Cottonwoods: Wood as Strong as Cotton

Don’t let this happen to your property.

Last week, Seattle was hit by a particularly strong windstorm. My neighbors a few doors down have a line of cottonwood trees (Populus nigra, I think) at the front of their property. For the second time in two years, one of them blew over. I wasn’t surprised.

In the mid-20th century, cottonwoods were commonly planted as windbreaks. They grow rapidly and have tall, fastigiate forms. But the wood in cottonwoods is weak and they’re susceptible to canker and other diseases. They’re also short-lived for trees with a lifespan of 40-50 years. As they age, they drop a lot of branches and leaf matter. Plus, their appearance is messy. Up close, poplar trunks are gnarly (not in a pretty way) and twiggy sprays of branches sprout everywhere.

But because they grow like giant weeds, some species putting on six feet per year, they were planted often. You might see them along the border of a park or trail. The trouble is their form is like an old-fashioned, upside broomstick. Their crowns are susceptible to being pushed by strong winds. A high wind catches their top and poof, they fall over, either whole, as one did a couple of years ago, or snap off somewhere in the middle, as the one did last week.

Once one poplar in a line goes, the others become more exposed and more likely to blow over or break. So if you live in the Seattle area and have a poplar tree, think long-term and have it removed by a certified arborist. In our neighborhood, the trees have only taken out power lines, but depending on where a tree’s planted, it can take out much more: cars, roofs, fences. Plus, there are so many other prettier columnar trees to grow anyway–if you absolutely need a columnar tree that is. Fastigiate beech trees (Fagus sylvatica ‘Fastigiata’) are lovely and the variety ‘Dawyck Purple’ has deep purple leaves. ‘Dawyck Gold’ has golden foliage. Columnar Hornbeams (Carpinus betulus ‘Fastigiata’) grow in a tight strong form and have vibrant fall color. The Fastigiate Sweet Gum (Liquidambar styraciflua ‘Fastigiata’) is tough, tough, tough. Takes pollution and heat and has brilliant orangey red fall foliage.

I think my neighbor has three cottonwoods left. I’ll be watching in the coming seasons to see how they do during strong winds. Luckily, my house (as well as theirs) is out of falling range.

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