Something about a birch tree's dark branches and slim, white trunks stir the imagination. Birch trees (Betula) are graceful, undemanding trees in the appropriate setting and can thrive for 30 years to 300 years. Some 60 different species of birch exist on the planet, but less than a dozen or so are common to North America.
Common Types of Birch Trees
It's not hard to pick a birch out of a lineup. They're known for their pale, papery, peeling bark marked with horizontal lines called lenticels. The trees grow to an average of 40 feet tall, but some shoot up twice that height, including the paper birch and yellow birch. Look for bright leaves that turn buttercup yellow in autumn and the small round cones that are the tree's fruit.
Both the paper birch (Betula papyrifera) and the water birch (Betula occidentalis) grow in the Pacific Northwest. Paper birch is known for its snow white, exfoliating bark, while water birch has mahogany or black bark. Paper birch is also called white birch and silver birch. One of the most common birch tree species in the Northeast is river birch (Betula nigra). Like water birch, river birch has reddish-brown bark that peels, while white birch's attractions include shining white bark and gracefully drooping branches. Yellow birch (Betula alleghaniensis), native to northern states, has straw-colored bark and can grow to 70 feet tall.
Caring for Birch Trees
Birch trees are tough native trees and require very little coddling. The trick is to get them planted correctly. Always keep the height and spread of the mature size of the tree in mind when planting. These trees grow faster than you might think.
Most birch species prefer slightly acidic soils, although a few species, like white birches, will grow in alkaline soils. Birch roots are extremely shallow, growing very close to the top of the soil. This makes them sensitive to heat and drought, which means that they grow best in shade. However, their leaves absolutely require sunshine to thrive. They grow best in a spot where the tree's roots are in the shade in the hot afternoons but the canopy still receives sun all day. Mulching the root area also helps to keep a birch's roots cool by regulating the soil temperature.
Common Birch Problems
All trees have some diseases and/or pests you have to watch out for. For birch trees, look out for the bronze birch borer, an invasive wood-boring beetle. Its larvae bore into the bark of weak or wounded trees, creating sap flow issues. Look for winding galleries beneath the bark. Prune out the branches in which you spot bronze birch borer signs.
Another bug that burrows into birches is the birch leafminer. It attacks leaves in late spring and early summer. You can see small spots that turn into brown blotches. The disease will disfigure the tree but usually isn't fatal. Similarly, aphids can suck the sap from birch leaves but won't kill the tree. Look for twisted, yellowing leaves. Ladybugs are predictors that can rescue your birches from aphids.