Pin Oak

Size, growth and what to expect

Pin oak grows fast, about 2.75 feet a year in our growth estimator. Bottomland trees in Missouri averaged 65 feet at 30 years. Expect 50 to 70 feet with a crown 40 to 60 feet wide. It is a short-lived oak, mature at 80 to 100 years.

It flowers in April and May as the leaves unfold, and the acorns ripen in their second year and fall from September to November. Open-grown trees can bear at 15 years and stands at about 20, with a poor crop every 3 or 4 years. The acorns are about half an inch long and often striped, with a thin cap over a quarter of the nut. Mallards and wood ducks feed on them in fall, and blue jays carried off and buried 54 percent of one stand's crop in four weeks. The leaves turn deep red in fall, and young trees hold their brown leaves through winter.

It grows wild from southwestern New England west to Iowa and eastern Kansas, and south to northeastern Oklahoma, Tennessee and central North Carolina. Its home is wet bottomland that floods in winter but not in summer.

How to grow Pin Oak

Pin oak wants full sun and a moist to wet, acid soil, and it takes clay and city conditions. Plant it only where the soil is acid, since on alkaline ground its leaves yellow and the tree can die. It takes ground that floods in winter, but flooding through the growing season can kill it. Set trees 40 feet apart, and keep each one 30 feet from a wall and more than 50 feet from overhead wires.

Saplings ship bare-root or potted. Pin oak transplants easily, since a moved sapling quickly grows a wide mat of fibrous roots. Plant dormant saplings from leaf fall until bud swell, in a hole wider than the roots and no deeper. On poorly drained ground, set the tree on a low mound. Set the root flare at the soil line, put the native soil back in, and keep the mulch clear of the trunk. Red oak acorns need a winter before they sprout, and they die if they dry out. Sow them in fall an inch deep under hardware cloth. For spring, hold them damp in the refrigerator for 30 to 45 days first.

Water every week or two through the first summer, then only in a long drought. Do not let water stand around a new tree until it has rooted in, which takes a few years. Keep weeds back, and guard each sapling with a tube or mesh sleeve against deer for its first three years. Pin oak keeps its lower limbs, which droop as it grows, so remove them in the dormant season where they would be in the way.

The flowers are wind pollinated, and an acorn crop wants another oak nearby. As a red oak it can catch oak wilt, so prune only in the dormant season, to avoid the beetles that spread it. It is among the spongy moth's most favored trees, and outbreaks of the horned oak gall wasp and the forest tent caterpillar have badly damaged whole stands. Oak leaf blister, pin oak blight and twig cankers can also mark it.