Jack pine (Pinus banksiana) is a tree that cannot be tamed—this small to medium-sized evergreen grows its own way and takes over with large stands of growth even where wildfires have left the land barren. At the same time, these conifer trees are practically maintenance-free and make a hardy addition to any landscape that is characterized by poor, rocky soil.
I. Appearance and Characteristics
Jack pine (Pinus banksiana), also known as grey pine or scrub pine, is a North American pine.
Its native range in Canada is east of the Rocky Mountains from the Mackenzie River in the Northwest Territories to Cape Breton Island in Nova Scotia, and the north-central and northeast of the United States from Minnesota to Maine, with the southernmost part of the range just into northwest Indiana and northwest Pennsylvania.
Pinus banksiana ranges from 9–22 m (30–72 ft) in height. Some jack pines are shrub-sized, due to poor growing conditions. They do not usually grow perfectly straight, resulting in an irregular shape similar to pitch pine (Pinus rigida). This pine often forms pure stands on sandy or rocky soil. Many populations are adapted to stand-replacing fires, with the cones remaining closed for many years, until a forest fire kills the mature trees and opens the cones, reseeding the burnt ground. Other populations have not been shaped by regular stand-replacing fires and have reduced serotiny. A population on the Maine coast is apparently not reliant on fire for reproduction, and some stands have developed several age classes. Populations with lower serotiny are often found on soils that are in some way limiting to faster-growing competition, such as soils shallow to bedrock, shallow to water table, or very young soils.
Its leaves are needle-shaped, evergreen, in fascicles of two, needle-like, straight or slightly twisted, stiff, sharp-pointed, light yellowish-green, spread apart; edges toothed and 2–4 cm (3⁄4–1+1⁄2 in) long. The bundle-sheath is persistent. The buds are blunt pointed, up to 15 mm long, reddish-brown, and resinous. On vigorous shoots, there is more than one cyclic component. The bark is thin, reddish-brown to gray in color in juvenile stages. As the tree matures it becomes dark brown and flaky. The wood is moderately hard and heavy, weak, light brown. The seed cones vary in shape, being rectangular to oval, cone shaped, straight or curved inward. The cones are 3–5 cm (1+1⁄4–2 in) long, the scales with a small, fragile prickle that usually wears off before maturity, leaving the cones smooth.
Unusually for a pine, the cones normally point forward along the branch, sometimes curling around it. That is an easy way to tell it apart from the similar lodgepole pine in more western areas of North America. The cones on many mature trees are serotinous. They open when exposed to intense heat, greater than or equal to 50 °C (122 °F). The typical case is in a fire, however cones on the lower branches can open when temperatures reach 27 °C (81 °F) due to the heat being reflected off the ground.
II. Types of Jack Pine Tree
- ‘Uncle Fogy’ has branches that twist and turn in all directions, forming a weeping mound about 4 feet tall and wide.
- ‘Schoodic’ has a dense, spreading growth habit and emerald-green needles. It only grows 1 foot tall. Unlike the species, this variety is very slow growing, spreading about 4 feet in 10 years.
- ‘Jack’s Beanstalk’ is a very narrow, columnar dwarf variety. It reaches 4 to 10 feet in height and 2 to 3 feet in width.
- ‘Harlow Lake’ is a dwarf variety with a pyramidal shape and dark green foliage.
III. How to Grow and Care
Sunlight
Jack pine seedlings are dependent on full sun at the start of their growth cycle, and these trees do best with at least 6 hours or more of direct sun throughout their life cycle. In fact, lower branches of the tree sometimes die because of being shaded from the sun’s rays by the tree’s canopy.
Temperature and Humidity
The jack pine exhibits tremendous hardiness in the cold, and can survive even the frigid winter temperatures of USDA hardiness zone 2. However, they don’t fare so well in hot, humid summer conditions and prefer climates with short, warm to cool summers. It’s no surprise, then, that these trees are often found in the greatest numbers in the United States in the northern states of Michigan, Minnesota, and Wisconsin
Watering
Jack pine is not dependent on an abundance of water. This drought-tolerant tree species would much prefer dry conditions to being swamped in wet soil. As a hardy conifer, it’s unlikely that you’ll have to supplement this tree with a regular watering schedule. Unless extreme conditions prevail, the jack pine is generally satisfied with the annual rainfall it receives.
Soil
The jack pine is able to adapt to very dry soil conditions and is often found in sandy soil. However, it has been noted that its preference is for loamy soils that have a mix of clay, sand, and nutrient-rich humus material. Generally, jack pine trees prefer acidic soil between 5.0 to 7.5 but can grow in some alkaline soils if the conditions are right.
These trees often do well in soil that has been ravaged by wildfires and are quick to spring up in the bare mineral soil.
Fertilizing
These trees grow where few other plants dare to—preferring the bare mineral soil of sites recently ravaged by wildfire. These trees thrive in low-nutrient soils, so it’s unlikely that you’ll need to fertilize the soil surrounding a jack pine tree. Cross this task off your to-do list if you plant a jack pine tree in your yard.
Pruning
The jack pine tree is known for its free-styling nature and tends to grow in a variety of directions. This wayward growth pattern gives these trees character and a unique look, so don’t expect to prune or shape it into the look of a conventional conifer.
In addition, these trees often retain their dead lower limbs for an extended period of time. You can lop them off, but it’s often not necessary to do so. If you do decide to clean up the lower extremities of your jack pine tree, do so in the spring before the sap starts running in the summer season.
Propagation
Cultivars, especially dwarf varieties, are often grafted and not suitable to be propagated. If you’re looking to multiply the species, the tightly sealed pine cones hold the key to propagation. Inside these cones, which can remain sealed for decades, are plenty of seeds that can sprout new jack pine seedlings. Choose pine cones that are mature, which is generally indicated by a change of color in the fall. Trees generally need to be 3 to 5 years old to serve as a seed source.
How to Grow From Seed
You can either start the seeds outdoors in the fall or in the early spring after a period of artificial cold stratification. Propagating jack pine trees from seed requires removing the seeds from the cones which in nature is done by heat, usually by a wildfire, to loosen the resin that holds the cone closed.
- Soak the cones in warm water for 8 to 12 hours, then leave them in the sun and wait for them to open. Remove the seeds.
- If not planting them outdoors in the fall, prechill the seeds for 1 to 2 weeks at 34 to 40 degrees in the refrigerator. Cold stratification aids germination.
- Plant the seeds ¼ inch deep in 4-inch pots filled with potting mix and keep them evenly moist. The seeds tend to germinate quickly.
- If more than 1 seed germinates, cut off any extra seedlings at the soil level. Let the seedling grow into a strong little plant before transplanting it into the landscape.
Potting and Repotting
Only dwarf varieties of the tree make good container plants. Choose a container with large drainage holes and fill it with a well-draining potting mix. Heavyweight planters work best as they are less likely to topple over. Terra-cotta works well because it wicks away extra moisture. Keep in mind that container plants need more watering than plants in the landscape. Container-grown trees also need winterization because the containers expose the roots to the cold. Insulate the roots by wrapping burlap or bubble wrap around the container, or create a planting silo by placing the container in a second, larger container.
Repot the tree in a larger container with fresh potting mix when the root system has reached the sides of the container, or the roots grow out of the drainage holes.
Overwintering
Jack pine is well-adapted to the harsh winters within its climate range and requires no winter protection.
Pests and Diseases
Pests and diseases can be an issue with these types of trees. The jack pine budworm attacks jack pines in the upper states around the Great Lakes and in the provinces of Canada every year. Other insects that cause damage to these trees include types of weevils, budworms, and beetles. Wild birds can assist with the control of some of these pests, but sometimes it might be necessary to use chemicals to eradicate them.
Young jack pines and seedlings are also prone to different kinds of root rot and fungus.
Keep your jack pine healthy by planting it in a location with full sun, giving it plenty of water during drought conditions.
IV. Uses and Benefits
Like other species of pine, Pinus banksiana has use as timber, although its wood tends to be knotty and not highly resistant to decay. Products include pulpwood, fuel, decking, and utility poles.
