Birch trees can be a beautiful and productive asset on many landscapes. However, like most landscape plants, species have varying nutrient, light and moisture requirements and will only thrive on the right site with adequate care.
The river or black birch, Betula nigra, grow best as a multi-stemmed specimen. It can grow 40 to 70 feet tall and will have variable cream, brown or reddish brown bark or a combination thereof. River birch grows best in soil which retains moisture. The native variety is more resistant to bronze birch borers than other species.
For the most part birch species have interesting and attractive bark colors and textures ranging from pure white to mahogany and cream brown in between. Many popular landscape cultivars have papery looking bark which peels away naturally revealing color variations within a single tree. In the spring birches produce copious flowers which appear as pendulous catkins, and fall brings brilliant, yellow hues in foliage. Usually they are small to medium sized trees with an upright habit, although there are “weeping” varieties.
Smaller growth habit cultivars can be used as specimen trees on cozier landscapes. And because birch canopies are, on the whole, not very dense and so do not cast a lot of shade; these can easily be planted in and among other beds and plantings without causing damaging competition. Many varieties grow as multi-stemmed trees or can be planted in clumps to give that appearance. Beautiful bark varieties give birch trees interest even throughout the winter.
Paper birch, Betula papyrifera, will have pure white bark, which begins naturally peeling away, do not assist with bark peeling. They can grow to be 50 to 70 feet tall and may grow as multi-stemmed plants or in clumps. These trees will not do well in urban environments or other areas with poor air quality or pollution. Native paper birches are less susceptible to the bronze birch borers than the European birch.
It is best to plant birch species in the spring, some may be slow to get established and will need as many growing degree days as possible. Make sure to choose a site with deep, rich, moist but well-drained soil that is slightly acidic. Most birch varieties will enjoy a site in full sun, but acoid very hot, dry urban settings. Have your birch trees pruned by professionals when and if needed, poor or improper pruning can lead to health issues and decline.
Unfortunately, birch species are susceptible to the bronze birch borer and birch leafminer. They can be affected by many other pests or diseases but the aforementioned two are the most common. Your arborist can assist you with cultural or preventative measures to protect your trees and also develop and implement a management plan should control become necessary. Chlorosis can result in birch trees planted where the pH is too high. If soil conditions change and an established tree becomes chlorotic, your arborist can test the soil and/or prescribe a treatment plan including soil amendments to lower the pH to 6.5.
