When most people think about birch trees, the attractive white bark common in many varieties probably comes to mind. The trees embellish landscapes with their graceful and stately habit and their fine-toothed foliage brightens landscapes with a blast of fall color. Grown in proper conditions, birch trees make an elegant specimen that can live for an average of 50 years.
Common Birch Tree Types
Birches are quick-growing and short-lived deciduous hardwood trees belonging to the genus Betula and commonly found in temperate regions of the U.S. They are small to medium-sized trees averaging around 50 feet tall. All types produce similar thin serrated foliage which turns a bright yellow in the fall, and produce long female and male catkins in autumn, which turn into tiny winged seeds. Depending on the type, bark is peeling or non-peeling and ranges in colors of white to salmon-colored. Gardeners desiring to add a birch tree into their landscapes are most likely to find the types listed below.
Hardy in USDA zones 3 through 6, paper birch (Betula papyrifera) has distinctive white, peeling bark on mature trees and is a brownish color when young. Native to northern portions of the U.S., the tree averages around 50 feet tall with a width about half the tree's height. It makes a suitable single-trunk specimen with a high tolerance to cold weather.
River birch (Betula nigra) tolerates warmer conditions than other birch varieties, hardy in USDA zones 4 through 9. The southeastern native has salmon-colored peeling bark and averages around 50 feet tall with a width of about 25 feet. As the name suggests, river birches tolerate and require a moist site for proper growth with acidic soil conditions. The tree is a useful specimen in landscape locations that are wet.
Considered a smaller birch tree, gray birch (Betula populifolia) is a North American native hardy in USDA zones 4 through 6. The tree grows approximately 30 feet tall and 20 feet wide at maturity and produces brown bark while the tree is young, giving way to white, chalky bark that doesn't peel once mature. Gray birch trees are more tolerant of dry soils than many of their relatives and make a handsome short-lived specimen.
Purchasing a Birch Tree
When shopping for a birch tree to purchase, you want to look for one that is healthy with no signs of disease or pests, which generally show up as distorted foliage or leaves that are yellow or spotted. You also don't want to purchase a root bound tree that has the roots growing out of the bottom drain holes of the container, as it might not perform well once planted.
If purchasing a birch tree from a local nursery or a native plant seller, you will generally find trees that are one year old or younger, as these are fast-growing trees that quickly reach their mature height. Many online plant dealers sell birch trees and ship while the tree is in its dormant state. Online plant dealers selling various birch tree types include Nature Hills.com, Fast Growing Trees and Tennessee Wholesale Nursery.
Landscape Uses and Site Selection
Select a permanent site in the landscape that allows the tree to reach its mature height without interference from power lines or structures and where its sensitive root system isn't disturbed. Therefore, planting a birch along a driveway or walkway where the soil becomes compacted with use isn't advised. Because the tree's roots will grow toward and under a house's foundation, plant well away from the structure so damage doesn't occur.
With their distinctive bark and colorful autumn foliage, all types of birch trees make striking specimens in the landscape. They work well used in native and woodland gardens and river birch trees are eye-catching additions to streams or ponds. Their characteristic bark adds interest when planted with dark-colored barked trees such as oaks. Since they drop their leaves in the fall, consider planting in a location where the fallen foliage won't create a mess.
Preferred Growing Conditions and Planting Considerations
For birches to thrive in a home landscape it's important to plant and grow them in a site with preferred conditions. They can be fussy when it comes to their environment, but gardeners can alleviate these potential problems by following proper cultural practices.
Cool, Shaded Spots Are Best
When growing in its natural forested conditions, birch trees thrive in moist soils that are cool. Their root systems are shallow, which makes them quite sensitive and they grow poorly in soils that are hot and dry. In the home landscape, gardeners should plant the birch tree in a location that receives partial to full sun, but where the soil is fertile, moist and shaded from the sun to retain its coolness. Generally, the eastern and northern side of the home has the most shade during the afternoon and helps retain the soil's moisture and coolness.
Soil and Moisture Retention
Birch trees grow best in acidic soils with a pH level between 5.0 and 6.5 and won't perform well in soils that are too alkaline. With alkaline soils, it's hard to maintain acidic conditions over the life of the tree, so it's best to do the initial planting in naturally acidic soils. If you are unsure of your soil's pH in the location you've selected to plant the birch, you can purchase an inexpensive soil pH tester and test the area before planting.
Though all birch trees prefer soils that retain moisture, if the planting site has a tendency to flood or remain soggy, you will have the most success growing a river birch in constantly wet locations.
Birch Tree Maintenance
Proper cultural practices such as watering, fertilizing, pruning and mulching play important roles in the development and maintenance of a healthy growing birch tree. The most important of these practices are watering and mulching, as both create a cool and moist environment, which the tree requires to thrive.
Aside from mulch having an aesthetic benefit, applying mulch under the birch tree keeps the soil moist by conserving water and cool during summer by regulating the temperature. It also adds organic matter to the soil as it breaks down, helps with soil compaction and reduces unwanted growth from weeds or grasses. Having a mulched area under the tree's canopy also reduces the possibility of lawn equipment damaging the trunk, which opens the tree up to pest and disease problems.
Organic mulches, such as wood chips and compost made from shredded leaves or shredded bark, work best applied under the birch canopy. Light-colored stones reflect the sun's heat and can heat up the soil, and the stones can make the soil more alkaline, all of which negatively affect growth and health. When applying the mulch, use a 3- to 4-inch layer spread evenly over the planting site. Keep the mulch from butting against the trunk as it can create disease problems.
Adequate water is necessary during the growing season for birch trees to grow well. The easiest way to apply water is to place a hose on the planting site turned on low and allow it to trickle over the soil for several hours to make sure it saturates the root system. If weather conditions are dry, apply water to the birch weekly. When fall approaches and to prepare the tree for winter, cut back water applications to once every two weeks.
Fertilize birch trees with an annual application of a slow-release blend containing nitrogen and potassium. Follow package directions on amounts and spread the product evenly under the tree's canopy being sure not to butt the fertilizer against the tree's trunk. If you feel the tree is suffering from a nutrient deficiency, you can do an at-home soil test to determine what specific nutrients are lacking. If the soil becomes compacted or suffers water runoff, the tree may require an application of phosphorus and a soil test will determine this. After applying fertilizer to the area, always water it in well to the soil to avoid burning the tree.
All types bleed when pruned, especially during late winter through early summer when the tree bleeds excessively. Therefore, perform any pruning cuts during late summer and early fall. The bronze birch borer, a damaging pest for many varieties of birch trees, also takes flight in early May through August, so if there are pruning needs during this time, be sure to treat the cut areas with an insecticide to prevent an infestation.
Prune young trees to create a strong structure by removing crossing, weak and damaged branches. Never prune away more than 25 percent of the tree's canopy as it opens it up to excessive light penetration, which creates more heat to the soil and creates a loss of moisture. Prune off dead or diseased branches anytime throughout the year, making your cut into green sections of wood.
Pest and Disease Problems
Providing birch trees with their preferred cultural requirements like water, fertilizer, and soil conditions, and not injuring the tree's bark with lawn equipment produces healthy trees that are not prone to disease or pests. However, some pests and diseases could still cause problems, which are usually cosmetic to these sometimes-finicky trees.
Common insects infesting birch trees include aphids, webworms, and leaf miners. The pests cause leaf curl and brown spots and unless the pest population is large, usually don't require treatment. In the event of a heavy infestation, products such as Bt or spinosad work well in controlling the pests and are safer for the environment. Always apply the products late in the afternoon when conditions aren't sunny.
Bronze Birch Borer
The most serious pest that can kill a birch tree is the bronze birch borer. However, native birch trees, such as the gray and paper birch, are relatively resistant to a borer attack. The borer does not affect river birch trees. To reduce possible infestations in gray or paper birches, maintaining good cultural conditions by planting in a proper site with preferred soil conditions and keeping the tree properly watered and fertilized cuts down on the possibility of the bronze birch borer.
Bronze birch borers average around ½-inch long and are dark brown with a bronze appearance. They infect birch trees in May laying their larvae under the bark, which creates tunnels as they feed on the phloem of the trunk and hatch into adults in springtime. Adult beetles only cause cosmetic damage as they eat the foliage, but the larvae disrupts the tree's ability to transport water and nutrients and if not treated in the earliest stages, lead to the tree's decline and eventual death.
The birch tree shows signs of an infestation by the canopy slowly suffering dieback until the entire tree is dead. Treatments are effective if done at the first sign of the pest. Use a product containing bifenthrin or permethrin and saturate all portions of the tree. If the tree is large, you may have to call in a professional to reach all areas.
As with pest problems, the best way to prevent diseases is keeping the tree healthy. Leaf spots and cankers cause cosmetic problems and some branches may die and lose foliage. Treat by pruning away the affected portions of the tree, and rake up and dispose any fallen foliage.
The Beauty of a Birch
By selecting the right birch tree for your climate and conditions, it will grace your landscape with its splendor for years. It might be a little prissy with its requirements for care, but the attractive bark, elegant habit and addition of color during autumn makes it worth the extra attention.