Stately and huge cottonwood trees are found throughout many regions of North America. If your yard needs shade in a hurry, this attractive tree may be the ticket. Learn how to identify, plant, grow, and care for cottonwood trees.
About Cottonwoods
Eastern cottonwood, Populus deltoides, is a member of the willow family native to North America. Botanically speaking, a cottonwood tree is a type of poplar tree.
It’s typically found in low areas alongside streams, rivers, and lakes. Native American tribes used its trunks to make canoes and the bark for medicinal tea.
They are huge trees, reaching 70 to 100 feet in the air, with trunks commonly four feet wide or more. And if you’re looking for a fast-growing tree, this is it. Cottonwoods can put on 5 or 6 per year, making them the fastest growing trees in North America.
The bark of an Eastern cottonwood tree. Credit: Aleksandra Duda
Rapid growth does come with problems, namely reduced strength. Cottonwoods often lose a branch during storms or heavy winds, and while they aren’t short-lived like some hybrids, they commonly live to be about 80 to 100 years old, although some get much older.
Eastern cottonwoods are quite cold-hardy and can be planted in USDA zones 2 to 9.
How to Identify Cottonwoods
Cottonwoods can be identified by their form and leaves. In terms of form, the tree is huge, with wide and spreading branches that give it a sculptural look for architectural interest, especially in the winter. The twigs are stout, gray-yellow in color.
The leaves are large, simple, and triangular-shaped with a notched margin and a sharp point. They grow in an alternate pattern on flat stems, and the foliage rustles attractively in the breeze, adding shimmering beauty and a lovely sound. In autumn, their foliage turns a beautiful golden yellow.
Cottonwood trees are female or male. The female trees product the cotton seen here.
The cottonwood name refers to the cottony substance attached to the seeds. However, it’s only female trees produce cotton; you can buy either a male or a female tree.
Cottonwoods are commonly purchased as bare-root seedlings or established stock in nursery containers. Bare-root cottonwoods should be planted as soon as possible after receiving them and do best when planted in the spring while the trees are still dormant.
Containerized cottonwoods may be planted at any time during the growing season. While spring planting is favored in northern areas, as long as they’re in the ground a month before the first frosts, they’ll have time to establish new roots before winter.
Where to Plant Cottonwood
Select a site with full sun. Cottonwoods will also grow in partial sun, but the brighter, the better for these trees. They aren’t picky about soil type and will grow in most soils as long as they aren’t constantly waterlogged. While neutral pH is ideal, cottonwoods will grow in a wide range of soil conditions.
Cottonwoods grow fast and large and frequently shed branches in storms. Avoid planting them where a future falling branch could cause damage. They are great shade trees, so don’t plant them where they’ll cause problems in your garden as they increase in size.
How to Plant a Cottonwood Tree
Remove all sod and debris from the spot.
Dig a hole the same depth as the root ball and at least twice as wide. The hole should resemble a shallow bowl, not a well. Keep the excavated soil handy.
Loosen the soil around the edges and bottom of the hole. Hard compacted soil will make it difficult for new roots to penetrate (or water to drain).
Remove the cottonwood tree from its container and prune any circling or girdling roots. Rootbound plants benefit from scoring the root ball to stimulate new growth outwardly.
Test fit the cottonwood in the hole. Check for depth and ensure no roots are bent over or circling the hole.
Backfill the hole with the native soil you removed, keeping the tree vertical while filling. Tamp the soil firmly around the roots to remove air pockets, then give it a good drink of water. Continue filling the soil around the roots and firming it with your hands.
Mulch around the tree, about 3-4 inches thick. Spread the mulch evenly in a circle extending 2 feet from the trunk. Don’t allow the mulch to touch the tree–keep an inch or two of space.
Growing
How to Grow Cottonwoods
Cottonwoods are quite happy to take off without a lot of help from you. However, some supplemental watering during the first year will help them establish. If you are planting a specimen tree in the yard, a deer exclosure around the young tree will help it avoid being lunch or a scratching post.
Fertilization of cottonwoods is unnecessary. Choose a spot with full sun and loamy soil, and it will grow just fine.
How to Prune Cottonwoods
Pruning young cottonwoods is only needed to remove dead and broken branches or to shape the tree for aesthetics. Cottonwoods can be pruned at any time of year.
How to Propagate Cottonwoods
Eastern cottonwoods can be propagated by collecting fresh seed, which germinates rapidly. However, they are most commonly (and easier, in my opinion) propagated with cuttings.
During winter, take cuttings of small-diameter stems from last year’s growth. The cuttings should be about a foot long and have a terminal bud.
Wrap cuttings in plastic wrap to keep them from drying out and store them in the refrigerator.
In early spring, stick cuttings in moist potting soil or damp sand, burying all but the top couple inches with the bud.
Keep moist but not soggy, and wait for new growth!
Types
As discussed above, if you’d like to avoid the mess of “cotton” blowing around in the yard and clinging to your laundry line, car windshield, and window screens, then plant only male trees. The females make the cotton-covered seeds disperse in the wind.
Eastern cottonwood (Populus deltoides): grows in eastern U.S. and southern Canada
Black cottonwood (Populus balsamifera): grows west of the Rocky Mountains
Fremont cottonwood (Populus fremontii): grows in California and Southwest
Gardening Products
Wit and Wisdom
Cottonwood’s proclivity to sprout from cuttings makes it a common choice for stabilizing waterway banks to prevent erosion. Thousands of cuttings are stuck in the soil like a forest of sticks, and they take right off.
Andy Wilcox is a flower farmer and master gardener with a passion for soil health, small producers, forestry, and horticulture. Read More from Andy Wilcox