Paper Birch (Betula papyrifera)

Canoe Birch, Kenai Birch, Mountain Paper Birch, Paperbark birch, Paper Birch, White Birch

Paper birch (*Betula papyrifera*) is a tree with unique, papery white bark which is known to peel off the tree. It is also known as American white birch and canoe birch. This tree is relatively short-lived, and its wood is often used to make toothpicks, ice cream sticks, wooden bobbins, clothespins, and canoes.

I. Appearance and Characteristics 

Betula papyrifera (paper birch, also known as (American) white birch and canoe birch) is a short-lived species of birch native to northern North America. Paper birch is named after the tree’s thin white bark, which often peels in paper-like layers from the trunk. Paper birch is often one of the first species to colonize a burned area within the northern latitudes, and is an important species for moose browsing.

Betula papyrifera is a medium-sized deciduous tree typically reaching 20 metres (66 feet) tall, and exceptionally to 40 m (130 ft) with a trunk up to 75 centimetres (30 inches) in diameter. Within forests, it often grows with a single trunk but when grown as a landscape tree it may develop multiple trunks or branch close to the ground.

Paper birch is a typically short-lived species. It handles heat and humidity poorly and may live only 30 years in zones six and up, while trees in colder-climate regions can grow for more than 100 years. B. papyrifera will grow in many soil types, from steep rocky outcrops to flat muskegs of the boreal forest. Best growth occurs in deeper, well drained to dry soils, depending on the location.

  • In older trees, the bark is white, commonly brightly so, flaking in fine horizontal strips to reveal a pinkish or salmon-colored inner bark. It often has small black marks and scars. In individuals younger than five years, the bark appears a brown red color with white lenticels, making the tree much harder to distinguish from other birches. The bark is highly weather-resistant. It has a high oil content and this gives it its waterproof and weather-resistant characteristics. Often, the wood of a downed paper birch will rot away, leaving the hollow bark intact.
  • The leaves are dark green and smooth on the upper surface; the lower surface is often pubescent on the veins. They are alternately arranged on the stem, oval to triangular in shape, 4–10 cm (2–4 in) long and about two-thirds as wide. The leaf is rounded at the base and tapering to an acutely pointed tip. The leaves have a doubly serrated margin with relatively sharp teeth. Each leaf has a petiole about 2.5 cm (1 in) long that connects it to the stems.
  • The fall color is a bright yellow color that contributes to the bright colors within the northern deciduous forest.
  • The leaf buds are conical and small and green-colored with brown edges.
  • The stems are a reddish-brown color and may be somewhat hairy when young.
  • The flowers are wind-pollinated catkins; the female flowers are greenish and 3.8 cm (1+1⁄2 in) long growing from the tips of twigs. The male (staminate) flowers are 5–10 cm (2–4 in) long and a brownish color. The tree flowers from mid-April to June depending on location. Paper birch is monoecious, meaning that one plant has both male and female flowers.
  • The fruit matures in the fall. The mature fruit is composed of numerous tiny winged seeds packed between the catkin bracts. They drop between September and spring. At 15 years of age, the tree will start producing seeds but will be in peak seed production between 40 and 70 years. The seed production is irregular, with a heavy seed crop produced typically every other year and with at least some seeds being produced every year. In average seed years, 2,500,000 seeds per hectare (1,000,000 per acre) are produced, but in bumper years 86,000,000/ha (35,000,000/acre) may be produced. The seeds are light and blow in the wind to new areas; they also may blow along the surface of snow.
  • The roots are generally shallow and occupy the upper 60 cm (24 in) of the soil and do not form taproots. High winds are more likely to break the trunk than to uproot the tree.

II. How to Grow and Care

Sunlight

Paper birch prefers the partial shade conditions found along margins where other taller trees are growing, but it can grow acceptably if planted in full sun, especially in cooler climates.

Temperature and Humidity

This tree grows best in cooler climates and cool soil temperatures. Keeping the soil cool and moist by heavy mulching is a good strategy for trees that can’t be planted in a naturally moist location. Near the southern end of the hardiness range (zones 6 and 7), this tree sometimes struggles; it prefers a climate with long winters and coolish summers.

Watering

Newly planted paper birch can be sensitive to too little or too much water, so watering 30 seconds twice a week should be enough. The important thing to keep in mind is that the soil should be moist, which means not too dry or soaking wet. Once the tree is established, there is no need to water, except in a hot summer. In summer, lay a hose on the base of the tree and water in a mild stream, allowing water to slowly run over the root system.

Soil

Paper birch grows best in sandy or rocky loam soil that is fairly moist. It naturally favors acidic soil but will do fine in soil with a neutral pH, or even slightly alkaline.

Fertilizing

If the soil is alkaline or lacks certain nutrients, fertilize every spring and summer. Most species grow best in somewhat acidic soils with a pH value between 5.0 and 6.5. Slow-release fertilizer should be used. Fertilizer spikes are convenient and simple to use. However, you should fertilize only after a soil test determines that the substrate is lacking in nutrients.

Fertilize in early spring or summer, as this is the peak growth period when a tree requires the most nutrients. Avoid fertilizing the tree in mid-fall, as a late flush of growth may not harden before the winter and expose the young tissue to frost damage.

Pruning

Paper birch should not be pruned in late winter or early spring just before its dormancy period ends. This is because heavy sap flow and open wounds attract birch tree borers in their egg-laying season. Removing more than 25% of the total tree canopy will most likely result in tree death or seriously reduced growth, as with lost photosynthetic surface, the tree loses the ability to synthesize its nourishment. Also, removing too much of the canopy can expose the tree base and roots to too much sunlight.

Prune your paper birch in late summer or early winter. If performed properly, pruning is very beneficial, as removing dead or infected branches, closely growing branches, and branches protruding out of the canopy increases the overall health of the tree, reduces tree infections, and improves the aesthetic appearance. Remember to disinfe

Propagation

Although the success rate is usually only about 50 percent, birch trees can sometimes be propagated by rooting branch cuttings. Here’s how:

  • Cut a 6- to 8-inch-long green branch tip, making the cut just below a leaf node. Remove all the leaves from the bottom 3 inches of the cutting. Dip the cutting in rooting hormone, then plant it in a small pot filled with standard potting soil.
  • Cover the planting pot loosely with a clear plastic bag and place it in a bright location but out of direct sunlight. Keep the soil moist but not soggy for about eight weeks, until roots develop.
  • Transplant the rooted cutting into the desired landscape location, into a hole where the soil has been amended with peat moss and sand. Be careful not to break the young roots as you transplant the cutting into the ground.
  • Keep the soil moist but not soggy for the next eight weeks. At this point, if the planted cutting is developing new growth, you know that a successful tree is beginning to grow. The growing sapling can now be fed with diluted fertilizer.

How to Grow from Seed

Collect paper birch seeds in the fall, when the catkins start to brown. The seeds are small, with wings that help them fly on the breeze. Place the seeds in a small container filled with compost or humus. Cover the seeds with a thin layer of potting soil and sprinkle them with water.

Place the container in an area where the seeds can stratify, such as in a refrigerator or an unheated garage during winter. They need to be in the cold for six months.

After the six months are over, set the container on a sunny windowsill for light and warmth. The soil should be kept moist. The seeds should sprout within a few weeks. Thin out the seedlings until you have one strong contender. This can be planted in the ground in the spring after all danger of frost has passed.

Overwintering

A good layer of mulch underneath the tree will help it through the winter. Also, keep an eye on the water the tree is getting. Snowfall can often give a tree what it needs during the winter, but if you are facing a period of little to no snow, additional watering can help keep the ground moist.

Pests and Diseases

All birches can fall victim to the bronze birch borer, a devastating insect pest. An affected tree will show yellowing leaves that begin to shed, and the tips of the branches will turn brown. These symptoms generally start at the top of the tree and move downward. Paper birch is one of the more resistant of the birch species, but if bronze birch borer does strike your tree, prune off affected limbs as you see them, and use a pesticide designed to control the insects. Badly affected trees will need to be removed and replaced.

Aphids, birch skeletonizers, and birch leaf miners can also wreak havoc on trees that have become weakened due to drought. Make sure your trees are not competing with your lawn for moisture. Another potential drought problem is birch dieback, where the branches of the birch tree die out over time. Conversely, trees that are watered too much can become prone to fungal problems, including leaf spots and cankers.

III. Uses and Benefits 

  • Bark

Its bark is an excellent fire starter; it ignites at high temperatures even when wet. The bark has an energy density of 5,740 cal/g (24,000 J/g) and 3,209 cal/cm3 (220,000 J/cu in), the highest per unit weight of 24 species tested.

Birch bark is used in a number of crafts by various Native American tribes (e.g. Ojibwe). In the Ashinaabe language birch bark is called wiigwaas. Panels of bark can be fitted or sewn together to make cartons and boxes. The bark is also used to create a durable waterproof layer in the construction of sod-roofed houses. Many indigenous groups (Wabanaki peoples) use birch bark for making various items, such as canoes, containers, and wigwams. It is also used as a backing for porcupine quillwork and moose hair embroidery. Thin sheets can be employed as a medium for the art of birchbark biting.

  • Plantings

Paper birch is planted to reclaim old mines and other disturbed sites, often bare-root or small saplings are planted when this is the goal. Since paper birch is an adaptable pioneer species, it is a prime candidate for reforesting drastically disturbed areas.

Paper birch is frequently planted as an ornamental because of its graceful form and attractive bark. The bark changes to the white color at about 3 years of growth. Paper birch grows best in USDA zones 2–6, due to its intolerance of high temperatures. Betula nigra, or river birch, is recommended for warm-climate areas warmer than zone 6, where paper birch is rarely successful. B. papyrifera is more resistant to the bronze birch borer than Betula pendula, which is similarly planted as a landscape tree.

  • Wildlife

Birch bark is a winter staple food for moose. The nutritional quality is poor because of the large quantities of lignin, which make digestion difficult, but is important to wintering moose because of its sheer abundance. Moose prefer paper birch over aspen, alder, and balsam poplar, but they prefer willow (Salix spp.) over birch and the other species listed. Although moose consume large amounts of paper birch in the winter, if they were to eat only paper birch, they may starve.

Paper Birch (Betula papyrifera) Details

Common name Canoe Birch, Kenai Birch, Mountain Paper Birch, Paperbark birch, Paper Birch, White Birch
Botanical name Betula papyrifera
Plant type Tree
Hardiness zone 2a, 2b, 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a
Growth rate Fast
Harvest time Fall
Height 50 ft. 0 in. - 70 ft. 0 in.
Width 50 ft. 0 in. - 70 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color Brown/Copper
Leaf color Green