Ailanthus altissima, tree of heaven
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Broadleaf Deciduous Trees

Ailanthus altissima

tree of heaven

SimaroubaceaeCentral and northern China, Taiwan

At a Glance

TypeTree
HabitSpreading
FoliageDeciduous
Height40-80 feet (12-24 m)
Width30-50 feet (9-15 m)
Maturity8 years

Growing Zones

USDA Hardiness Zones

4 - 9
Zone 4
Zone 5
Zone 6
Zone 7
Zone 8
Zone 9
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Key Features

Deer Resistant
Drought Tolerant
Maintenancehigh

Overview

Ailanthus altissima is a large deciduous tree reaching 40–80 feet (12–24 m) tall and 30–50 feet (9–15 m) wide, with an open, irregular crown. Leaves are pinnately compound, 1–3 feet (30–90 cm) long with 11–41 leaflets; each leaflet has 1–2 glandular teeth near the base and otherwise smooth margins. When crushed or cut, stems and foliage emit a strong, distinctly unpleasant odor often described as rancid peanut butter or burnt cashew. Bark is pale gray-brown with interlacing ridges; inner bark and wood are yellow. Inconspicuous yellow-green flowers appear in large clusters June through July on separate male and female trees; male flowers have an offensive smell. Female trees produce masses of single-winged samaras (keys) that turn orange-red as they ripen in late summer, persisting through winter. Seeds are extraordinarily prolific — a single large female tree can produce 300,000 or more seeds annually — and germinate prolifically on disturbed soil, pavement cracks, and building foundations. The root system is aggressive and allelopathic, releasing compounds that suppress surrounding vegetation. Cut stumps resprout vigorously. Ailanthus altissima is listed as a noxious weed in Washington, Oregon, and numerous other US states and is considered one of the most invasive tree species in North America. It is included in this collection for identification purposes only; planting is strongly discouraged.

Native Range

Native to central and northern China and Taiwan. Introduced to Europe in the 1740s and to North America in the 1780s, initially as an ornamental and silkworm host plant substitute. Now naturalized across temperate regions worldwide.

Suggested Uses

Not recommended for planting. Included in this collection for identification and recognition purposes. Horticulture students and landscape professionals should be able to identify this species in the field by its large pinnately compound leaves with basal glandular teeth, unpleasant odor, orange-red samara clusters, and vigorous stump sprouting. Early identification of seedlings in landscapes and natural areas enables timely removal before the tree becomes established.

How to Identify

Identified by very long pinnately compound leaves, 1–3 feet (30–90 cm), with 11–41 leaflets bearing distinctive glandular teeth near the leaflet base but otherwise smooth margins. Crushed stems or foliage produce a strong, unpleasant odor — diagnostic and unlike any common landscape tree. Pale gray-brown bark has interlacing ridges; inner bark and wood are distinctly yellow. Female trees produce masses of single-winged samaras that turn orange-red in late summer and persist through winter in large hanging clusters. Stumps sprout vigorously after cutting.

Appearance

Size & Dimensions

Height40' - 80'
Width/Spread30' - 50'

Reaches mature size in approximately 8 years

Colors

Flower Colors

yellow
green

Foliage Colors

green

Fall Foliage Colors

yellow

Bloom Information

Bloom Period

~4 weeks
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Summer
Blooms June through July, with large clusters of small yellow-green flowers on separate male and female trees. Male flowers have a strong, offensive odor. Female trees produce conspicuous masses of single-winged samaras that ripen orange-red August through September and persist on the tree through winter.

Detailed Descriptions

Flower Description

yellow-green

Foliage Description

medium green in summer; yellow-green in fall

Growing Conditions

Sun Requirements

Full Sun
Partial Shade
Requires 4-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range4.5 - 8.0(Neutral)
357912
Soil Types
loamclaysandsiltrocky
Drainage
well drained

Water & Climate

Water Needs

Very Low

Frost Tolerance

hardy

Time to Maturity

5-10 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Ailanthus altissima is included in this collection for identification and awareness purposes; it is not recommended for planting. It is a noxious weed in Washington and Oregon. Control of existing trees requires a combination of mechanical removal and herbicide treatment. Cut stumps resprout vigorously and must be treated immediately with a concentrated herbicide (triclopyr or glyphosate) to prevent regrowth. Foliar herbicide treatment is effective on seedlings and small stems. Repeated removal of resprouting stems over 2–3 years is typically necessary for full eradication. Seeds remain viable in the soil for 2–5 years, so the seed bank must be managed even after the parent tree is removed.

Pruning

Pruning alone does not control Ailanthus altissima — cut stumps resprout vigorously, often producing multiple stems more vigorous than the original. Cutting should be combined with immediate herbicide application to the cut stump surface. Do not allow cut material to contact soil, as stem fragments can root. Consult Washington or Oregon Department of Agriculture noxious weed guidance for current recommended control protocols.

Pruning Schedule

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summerfall

Maintenance Level

high

⚠️ Toxicity Warning

Toxic to pets and humans