Willow oak

Appalachian-Blue Ridge forests

Arizona Mountains forests

Atlantic coastal pine barrens

Blue Mountains forests

Central Pacific Northwest coastal forests

Central-Southern Cascades Forests

Chilean Matorral

Colorado Rockies forests

Cross-Timbers savanna-woodland

Appalachian mixed mesophytic forests

What it needs

Conditions

Light

Full sun / Part shade

Water

Consistent moisture

Spacing

25 ft

Habit

Large deciduous oak, 40 to 75 feet tall and 25 to 50 feet wide, narrowly pyramidal when young and opening with age into a dense, broad oval-to-rounded crown on a straight central trunk. The branching is fine and twiggy rather than heavy, which is what gives the tree its unusually light texture for an oak.

Care tips

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Test your soil pH before planting. Willow oak needs acidic ground; on alkaline or limestone soil it develops chlorosis that no amount of feeding permanently fixes.

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Do not judge the shape for twenty years. A young willow oak is narrow and pyramidal and looks nothing like the broad-crowned street tree you are expecting - the transformation is real but slow.

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Use it where oaks usually fail: heavy clay, low ground that stays wet, or a street strip. This is one of the few large oaks genuinely comfortable in all three.

Lifecycle

Planting

Plant in spring in full sun to part shade, in moist, slightly acidic clay or loam. It adapts to a wide range of soils including heavy clay with poor drainage, and it tolerates periodic flooding - this is a bottomland tree by origin. Avoid alkaline soil, where it becomes chlorotic. Give it 30 to 50 feet of room.

Transplanting

Transplants far more easily than most oaks, which is a real part of its popularity in the nursery trade - unlike its tap-rooted relatives it moves readily as balled-and-burlapped stock. Move it in spring rather than autumn.

Early growth

Fast for an oak, often 24 inches a year on a good site. Prune for a single central leader in the first decade while the tree is still narrow and pyramidal; the fine, twiggy branching makes structural pruning easy and rarely urgent.

Maturity

Long-lived, structurally sound and notably low-maintenance. Willow oak has good general resistance to the pests and diseases that trouble other oaks, though oak wilt and anthracnose can occur. Prune in late winter, and avoid pruning in spring in oak-wilt regions.

Propagation

From acorns, which ripen in the second autumn after flowering as members of the red oak group do. Sow fresh with a period of cold stratification; the small acorns are produced abundantly on mature trees and germinate readily.

Pollination

Wind-pollinated

Monoecious and wind-pollinated - drooping male catkins and inconspicuous female flowers appear on the same tree in April as the leaves emerge. A single tree sets acorns on its own, though oaks cross-pollinate freely and a group produces heavier crops.

Plants don't grow alone

Larval host

Moth

Polyphemus moth (Antheraea polyphemus)

Polyphemus moth is a well-documented oak feeder. Oaks are the single most important native larval host genus for Lepidoptera in North America, so a willow oak of any size feeds a substantial share of the local caterpillar community - which in turn is what feeds nesting songbirds.

Larval host

Moth

Imperial moth (Eacles imperialis)

Imperial moth larvae feed on oak foliage alongside the hairstreaks and duskywings that also use Quercus. The Lady Bird Johnson Wildflower Center specifically lists white M hairstreak and Horace's duskywing as willow oak larval users.

Seed forage

Mammal

Eastern gray squirrel (Sciurus carolinensis)

Squirrels eat and cache the small half-inch acorns heavily. Willow oak is a notably reliable and abundant acorn producer, and the caching behaviour disperses it well beyond the parent tree.

Seed forage

Mammal

White-tailed deer (Odocoileus virginianus)

Deer feed on fallen acorns through autumn and winter; willow oak contributes to the bottomland mast crop that drives deer foraging across the Southeast.

Seed forage

Bird

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

The small acorn size makes willow oak unusually accessible to birds - jays, woodpeckers, wild turkey and waterfowl all take them, where the larger acorns of white oaks are beyond many species. The Wildflower Center also records the tree as a nesting site, cover, and foraging substrate for insectivorous birds.

For people

Edible with preparation

The acorns are edible only after leaching. As a red-group oak its acorns are high in tannin and bitter raw, and they need repeated soaking or boiling in changed water before use as flour - the traditional preparation across acorn-eating cultures. Not a practical garden food source, and the tannins that make them bitter also make quantities of acorns and foliage a real risk to horses and livestock.

Native range

Native

Naturalized

Native across 21 US states; naturalized in 1 US state.

Worldwide native range.

AHS heat range

4-11

Native ecoregions

Naturally belongs in 16 ecoregions - its native range crosses a state or province each one spans (not necessarily this exact habitat).

Appalachian-Blue Ridge forests

Atlantic coastal pine barrens

Central Tallgrass prairie

Chihuahuan desert

Cross-Timbers savanna-woodland

Eastern Great Lakes lowland forests

Edwards Plateau savanna

Flint Hills tallgrass prairie

Mississippi 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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Native to the southeastern and south-central United States - the Lady Bird Johnson Wildflower Center gives the range as eastern Texas to northern Florida, north to southern Illinois and New Jersey, on alluvial soils, moist forests, stream banks and bottomlands. POWO returned HTTP 403 throughout this batch, so the WGSRPD range was joined through the committed gazetteer from that per-state native distribution.

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The northern edge of the range is genuinely fuzzy. Long Island is within it, so New York is mapped native; Connecticut is the marginal case, present in occurrence records but with the few known trees more plausibly planted than wild, so it is carried as ESTABLISHED rather than native and the map shows it in the naturalized layer. Treat the northernmost states as the limit of the species rather than as reliable garden range.

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Missouri Botanical Garden rates it USDA zones 5 to 9, which extends it well north of its native range as a planted tree - willow oak is widely and successfully used as a street tree in the lower Midwest and mid-Atlantic.

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Its defining tolerances are wet ground and cities. It takes clay, poor drainage, periodic flooding and urban pollution, which is why it is specified for rain gardens and street plantings as often as for lawns. The real limit is soil pH: it needs acidic ground and will yellow with chlorosis on alkaline soil, so a limestone site is the wrong site.

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Plotwright assigns an editorial AHS heat range of 4-11, reasoned from the cited Lady Bird Johnson range and Missouri Botanical Garden cultivation notes rather than from the USDA zones above. Its native span from eastern Texas and northern Florida to southern Illinois, New Jersey and Long Island covers a long hot southern season but not the coolest continental tier. The broader planted street-tree envelope is corroborating context, not a reason to claim coldest-summer adaptation; wet-ground tolerance also does not change that heat floor. This is a conservative Plotwright interpretation, not a copied AHS rating.

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

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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.

Full sun / Part shade

A small native deciduous tree (or thicket-forming, suckering shrub) of eastern and central North America, grown for clouds of fragrant white 5-petaled flowers that open in March before the leaves and for the edible red plums that follow in early summer. It forms a broad, spreading crown with attractive dark reddish-brown twigs that sometimes carry thorny lateral branchlets. A documented larval host for swallowtails and other butterflies, with flowers of special value to native, bumble, and honey bees.