Why Poplar Trees Are Invasive (What To Do If You Have One)

Poplar trees are some of the fastest-growing, most popular shade trees in America. They encompass some 35 species, not including a massive number of hybrids, and can be found in zones 3 through 9. One question many homeowners want to know is, are poplar roots invasive?

Poplar trees are invasive because they have an extensive, fast growing, and shallow root system (up to three times wider than the tree is tall) which can lift sidewalks, retaining walls, and clog pipes. Poplar roots send up suckers 100ft away from the base of the tree while spreading seeds rapidly.

Unfortunately, removing them isn’t quite straightforward. Before you plant any poplar trees in your landscape, read on to find out if you truly want them in your yard and what to do if you have one!

What Are Poplar Trees?

Poplars are part of the Populus genus and represent around 35 different trees including aspens and cottonwoods. They are fast-growing, good-looking trees that can get quite large. You may see them in parks and lining city streets because they grow so quickly and fill out to create a vast amount of shade.

They have triangular to rounded leaves that are often white on the undersides. Their bark can range from white to grey, to black making them very attractive trees.

Some of the most popular types of polar trees include:

• Japanese poplar
• Quaking aspen
• Big-tooth aspen
• Lombardy poplar
• White poplar
• Black poplar
• Willow-leafed poplar
• Eastern cottonwood
• Grey poplar
• Freemont cottonwood
• Canadian poplar

Though often called a tulip poplar or yellow poplar, this tree is not part of the Populus genus. The tulip tree is part of the Magnolia family. 

Poplar sizes can range from 20 feet at maturation to over 160 feet tall. Their canopies can get as wide as 70 feet in diameter. These fast-growing trees have short lives for trees though, even with immaculate care, they only live for about 50 years. 

Because these trees grow so fast they are often utilized in commercial applications. According to the University of Tennessee Agriculture Extension, because of their rapid growth, hybrid poplar trees are used in fiber farms and used for pulp and paper production.

Did you know poplar trees are commonly used to make paper products. If you are interested, read more in our article on 9 different trees that are used to make paper!

Why And How Poplar Trees Can Cause Issues

Imagine a poplar tree that’s over 100 feet tall with a 50 feet wide canopy. Now picture the root system growing underneath it. Did you picture something nearly the length of a football field?

That’s how large some poplar roots can grow. The roots can extend up to three times as long as the tree is tall and they stay in the shallows of the soil. Poplar roots seldom grow deeper than two feet deep.

These shallow roots will lift up sidewalks in their search for water. They can crack and lift driveways, mess up retaining walls, and if your foundation has any cracks or minute fissures, these roots can make their way in.

Once they get into these little cracks, the roots start to grow wider, causing bigger splits and problems. While these roots can’t typically get into modern plumbing pipes, if there are any leaks or weak spots that ooze water, know that poplar roots will seek them out.

Why Are Poplars Still Popular Trees?

Despite being so invasive and having massive roots that can cause a ton of problems, poplars are still planted all over the place. These trees have gained popularity because they grow so fast.

In the right conditions, some species of poplars can grow between five and eight feet a year. At around 12 years old, some of these trees are already full-grown and begin flowering and spreading their seeds.

These trees have attractive white, black, or grey bark that still looks good even in winter, so many people choose them for the eye-pleasing aesthetic. When you add in the exceptionally fast growth rate, you have a popular tree that many people want, until they start having problems with them.

The fast-growing habit of these trees makes them perfect for windbreaks and effective at controlling soil erosion. Often they are planted along large flat areas of cropland or grazing areas for cattle, to protect them from heavy wind damage.

Despite this popularity, poplar trees don’t make great landscape trees because of the problems the roots can cause and other problems that can come with them.

Poplar trees on the whole are susceptible to fungus that can cause the entire tree to lose its leaves in late summer. This causes the tree to become even more stressed and then it can invite a host of insect invaders that can help to finish it off.

The worst problem poplar trees can get is canker. This issue can’t be cured and it can spread to other trees. Poplar trees are very susceptible to canker; once contracted, they will perish in a matter of a few years.

Even though they are popular, many people consider poplars to be one of the ugliest trees.

Here’s Why Poplars Are So Invasive

Invasive plants are considered non-native species that tend to spread at an alarming rate. This label is typically attached to plants that get introduced from other areas. Invasive, non-native plants often don’t have many natural predators to keep them in check either.

The Maine Department of Agriculture, Conservation, and Forestry recounts how white poplars can be incredibly invasive. The roots can create suckers over 100 feet away, where dense colonies can be formed. Even fragments from stems and roots can regenerate the tree.

Male white poplars are rare, but female trees can be wind pollinated by other poplar species resulting in male, female, or hermaphrodite trees that can produce copious amounts of viable seeds.

Poplar trees have more than one way to procreate. They send out a lot of seeds that can travel distances and establish themselves, they can send out suckers from their roots, and they can regrow even if they are cut down. All these reasons make poplar trees and their roots invasive.

Poplar Trees Undergo A Constant Growth Spurt

Poplar trees are some of the fastest-growing trees out there. This can make them very invasive because they will outgrow other species of trees and shade them out.

Many young trees need a lot of sunlight to become established, but when a poplar is nearby it will quickly outpace most other trees.

Their massive, shallow root system can make it hard for other trees to grow around them. Other tree roots that reach deeper than poplars won’t get much water because poplar trees will absorb it all before it can reach the lower trees. 

Poplar Roots Send Out Suckers

Suckers are appendages that grow on trees—typically near the base—in an attempt to grow more branches.

These usually start after the tree has suffered some kind of damage. In poplar trees, they can send out suckers from their roots and start new trees, as well as from the base of the tree. 

It’s easy for poplar trees to grow a cluster of trees from a few suckers. Given how fast they can grow, and how far the roots can spread, these trees and roots can become invasive.   

Poplar Seeds Can Spread Over 20 Miles

These trees can send out millions of seeds every year. You’ve probably seen them floating by before but just haven’t realized it. They look like thin, ethereal balls of fluff floating on the slightest breeze.

A single cottonwood tree—which gets its name because of the clusters of fluffy seeds—can release 25 million seeds in a single season. Luckily the vast majority of these seeds never grow into new trees, but each one that does will mature in about 10 to 12 years and start adding to the fluff floating in the wind.

Poplar seeds are only viable for a week to two weeks before they are no good. They need to land in a damp, sunny, soft-soiled area to get started. Once they find that perfect patch of dirt they can grow very fast, up to a quarter of an inch in a single 24-hour period.

The fluffy tendrils that stick out from the tiny poplar seeds can cause them to float on the lightest breeze. In a good wind, they can travel 20 miles away.

If they happen to land on the water they can also float until they reach some wet ground in which to germinate.

This seed dispersal, though most don’t make it, is one reason poplar trees can be so invasive.

Poplar Stumps Can Regrow New Trees

Another habit that makes this family of trees invasive is how the stumps can regrow new trees. When poplar trees are cut down, the tree immediately starts growing suckers that can quickly grow into a whole new tree or a clump of trees.

If these suckers are left alone, you could have a new set of poplar trees in a few short years. So, whenever you cut down a poplar tree, you’ll have to do something with the stump if you don’t want it to grow back.

Poplars Are Masters Of Cross-Pollination

Another reason these trees are considered invasive is because of the ease with which they cross-pollinate.

Poplar trees are either male or female versions, but they are concerned with little else when it comes to creating viable seeds.

With this ease of cross-pollination, poplar trees can make countless varieties and easily produce more seeds to spread across the lands. If that doesn’t spell invasive, I don’t know what does.

Poplar Trees Can Grow Almost Anywhere

Most invasive trees don’t particularly care what kind of soil they grow in. Poplar trees fall into that category. While they do prefer moist, well-drained soil, they can adapt to most soil conditions.

The main thing poplar trees need when looking for a place to “set down roots” is water. They do need adequate watering, especially when they are getting established, once they reach maturity, that matters less and less.

When they have such a shallow, expansive root network these trees can drink up massive quantities of water even after light showers.

Ideal conditions for poplar trees are found among riverbeds and low-lying areas that trap water. Southern regions of the United States are prime areas for poplar trees to grow.

If you’d like, here are our top shade trees for small yards for some poplar alternatives.

What Can You Do With The Poplar Tree In Your Yard?

After reading all this, you may be thinking about getting rid of any poplar trees on your property. Since they are so invasive and able to grow back even when you have them cut down, what can you do?

That single poplar way in the back of the field could be left alone if you choose. It’s an option, but if it’s near any structures or anything they can damage, you might want to get it removed post haste.

And of course, if it’s sending out suckers or spreading via seed production, you’ll probably want to get rid of it. 

Poplar trees that are fixtures in your yard or set up as landscape features might need to be taken down.

There may not be any issues with the tree at the moment, but it doesn’t take long for them to show. The decision on whether to keep it or remove it rests in your hands.

If you decide to get rid of the poplar trees in your yard, the sooner you get started the better.

Deal With The Poplar Stump

If you decide to get rid of your poplar tree, reach out to a professional tree company to cut it down for you. While you are talking to them and scheduling a time to have it removed, schedule them to add in stump grinding. 

When the poplar stump is ground down it prevents the tree from creating root and stump suckers that can quickly come back. When the trunk is taken care of, the remaining roots will begin to decay and won’t be able to grow back. Stump grinding is one way to make sure poplar trees don’t reincarnate and grow back. 

Another way to make sure poplar trees don’t grow more suckers is to cover the stump in Epsoak Epsom Salt. Epsom or rock salt is a cost-effective, albeit very slow way to prevent any growing back.

When you’re not concerned about how long it will take for the stump to decay, you can use this method to finish off the tree after it is cut down. Depending on conditions, the stump could take 3 to 5 years for it to decompose. 

Once the tree is cut down and removed you can pour a layer of Epsom salt over the flat surface of the stump then cover it with Frost King Polyethylene Sheeting to keep the rain from washing it away. 

To accelerate the process, drill holes into the stump, and around the perimeter with a ½” drill bit or auger bit, then fill the holes with salt.

Next, add water to the salt-filled holes to help spread it throughout the stump. Cover it with plastic and check on it every few weeks. Add more salt and water if the tree looks like it’s still trying to hang on. 

The Epsom salt dries out the wood and prevents water intake from the roots. When it’s no longer living, it will start to decay. Now you no longer have to worry about new poplar trees coming from that stump.

If you’d like another option, take a look at our guide on using vinegar to get rid of tree roots as well!

Stop Poplar Seedlings Once You Spot Them

As we have seen, even poplar seedlings can quickly grow to maturity and start growing more clusters of trees, so any seedlings have to be eradicated or you’ll be right back where you started in a few years.

Seedlings and saplings need to be removed at the root or they will end up growing back too. For smaller seedlings, it might be easier to remove them after a good, soaking rain. This way the soil is soft and loose and you should be able to remove all the roots along with the trunk.

For small saplings that are too big to pull out by hand, you’ll have to dig them out. Digging the roots out as wide as the canopy is, should be enough to keep the tree from coming back.

After you have removed the poplar trees you might be feeling like you need to replace them with another tree.

Of course, if you’re feeling hesitant after dealing with that invasive headache, we understand, and we got you covered. Check out our article on what shade trees don’t cause root problems to find the proper alternative!

Wrapping Up!

Poplar trees, despite being a very invasive species, definitely have some great uses. They are great for lumber, especially plywoods and OSB boards because they grow so quickly and are easily regrown.

They can be effective windbreakers as well, but they are not suited for home landscaping projects.

Unfortunately, because poplar trees grow so fast and are incredibly plentiful they are planted in American landscapes all the time.

If you have poplar trees on your property, you might need to have them removed to keep them from spreading everywhere and taking over.

Best of luck on your poplar tree journey!

References

Hamelin, Caroline, Benoit Truax, and Daniel Gagnon. “Invasive glossy buckthorn impedes growth of red oak and sugar maple under-planted in a mature hybrid poplar plantation.” New Forests 47.6 (2016): 897-911.

Thomas, Lisa K., and Ilona Leyer. “Age structure, growth performance and composition of native and invasive Salicaceae in Patagonia.” Plant Ecology 215.9 (2014): 1047-1056.

Riemenschneider, Don E. “Breeding and nursery propagation of cottonwood and hybrid poplars for use in intensively cultured plantations.” 

Landis TD, Thompson JR, technical coordinators. National proceedings, forest and conservation nursery associations. Portland (OR): USDA Forest Service, Pacific Northwest Research Station. General Technical Report PNWGTR-419. p (1997): 38-42.

Stanton, Brian, et al. “Hybrid poplar in the Pacific Northwest: the effects of market-driven management.” Journal of Forestry 100.4 (2002)