin, Incline Village is 6,437 feet and Kingsbury is 7,126 feet, and cold, snow and thin soil are the limits. We do not claim a range for the basin because none of the sources we read give one.

What goes wrong with it here?

The wood is brittle. Utah State calls the tree weak-wooded and fairly short-lived, with weak branch structure, so limbs and whole stems break in wind and snow. A tree of heaven over a fence, car or roof is a failure waiting for a storm. See storm and snow-load breakage.

The second problem is regrowth. Forest Service sources say it sprouts vigorously from roots, the root crown and the trunk after top-kill, and that fire can increase its abundance. A clump that shows up along a foundation or sewer line may be root suckers from a tree on the next lot. Roots and sprouts near paving are covered in tree roots, sidewalks and sewer lines.

Pruning, cabling or removal: which is the right call?

Pruning a tree of heaven rarely solves anything. The tree answers cuts with new, vigorous shoots, and the structure is brittle to begin with. Dead and hanging limbs can come out any time, but if the tree is large and next to a structure, the sound choice is removal.

A removal crew cuts the tree down in sections and hauls the brush. The stump and roots then keep sending up shoots, so stump grinding is part of the job and the arborist explains at the estimate that sprouts may return. We do not apply herbicides. Large old trees over buildings are large tree removal jobs, and clumps along a back lot line may be a lot clearing job.

What does Battle Born Tree Service do about a tree of heaven?

The free estimate is where this gets decided. We assess the tree in person, and the arborist's call is one of removal with the stump ground. We hold a Nevada Business License (#20131580674) and are fully insured, and two of the eight crew members are ISA Certified Arborists (WE-11728A is one person's credential). If you are wondering about the wood, call the office; we publish no wood types or terms.