River birch prefers consistently moist acidic soil and at least six hours of full sun.
It tolerates warmer temperatures than other birch species, growing to about three feet per year.
Soil
This tree is best planted where the soil is consistently moist or can be watered frequently.
The Spruce / Evgeniya Vlasova
The soil should have a pH between 5.0 to 6.5 for best results.
Iron chlorosis may affect the tree and cause yellowing leaves if it is not within this range.
It has good tolerance for dense, poor-draining soils.
The Spruce / Evgeniya Vlasova
This means a good soaking of 2 inches or more.
This tree needs damp soil and will suffer during periods of drought.
A thirsty tree is more likely to suffer insect or disease problems.
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Adding mulch will help keep the soil cool, which will protect the roots from drying out.
Do not place mulch where it will touch the trunk.
Still, river birch performs better in regions without blistering summers, and warm climates may shorten its lifespan.
The Spruce / Evgeniya Vlasova
This tree prefers humid weather over dry climates.
Fertilizer
Fertilizer is only needed if the tree shows signs of distress.
Where soil is too alkaline, feeding with an acidifying fertilizer may be useful.
The Spruce / Evgeniya Vlasova
For the amount to use, follow the product label instructions.
The native species grows about 60 to 80 feet at maturity and about 40 feet wide.
Several named cultivars of river birch offer some improvements over the native species.
SEWilco / Wikimedia Commons / CC BY-SA 3.0
Dwarf varieties may grow slower, taking 10 years or so to reach 10 feet.
Pruning
River birch is a self-pruning tree.
it will easily shed branches that are diseased or unhealthy, making it require very little maintenance.
If you are pruning, river birch is best pruned in fall and winter.
Avoid early spring pruning while the tree’s sap is running.
Leave at least 75 percent of the tree intact when pruning.
Branches that rub together should be removed.
Also, remove branches that grow straight up from the trunk, as these have a weak attachment.
Catkins are the flower clusters that contain the fruit, or in this case, nutlets.
The nutlets are the seeds.
Overwintering
River birch generally overwinters without incident when planted within its established hardiness range.
However, these thin-barked trees can be susceptible to gnawing from rabbits and other animals.
Occasional issues with aphids or fungal leaf-spot diseases may occur but are rarely serious.
The tree almost always returns to a regular cycle when environmental conditions stabilize.
Bloom Months
River birch is amonoecious treecontaining male and female flowers on the same trees.
River birch produces male catkinscompact, closed flower clusters from August to October.
It also forms female catkin flowers in the spring during April and May.
Bloom for both catkins occurs in the spring when the female catkins appear.
What Do River Birch Tree Flowers Look and Smell Like?
The male flowers are brown, drooping catkins, while female catkins are smaller and upright.
The flowering clusters offer no fragrance.
Although not particularly colorful, the dangling catkins do offer some winter interest.
When problems occur, it is usually because the tree has been planted in less-than-ideal circumstances.
Soil amendments or fertilizing with an acidifying fertilizer may rectify this.
Leaves Are Puckered, Distorted
This is often a symptom of an aphid attack.
But this is not a fatal problem; the tree will quickly recover.
River birches are not particularly long-lived trees.
River birch is an excellent choice as a specimen tree.
The salmon-red peeling bark will provide color throughout all of the seasons.
This tree works well in locations with wet soil, such as along ponds and streams or low-lying spots.
Dwarf varieties can be used in rain gardens or even as foundation plants.
Betula Nigra.Missouri Botanical Garden
River Birch.Clemson Cooperative Extension.
River Birch Betula Nigra.
Wisconsin Horticulture Division of Extension
Plant Propagation by Stem Cuttings.
North Carolina State Extension
Dirr, Michael.Manual of Woody Landscape Plants.
Stipe Publishing, 1998
River Birch.
Ohio Department of Natural Resources
River Birch, Betula Nigra.Wisconsin Horticulture Division of Extension.
