Pin Oak, an Oak distributed from the middle Atlantic states westward to the edge of the Great Plains, and encompassing most of the Midwest, is often seen in the wild in wet areas (an alternative common name is Swamp Oak). In floodplains, wetlands, and low areas, Pin Oak may form nearly pure stands, and is distinctive in its dense growth habit: ascending upper branches, horizontal middle branches, and strongly downswept lower branches.
In urban areas, Pin Oak suffers from a quirk of commercial nursery production, in that most trees originate from southern sources with very acidic soils, and when transplanted to neutral or alkaline soils, suffer tremendously from leaf chlorosis with a resulting loss of vigor. The lesson still not learned is to use local seed sources for growing trees, when there will be a problem of any type.
As a general rule, Pin Oak requires moist and acidic soils to reach its full growth potential, which is a medium to rapidly growing tree (for shade, knotty timber, or quick establishment in naturalized areas). It is probably the favorite Oak to use as a shade tree, because its fibrous root system re-establishes quickly after root pruning, and because of its symmetry and the potential for quick shade with russet fall color. It thrives in full sun to partial sun (but is shade tolerant in youth), is located naturally in zones 4 to 7, but can be grown in zones 4 to 8.
Pin Oak gets its common name from the practice long ago of "pinning together" the timbers of a barn with the tough, resilient branchlets of this tree. Under optimum conditions in the Midwest, Pin Oak may reach 70 feet tall and 40 feet wide when located in the open. As a member of the Red Oak group and the Beech Family, it is related to the Beeches, Chestnuts, and other Oaks.
Planting Requirements - Pin Oak, when found as a native tree in its local ecosystem, is genetically adapted to the pH of the soil in that area. However, acorns, bare root saplings, or balled and burlapped trees often come from non-local sources, and are usually taken from areas with acidic soils. If planted in areas with neutral or alkaline soils, a chlorotic and sickly tree will result.
Potential Problems - Chlorosis is the major problem encountered, due to siting some Pin Oaks into alkaline soils (also referred to as high pH soils, low acidity soils, sweet soils, or calcareous soils). Under these conditions, Pin Oak cannot transport iron from the root zone to the above-ground structures, resulting in poor nitrogen utilization, which results in leaves that cannot synthesize enough chlorophyll (the green pigment of leaves) to conduct efficient photosynthesis, without which sugars, energy, and other biological compounds are not produced. Under these conditions, loss of vigor is a foregone conclusion.
Pin Oak may also exhibit galls due to insect feeding, and may suffer from the usual array of pests and pathogens that can affect many Oaks.