How To Plant and Grow a River Birch Tree
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The river birch tree supplies excellent summer shade, beautiful foliage spring through fall and a stunning winter display. Here's how to grow one.
Most ornamental trees are valued for their spring and fall foliage displays, but offer little aesthetic value during the winter. Not the river birch tree. The river birch’s beautiful bark offers year-round beauty along with gorgeous foliage spring through autumn.
While these features apply to most birch trees, the river birch has an advantage as one of the hardiest varieties. It can grow in most regions of the U.S.
What Is a River Birch Tree?
The river birch (Betula nigra) is a fast-growing, deciduous shade tree that’s prized for its rapid growth, environmental resilience and ornamental value. It has arched, drooping branches with oval-shaped green leaves and serrated edges.
In late summer and fall, river birches produce attractive reddish-green flowers (catkins) on the end of the branches. The most stunning feature of the river birch is brilliant white bark that peels back in thin layers (also known as exfoliates) to reveal a salmon-colored inner bark. When the tree drops its leaves in the winter, the bark offers an ornamental centerpiece in the landscape.
Where Do River Birch Trees Thrive?
As the name implies, a river birch’s native habitat is near river banks, so they prefer moist soil. However, they can tolerate drier soil as the tree matures and the roots become well-established. This makes mature river birch trees relatively drought-tolerant which is unique among birch varieties. The river birch prefers acidic soil, and can develop iron deficiency if the soil’s pH is above 6.5.
Common Pests and Diseases
River birch is generally more resilient to pests and diseases than other varieties of birch. However, it is still prone to the following:
- Bronze beach borer. A roughly 1/2-inch-long, bronze- and black-colored beetle that bores into a tree’s bark to feed on the cambium layer. Common signs of infestation are yellowing and thinning foliage beginning at the upper canopy, and D-shaped holes in the trunk where the insect bored into the bark.
- Birch leafminer. Roughly 1/8-inch-long, black insects that closely resemble flies. Their larva feeds on the leaves’ green tissue and causes a partial to full browning of the leaves.
- Birch dieback. A disease that causes the branches in the upper canopy to die off. It can be caused by a fungal infection or a bronze beach borer infestation.
- Anthracnose leaf blight. A fungal disease that initially produces brown spots on the leaves until they curl and die back completely.
How to Care for a River Birch Tree
- Water. Water deeply once or twice a week to keep the soil and roots moist. Maintaining moist soil is especially important during the tree’s first couple years of growth, and during the hot summer months.
- Mulch. Apply a two- to four-inch layer of mulch around the tree’s base for moisture retention.
- Fertilize. Apply a fertilizer formulated for acidic soil as the first leaves start to unfurl in the spring. Prevent iron-deficiency in alkaline soil by providing an iron amendment
- Test the soil. Test the soil’s pH every two to three years. Add a soil acidifier to lower the pH if it’s above 6.5.
- Control pests and diseases. Inspect the tree periodically and eliminate any pests with insecticide or predator insects like lady beetles or pirate bugs. Prune back diseased branches, or use a fungicide for severe infections.
How to Prune a River Birch Tree
A river birch tree can grow between 40 and 70 feet tall and can grow up to 13 to 24 inches per year. Annual pruning promotes healthy and attractive growth.
The best times to prune river birch are during late spring, late fall and winter. Pruning in the spring before the first leaves emerge will cause the tree to lose sap, and fresh pruning cuts can attract birch borers in the summer.
- Remove stems or branches growing out of the trunk or around the base of the tree (AKA suckers).
- Remove diseased branches as soon as they’re discovered, regardless of the time of year. Sterilize the blade of your cutting tool between cuts to prevent disease spread.
- Remove dead branches.
- Remove branches that are rubbing against each other.
- Trim back branches that are closer than two inches apart to promote airflow through the canopy.
- Trim back branches that detract from the desired appearance and balance of the canopy.
How to Propagate a River Birch Tree
Propagating from seeds
- River birch seeds can be harvested from catkins in late spring when they start turning brown. Place them in a dry location inside a paper bag for three to four days, or until the seeds naturally separate from the fruit. After the seeds are collected, they should be planted immediately for best results.
- Sow a thin layer of seeds in a tray filled with soilless growth media.
- Place in a protected area with indirect sunlight.
- Water seeds twice a day until the seeds germinate and sprouts form. This usually takes four to six weeks.
- Transfer to a nursery pot filled with potting soil mix after the second set of leaves have formed, typically two to three weeks after germination.
- Keep the soil moist by watering two to three times a week. Keep in a protected area until the following spring.
- Transplant the saplings outdoors after spring’s last frost, after acclimating them by setting the pot outside in direct sunlight for about a week.
Propagating from Cuttings
- Fill a small nursery pot with a soilless media.
- Cut a six- to eight-inch-long section off the tip of a branch, just below a spot where a leaf meets the stem (leaf node), at a 45-degree angle. Place in the potting mixture.
- Place the pot on a heat mat in a protected area with indirect sunlight.
- Mist the cutting twice a day. River birch cuttings require mist to successfully root.
- After about six weeks, check for root development by gently tugging on the cutting and feeling for resistance.
- Transfer to a larger pot filled with potting soil after the roots have formed.
- Keep the pot in the protected location until the following spring, then transplant into the ground after the last frost