# Bur Oak (Quercus macrocarpa)

> A massive, drought-hardy oak of the prairie edge, with corky bark, a broad crown and the biggest acorns of any native oak in fringed, mossy cups.

Also called mossycup oak, burr oak, prairie oak. Category: Classic Oaks. Grown from seed by Blue Whale Trees. Web version: https://bluewhaletrees.com/plants/bur-oak/

![Bur oak (Quercus macrocarpa), a large open-grown tree in full leaf with a broad crown in a park](https://bluewhaletrees.com/img/plants/bur-oak-h1610-800.jpg)
*Photo: Larry D. Moore, CC BY 4.0 · [Wikimedia Commons](https://commons.wikimedia.org/wiki/File%3AOak_Tree_Lake_Tawakoni_State_Park_Texas_2023.jpg)*

## Facts

- Type: Large tree
- Mature height: 60 to 80 ft
- USDA hardiness zones: 3 to 8
- Grows wild in: Dry uplands, floodplain forests, old fields and edges
- Native range: 34 states and the District of Columbia, north to North Dakota, south to Louisiana and west to Montana (Alabama, Arkansas, Connecticut, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New York, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, Wisconsin, Wyoming and the District of Columbia). Also recorded in 2 other states, outside its native range
- Sun: Full, Part
- Soil moisture: Average, Dry
- Growth rate: Slow
- Traits: Drought tolerant, Wildlife value, Street tree, Edible
- Sold as: Saplings, Acorns

Heights and zones are typical ranges for the species in cultivation; local conditions and seed source shift them.

## Availability

Not yet priced online. Ask at captain@bluewhaletrees.com or leave an email on the web page to be told when it is listed.

## Notes

Bur oak is the great oak of the prairie edge, reaching farther north than any other American oak and spreading west into the Great Plains. It grows on limestone bluffs, sandy plains, savannas and river bottoms, often standing alone in grassland. Its acorns are the largest of any native oak, set in deep cups with a mossy fringe that gives the names bur oak and mossycup oak. Thick, corky bark lets old trees live through prairie fires. It also makes a fine street tree. Give it a large lawn, a park or a pasture, where its broad crown of heavy limbs has room to spread.

## Size, growth and what to expect

Bur oak grows slowly, about a foot a year in our growth estimator. Shelterbelt trees in the northern Great Plains grew about as much. Expect 60 to 80 feet with an equal spread. On the best bottomland soils it grows 80 to 100 feet tall, while on dry western bluffs it may stay a shrub. Many trees live 300 to 400 years.

It flowers from April in the South to mid-June in the North as the leaves open, and the acorns ripen the same year, dropping from August to November. Trees seldom bear before about 35 years, then give good crops every 2 to 3 years and go on bearing as late as 400. Each acorn is 1 to 2 inches long, biggest in the South, with the cup covering half or more of it. Red squirrels, deer, black bears, wood ducks, cottontails and mice eat them. The Cheyenne ate them too, in a mush with buffalo fat.

It grows wild from New Brunswick and Maine west to southern Manitoba and eastern Montana, south through the Great Plains to Texas, and east to Alabama, Tennessee and Maryland.

## How to grow Bur Oak

Bur oak wants full sun or light shade and grows in almost any soil, from sand and gravel to heavy clay. It takes lime, drought and city air better than most oaks. Bottomland trees take a brief spring flood, but standing water kills it. Set trees 60 feet apart, and keep each one 40 feet from a wall and more than 50 feet from overhead wires.

Saplings ship bare-root or potted. Its taproot runs deep from the first summer, so plant it young. Plant from leaf fall until bud swell, in a hole wider than the roots and no deeper. Set the root flare at the soil line, put the native soil back in, and keep the mulch clear of the trunk. Bur oak acorns die if they dry out, and those from northern trees wait for a winter's cold before they sprout. Sow them on arrival in fall, 1 to 2 inches deep, under hardware cloth. For spring, hold them damp in the refrigerator for 30 to 60 days first.

Water every week or two through the first summer, then only in a long drought. Deer, rabbits and livestock browse young bur oaks, so guard each sapling with a tube or cage for its first three years. Keep one leader while the tree is young, and prune only in the dormant season.

The flowers are wind pollinated, and an acorn crop wants another oak nearby. A tree sheds its pollen before its own female flowers are ready, so it seldom if ever pollinates itself. As a white oak, it ripens its acorns in one season. Oak wilt troubles it less than the red oaks, though the disease can pass through joined roots and has killed whole groves, so prune in the dormant season. In one Illinois study, insects had infested 43 to 100 percent of the acorns gathered from bur oaks. The oak lace bug can strip shelterbelt trees in dry weather, and bur oak blight has been found in a few places in Illinois.

## Sources

- [USDA Forest Service, Silvics of North America: Bur Oak, Johnson 1990](https://research.fs.usda.gov/silvics/bur-oak)
- [USDA Forest Service, Fire Effects Information System: Quercus macrocarpa, Gucker 2011](https://www.fs.usda.gov/database/feis/plants/tree/quemac/all.html)
- [Flora of North America, vol. 3: Quercus macrocarpa](http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233501058)
- [USDA Forest Service, Field Guide to Native Oak Species of Eastern North America, FHTET-03-01, Stein, Binion and Acciavatti 2003](https://rngr.net/publications/field-guide-to-native-oak-species-of-eastern-north-america)
- [NC State Extension Gardener Plant Toolbox: Quercus macrocarpa](https://plants.ces.ncsu.edu/plants/quercus-macrocarpa/)
- [Missouri Botanical Garden Plant Finder: Quercus macrocarpa](https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=280704)
- [The Morton Arboretum: Bur oak](https://mortonarb.org/plant-and-protect/trees-and-plants/bur-oak/)
- [Lady Bird Johnson Wildflower Center: Quercus macrocarpa](https://www.wildflower.org/plants/result.php?id_plant=QUMA2)
- [Missouri Department of Conservation Field Guide: Bur Oak](https://mdc.mo.gov/discover-nature/field-guide/bur-oak-burr-oak)
- [Virginia Tech Dendrology: bur oak](https://dendro.cnre.vt.edu/dendrology/syllabus/factsheet.cfm?ID=72)
- [Trees and Shrubs Online, International Dendrology Society: Quercus macrocarpa](https://www.treesandshrubsonline.org/articles/quercus/quercus-macrocarpa/)
- [USDA Forest Service, Woody Plant Seed Manual (2008), Quercus chapter, Bonner](https://www.fs.usda.gov/nsl/Wpsm/Quercus.pdf)
- [NatureServe Explorer: Quercus macrocarpa](https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.158441/Quercus_macrocarpa)

## Read before planting

- [Ten planting mistakes that quietly kill trees](https://bluewhaletrees.com/articles/ten-planting-mistakes/index.html.md)
- [Transplanting young trees: timing, water and protection](https://bluewhaletrees.com/articles/transplanting-young-trees/index.html.md)
- [Protecting young trees from voles, rabbits, deer and squirrels](https://bluewhaletrees.com/articles/protecting-trees-from-animals/index.html.md)
- [Tree roots run shallow and wide, not deep: what that means for watering, mulch and the house](https://bluewhaletrees.com/articles/tree-roots-run-shallow-and-wide/index.html.md)
- [Native trees for the Great Lakes and Midwest: Michigan, Ohio, Indiana, Illinois and Wisconsin](https://bluewhaletrees.com/articles/native-trees-for-the-great-lakes-and-midwest/index.html.md)
- [Red oaks and white oaks, and where each belongs](https://bluewhaletrees.com/articles/red-oaks-and-white-oaks/index.html.md)

## Related

- [Planting-site check](https://bluewhaletrees.com/tools/site-check/index.html.md): for a thrive, struggle or fail verdict on Bur Oak, add ?species=bur-oak with zone (2 to 10), sun (full, part, shade) and moisture (dry, average, wet) to that address, for example ?species=bur-oak&zone=3&sun=part&moisture=average.
- [Companion species for Bur Oak](https://bluewhaletrees.com/tools/companions/index.html.md?species=bur-oak): the natives that share its ground and the plants that pair with it in a yard.
- [Growth estimator](https://bluewhaletrees.com/tools/growth/index.html.md): how the height and trunk projections are made; the estimate itself runs in the browser at https://bluewhaletrees.com/tools/growth/#species=bur-oak
- [Seed sowing planner](https://bluewhaletrees.com/tools/sowing/index.html.md): how Bur Oak is sown, in the chart for every species (treatment, cold days, depth, timing); the dated plan runs in the browser at https://bluewhaletrees.com/tools/sowing/#species=bur-oak
- [Pollination planner](https://bluewhaletrees.com/tools/pollination/index.html.md): what Bur Oak needs for a crop and how many to plant, in the table for every species; the planner runs in the browser at https://bluewhaletrees.com/tools/pollination/#plants=bur-oak:2
- [Bloom and fruit calendar](https://bluewhaletrees.com/tools/calendar/index.html.md): the months Bur Oak flowers and fruits, in the grid for every species.