The magnificent bur oak is sturdy, long-lived, and tolerant of many less-than-perfect growing conditions. Oval to wide-spreading in form, a mature bur oak has a classic, heavy-limbed oak silhouette. It has deep green foliage that may develop yellow to tan fall color. Its distinctive acorns have large, fringed caps that nearly cover the seed. Bur oak develops thick, corky bark that allows it to withstand fires in its native prairie savannas.
Common name: Bur oak
Botanical name: Quercus macrocarpa
Plant type: Large deciduous tree
Zones: 3 to 9
Height: 50 to 80 feet
Family: Fagaceae, beech family
- Sun: Full sun.
- Soil: Adaptable to almost any soil. Tolerates alkaline (high pH) soil better than other oaks.
- Moisture: Keep young trees watered during dry periods; mature trees have good drought tolerance.
- Mulch: Apply 2 to 4 inches of organic mulch in a wide circle around the base of the tree, keeping mulch several inches away from the trunk.
- Pruning: Prune young trees to maintain a single central leader and to develop a good framework of branches. On older trees, prune out dead, damaged, or crossing branches.
- Fertilizer: Apply a balanced fertilizer once per year if needed.
- Collect acorns when they drop in late summer or early fall. Sow directly outdoors; seedlings will emerge in spring.
Pests and diseases
- While bur oak can develop diseases such as anthracnose, leaf spots, and twig blight, they are rarely severe enough to affect the health of the plant.
- Gypsy moth caterpillars and other chewing insects may damage foliage.
- Bur oak is fairly slow growing, but plant it where it will have room to spread over the years.
- Another common name for bur oak is mossycup oak, referring to its fringed acorn caps.
- Bur oak is more tolerant of urban conditions (pollution, dry or compacted soil, high soil pH) than other oaks and makes a fine addition to city parks or large residential lots.
All in the family
- There are more than 600 species of oaks native to the Northern Hemisphere.
- Oak species include both deciduous and evergreen types and range in height from under 15 feet to over 100 feet.
- Oaks are some of the most valuable timber trees; their wood is used for ships, flooring, furniture, wine casks, picture frames, and many other items.
(Text by Nancy Rose, photo by Gayle Yarrington)