Jack Pine

Size, growth and what to expect

Jack pine grows fast, about 2.75 feet a year in our growth estimator. In its first 20 years it outgrows every other conifer of its range but tamarack. It matures at 35 to 65 feet with a crown 20 to 30 feet wide. Stands break up after 60 to 80 years, though trees have reached 230, and the oldest dated by its rings reached 246.

Trees in the open begin to bear cones at 5 to 10 years. Pollen is shed in May and June, and the curved cones, 1.5 to 2 inches long, ripen in September of their second year. Over most of its range they stay sealed for years until fire or great heat opens them. The Kirtland's warbler nests only in large stands of young jack pine 5 to 20 feet tall, and red squirrels and snowshoe hares feed on it.

It grows wild across Canada from the Northwest Territories to Nova Scotia. In the United States it grows in Maine, New Hampshire, Vermont and northern New York, and from Michigan, northwestern Indiana and northeastern Illinois west through Wisconsin to Minnesota.

How to grow Jack Pine

Jack pine needs full sun and takes the poorest, driest sand or gravel. It grows best on a well-drained, acid, loamy sand and does poorly on wet ground. It takes drought and road salt but not heat, and it thrives where summers are cool. Plant it 15 feet from a wall, and set trees 20 feet apart. Keep it more than 50 feet from overhead wires.

Saplings ship bare-root or potted. Plant in early spring or fall, in a hole wider than the roots and no deeper, with the root collar at the soil line. Firm the soil around the roots and water it in. The seed needs no chilling. Sow it a quarter inch deep in spring, or outdoors in fall, and keep the bed moist. Spring-sown seedlings come up within two to eight weeks.

Water every week or two through the first summer, since drought kills many young seedlings on coarse soil. Keep grass and brush back for the first few years, because young jack pines need full sun. Deer and snowshoe hares browse young trees, and where deer are many they can kill trees up to 7 feet tall, so fence young plantings. It needs no pruning.

Each tree carries both male and female cones, and the wind carries the pollen between trees. Seedlings from a tree's own pollen seldom survive in the wild, so trees in a group bear better seed. The jack pine budworm and several sawflies strip the needles, and the sawflies can kill trees. Pine-oak gall rust can infect half of young seedlings and kills many of those with galls on the main stem. Ice storms break it badly.