Learning to Grow: Consider site before planting a river birch tree

While this unseasonably wet summer isn’t ideal, some plant species are loving every minute of it. Tropical plants like hibiscus and cannas love the extra water and have shown their appreciation in beautiful ways.

One of the most popular trees in the garden center industry, the river birch (Betula nigura), especially loves this weather. Unfortunately for the river birch, this is unseasonal weather and we are still below the average rainfall for the year. And rainfall is just one of many factors that homeowners should take into account before planting a river birch. We receive many calls at the help desk about river birches each year. Here are some things to consider before you plant one.

With its cinnamon- or salmon- colored shedding bark and pyramid-shaped canopy, it is visually appealing for the home landscape. It is available both single and multi-stemmed and grows rapidly, approximately 24 inches per year, reaching 40 feet in 20 years.

Arborday.org promotes it as tolerant of most water levels, resistant to disease and borers and native to the United States, particularly the southern states mostly along the Mississippi River. They prefer acidic soil, below a pH of 6.5, and they can grow in loamy, sandy or clay soils.

As the name implies the river birch really does prefer moist to wet soil, ideally where the soil around it never actually dries out. As I describe the river birch’s high water needs, almost all homeowners promise to maintain a strict water schedule for such a beautiful specimen. But as they water they strip the soil of valuable nutrients that the tree needs in order to survive.  River birches frequently become chlorotic and need iron treatments to keep the leaves a lush green. This sounds easy enough until you try to treat a 20 foot tree, which can be costly.

Even though the description of the river birch states it is cold tolerant to zone 4, without a steady water supply the tree cannot function. The leaves will turn yellow or curl and dry up. The tree will start dropping leavings and branches may start dying. It is also susceptible to leaf blight – a fungus where the leaves turn yellow, then brown and the tree can lose up to 40 percent of its canopy. You can prevent blight by cleaning up your leaves every fall to prevent the spread of fungus. Alkaline soil is another major issue homeowners encounter with river birches so check your soil before you plant.

It is human nature to want what we can’t have and gardeners are no exception. River birches are a beautiful addition to any yard but consider the site and make an educated decision before investing in a tree. If your yard has low spots or flood areas, you may have found your ideal deciduous tree, otherwise consider other options.

• Jody Lay is a University of Illinois Extension master gardener for Kane County. The “Learning to Grow” column runs weekly during warmer months. Call the extension office at 630-584-6166 for more information.