The river birch (Betula nigra) is a medium-sized deciduous tree. Adaptable and attractive, the tree is best known for its strongly shredding bark, which peels off the trunk in thin layers of reddish-brown, cream and tan. While the river birch can grow on multiple trunks, it is most attractive and strongest when it is trained as a single-trunk tree, according to Edward F. Gilman and Dennis G. Watson, horticulturists with the University of Florida. The river birch is a hardy tree and requires only basic culture.
The river birch can be grown throughout most of the United States. In general, this tree thrives in United States Department of Agriculture growing zones 4 through 8. Most varieties grow best in hardiness zones 4b through 8. Some are cold-hardy enough to grow in zone 4a, while a few other cultivars, such as heritage, can grow in the subtropical conditions of 9a if they are well-irrigated.
Betula nigra can grow in full sunlight or partial shade. Plant the tree in a location where it will receive morning sunlight and afternoon shade if you live in one of the USDA warmer growing zones (8 or 9). Otherwise, locate the tree where it will be exposed to at least eight hours of sunlight per day, and preferably even more than that.
The river birch needs acidic soil or it will be choleric, which means it will not get enough minerals to produce good foliage. The leaves will turn yellow and may drop prematurely from the tree. Otherwise, the river birch can grow on just about any type of soil, whether clay or loamy, although it prefers loose, well-draining soil. This tree can tolerate periods of flooding, but do not plant it in an area where it will be underwater or in very soggy soil for most of the growing season, or it may contract root rot.
The river birch needs consistently moist soil. This is not a tree that you can let nature irrigate, unless you plant it near a riverbed or stream, or unless you live in a climate where you get regular rain showers. Maintain moist soil with regular waterings, especially during the tree’s first few years of life.
Insect Pests and Diseases
The river birch is one of the hardiest types of birch trees you can plant, according to a guide on the river birch published by the University of Illinois. It is highly resistant to the bronze birch borer and to Verticillium wilt. The tree is often short-lived (around 30 years at the most) in urban areas, but this is probably due to inadequate watering.