Pin Oak

Pin oak is a medium-sized deciduous tree that grows 60 to 75 feet tall with a pyramidal form when young, broadening with age into a distinctive branching pattern; lower limbs descend sharply, middle branches extend horizontally, and upper branches ascend steeply, creating a sculptural silhouette. You recognize it by its glossy dark green leaves with 5 to 7 lobes separated by deep, U-shaped sinuses, each lobe bristle-tipped; in fall the foliage ranges from bronze and russet to brilliant red. Acorns are small at about 1.5 centimeters, enclosed only at the base by a thin, saucer-like cup. Named for the persistent pin-like stub branches that remain after lower limbs die and break off, this fast-growing oak reaches 40 feet within 20 years.

Site pin oak in full sun on moist, acidic, well-drained soils with pH between 4.5 and 6.5; it tolerates poorly drained and seasonally wet soils, even short-term flooding, reflecting its native habitat in lowland swamps and bottomlands. The shallow root system makes it easier to transplant than many oaks. In alkaline or neutral soils, iron chlorosis may develop, turning foliage yellow and causing premature leaf drop; restrict planting to acid soils. Water needs remain high, especially during establishment and hot, dry summers. PNW records document 14 diseases and 14 pests, including sudden oak death, anthracnose, and various gall-forming insects; monitor foliage and branches for these common oak problems. Many leaves persist through winter, extending visual interest into dormancy.