Green ash

Appalachian-Blue Ridge forests

Arizona Mountains forests

Atlantic coastal pine barrens

Blue Mountains forests

Central Pacific Northwest coastal forests

Central Tallgrass prairie

Central-Southern Cascades Forests

What it needs

Conditions

Light

Full sun / Part sun

Water

Moderate water

Soil pH

Acid / Neutral / Alkaline

Acid is below pH 6.0, neutral 6.0 to 8.0, alkaline above 8.0.

Spacing

35 ft

Habit

Large deciduous tree, pyramidal when young, maturing to a more rounded but usually irregular crown

Care tips

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Do not plant a new green ash. NC State Extension and the Missouri Botanical Garden both say new planting is no longer recommended because emerald ash borer typically kills an ash within 3 to 5 years of infestation.

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If you have a healthy, valued green ash, find out whether emerald ash borer has reached your area; Wikipedia notes that insecticide injections and sprays are used to protect valued trees in parks.

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Keep an eye on an ash near a house, drive or play area: the Missouri Botanical Garden notes the branches are brittle and break in wind, snow and ice, and a borer-weakened tree only adds to that.

Lifecycle

Planting

NC State Extension and the Missouri Botanical Garden both say planting new green ash trees is no longer recommended, because of emerald ash borer. If you are caring for an existing tree, it does best in full sun in moist, well-drained loam or clay, and NC State says it tolerates occasional flooding, drought, wind, moderate salt and alkaline soil, calling it probably the most adaptable of all the ashes.

Transplanting

NC State Extension says it transplants well. Before moving or replacing an ash, check whether emerald ash borer has been found in your area; NC State and the Missouri Botanical Garden both advise against new planting.

Early growth

Young trees transplant well and grow well in a wide range of soils, per NC State Extension, and USDA PLANTS rates the growth rapid. The Missouri Botanical Garden warns that the branches are brittle and can be damaged by wind, snow and ice.

Maturity

NC State Extension and the Missouri Botanical Garden both give 50 to 70 feet tall and 35 to 50 feet wide; the Wildflower Center gives 50 to 75 feet, and Wikipedia 39 to 82 feet, rarely to 148 feet. Beyond emerald ash borer, NC State and the Missouri Botanical Garden list lilac borer, carpenterworm, oystershell scale, leaf miners, fall webworm, ash sawflies, ash leaf curl aphid and ash flower gall mite, plus leaf spots, powdery mildew, rust, anthracnose, cankers, ash yellows and a general ash decline. USDA PLANTS rates its lifespan short.

Propagation

Grown from seed, which NC State Extension recommends. The Wildflower Center gives a two-stage treatment: 60 days of warm, moist stratification followed by 120 days at 32 to 41°F. Plants For A Future suggests harvesting seed while still green and sowing it at once in a cold frame, or cold-stratifying stored seed. Most named cultivars NC State lists are seedless male selections, so they are bought as nursery trees rather than grown from seed.

Pollination

Dioecious - needs male pollinizer

Male and female flowers are on separate trees, and the flowers are wind-pollinated. Only female trees set seed: NC State Extension says male trees are usually preferred in landscapes because they produce no fruit, and the Missouri Botanical Garden says female trees produce abundant seed in some years and may self-seed freely. Most named cultivars, including Marshall's Seedless, Patmore, Summit and Cimmaron, are seedless males.

Plants don't grow alone

Larval host

Butterfly

Eastern tiger swallowtail (Papilio glaucus)

NC State Extension and the Wildflower Center both list green ash as a caterpillar host for the eastern tiger swallowtail.

Larval host

Butterfly

Mourning cloak (Nymphalis antiopa)

The Wildflower Center lists green ash among the caterpillar host plants of the mourning cloak.

Seed forage

Bird

Eastern songbirds (multi-species) (multiple species (Passeriformes))

NC State Extension says birds eat the seeds, the Wildflower Center lists its fruit as food for birds, and the Missouri Botanical Garden says it attracts birds.

Seed forage

Mammal

Eastern gray squirrel (Sciurus carolinensis)

NC State Extension says squirrels eat the seeds; it does not name the species, so the eastern gray squirrel tie is plausible rather than documented.

Foliage forage

Mammal

White-tailed deer (Odocoileus virginianus)

NC State Extension says white-tailed deer browse the foliage, though it also rates the tree deer resistant.

For people

Edible with preparation

Not a food plant. Plants For A Future rates it 1 out of 5 for edibility, for inner bark that can be cooked, and NC State Extension says the bark can be used to thicken soups or bread; USDA PLANTS gives its toxicity as none. Plants For A Future also records traditional uses of the bark as a bitter tonic and for a red dye. Its main use is the wood: NC State lists tool handles, oars, sports equipment, floors and furniture, and Plants For A Future says it is poorer than white ash wood but usually sold under that name.

Native range

Native across 42 US states + 6 CA provinces.

Worldwide native range.

Native ecoregions

Naturally belongs in 27 ecoregions - its native range crosses a state or province each one spans (not necessarily this exact habitat).

Appalachian mixed mesophytic forests

Appalachian-Blue Ridge forests

Atlantic coastal pine barrens

Canadian Aspen forests and parklands

Central Tallgrass prairie

Chihuahuan desert

Colorado Rockies forests

Cross-Timbers savanna-woodland

Eastern Canadian Forest-Boreal transition

Eastern Great Lakes lowland forests

A dense, conical-to-narrow-pyramidal evergreen tree native to eastern and central North America, prized as a screening and foundation conifer. Flat, fan-like sprays of scale-like, aromatic yellow-green foliage clothe the tree from the ground up, and red-brown bark exfoliates on mature trunks. Wild trees can reach 40 to 60 feet but cultivated plants typically stay near 20 to 30 feet; small urn-shaped cones and dense evergreen cover make it valuable food and shelter for birds.

Climate notes

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Emerald ash borer is the deciding fact for this tree. NC State Extension and the Missouri Botanical Garden both say it is a serious threat to all North American ash species, that it typically kills a tree within 3 to 5 years of infestation, and that planting new green ash trees is no longer recommended. The beetle is native to Asia and was first found in the United States in southeastern Michigan in 2002, per the Missouri Botanical Garden. Plants For A Future says the larvae can girdle trees as small as 1 inch across with virtually 100% mortality, and that because ash seed stays viable for at most 7 or 8 years, natural regeneration after an outbreak is minimal. Wikipedia reports that it kills more than 99% of green ash, that pesticide injections and sprays are used to protect valued trees in parks, and that the US Forest Service is studying rare surviving "lingering ash" trees.

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NC State Extension, the Missouri Botanical Garden and Plants For A Future all list Fraxinus pennsylvanica for USDA hardiness zones 3 to 9 (3a-9b). Plants For A Future says it tolerates about -22°F when fully dormant, and USDA PLANTS gives a minimum temperature of -47°F.

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The native range here is taken from Kew's World Checklist of Vascular Plants (WCVP), the dataset POWO publishes: most of the United States east of the Rocky Mountains, from Maine and Florida west to Montana, Wyoming, Colorado and Texas, and Utah, plus Canada from Nova Scotia, New Brunswick and Quebec west through Ontario and Manitoba to Saskatchewan. WCVP lists it as introduced in New Mexico, northeastern Argentina, much of central and eastern Europe from Spain to European Russia, the Caucasus, western Siberia, Inner Mongolia, Korea and the Russian Far East. NC State Extension, the Missouri Botanical Garden and Plants For A Future also include southeastern Alberta in the native range, which WCVP does not.

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Outside its range it has become a weed in places: Wikipedia says it is naturalized in much of the western United States, in Argentina and in Europe from Spain to Russia, and Plants For A Future records that it was grown as a timber tree in central and southeastern Europe and gives it weed potential.

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Wet-soil tolerance is its native habit. NC State Extension describes its habitat as floodplains, riverbanks and swamps, and Wikipedia says its seedlings are highly tolerant of waterlogging, which is why it grows almost entirely along streams and in bottomlands. The Wildflower Center lists it for dry, moist and wet soils. That toughness made it one of the most successful hardwoods in Great Plains shelterbelts and a tree planted on strip-mine spoil banks, per the Wildflower Center.

Similar plants

Browse lateral options with similar roles, light needs, size, or native-range overlap; these are not filtered for a better climate fit.

Thuja occidentalis

American arborvitae

A medium-to-large native shade tree of central and eastern North America, reaching 50 to 80 feet with an ovate-rounded crown and large, asymmetric heart-shaped leaves. In June it carries pale-yellow, intensely fragrant flowers on pendulous cymes - each cluster hung from a distinctive strap-like leafy bract - that ripen into pea-sized nutlets. The fragrant June bloom is a premier nectar source: Missouri Botanical Garden lists it as attracting bees and butterflies, and the Lady Bird Johnson Wildflower Center flags it as having special value to both native and honey bees.

The only native U.S. holly with both spiny green leaves and bright red berries - an upright, pyramidal, broadleaf evergreen tree that slowly matures to 15 to 30 feet in cultivation (to 50 feet in the wild). Thick, leathery, deep green leaves bear spiny marginal teeth, and pollinated female trees carry showy red-to-orange drupes that ripen in fall and persist through winter as bird food. This is the classic "Christmas holly" of wreaths and decorations.

A tough, medium-sized native tree of the eastern and midwestern United States, grown as much for its showy edible orange fruit as for its distinctive thick, dark gray bark broken into rectangular blocks. Small urn-shaped white-to-greenish-yellow flowers open in May and June, and the sweet fruit ripens after frost. Largely dioecious - a female tree needs a male pollinizer nearby to set fruit - and notably drought- and walnut-tolerant once established.

The largest native cherry of eastern North America - a medium-to-large deciduous shade tree that hangs elongated racemes of small white flowers in spring, then ripens drooping strings of pea-sized fruit from red to near-black in late summer. The fragrant white bloom feeds bees while the fruit is eaten by 33 species of birds and many mammals; it is also a workhorse larval host, supporting the Eastern Tiger Swallowtail and a string of giant silk and sphinx moths. Every part except the ripe fruit is cyanide-bearing and toxic.