A native of North America, pin oak (Quercus palustris) is a deciduous tree that occurs naturally in low-elevation, swampy woodlands from southeastern Canada through Virginia and down to Arkansas. Pink oak is notable for its dark, glossy green leaves, which generally turn a rich shade of red in the fall. Dead leaves usually persist on the tree through the winter, especially on juvenile trees. This trait is called "marcescence" by botanists. Older trees are more likely to drop their leaves in the fall or early winter.
The exact reason for pin oak's leaf persistence is unknown, though Chittenden (Vermont) County Forester Michael Snyder comments on Northern Woodlands that some ecologists believe it is an adaptive response to dry, infertile locations. The theory is that dropping leaves in the spring rather than the fall would provide much needed nutrients to the soil when the tree is actively growing. Some also claim that it provides frost protection in the spring for developing buds.
Pin oak is suitable for U.S. Department of Agriculture plant hardiness zones 4 through 8, where it prefers sunny conditions. It can handle mild maritime conditions but not direct sea spray. Pin oak's species name "palustris," derived from the Latin word "palus" (marsh), references the tree's love of watery environments. The tree prefers acidic soil and is prone to a yellowing of the leaves known as chlorosis if grown in alkaline soils. Regular applications of iron foliar sprays can help retain good foliage color. Chelated iron can also be added directly to the soil in holes spread out through the tree's root zone.
Pin oak may be propagated by seed, ideally sown directly outdoors in the spring in the tree's permanent position. Though pin oak can be propagated in a pot in a cold frame, the tree generally has better vigor if started in its final location. Plants for a Future warns that pin oak transplants poorly if left in a container for more than two growing seasons. Pin oak may take up to 25 years to produce seeds.
Pin oak may develop a number of problems that affect its foliage, including leaf spots, powdery mildew, caterpillars, oak lace bugs, leaf miners and oak skeletonizers. If left unchecked, pests and diseases may cause premature leaf drop. Avoiding major cultural stressors, such as drought and nutrient deficiencies, helps protect the tree against disease and pest problems. Some people might experience allergies from the tree. Dropped acorns and leaves can create a litter problem.