Gardening Plants & Flowers Trees

Quaking Aspen Tree: Care & Growing Guide

Fast-Growing Trees With Unique Heart-Shaped Leaves

Quaking aspen trees with yellow, orange and green leaves in mountainside

The Spruce / Meg MacDonald

The quaking aspen (Populus tremuloides), a name that refers to how its leaves tremble at the slightest breeze, is a tree in the willow family. Other common names refer to such features as its fall color (golden aspen), bark color (white aspen), or favorite habitat (mountain aspen).

It's easily identified by its smooth, light-colored bark, interrupted at intervals by darker knots and horizontal scars. An even better-identifying feature is its flattened leafstalks, which cause the leaves to "quake" when the wind blows. The leaves are rounded to slightly triangular, 3 inches across, and finely toothed. The flower or seedhead is a catkin.

Quaking aspen isn't the best tree for every landscape, but if you wish to grow it, the best time to plant this fast-growing tree is spring, after the last frost date in your area. It grows about 2 feet a year. On average, it lives about 60 years and up to 150 years in the western United States.

Fun Facts

  • Quaking aspens can sprout new trees from one root underground. So, even if a tree dies after 60 years or so, a new shoot from the same root underground may produce another clone. So, the root may live underground for tens of thousands of years.
  • Pando, a grove of quaking aspens in Utah, is surmised to be the oldest living organism on the planet. Some researchers suggest it's a million years old, while others are more conservative, suggesting it's a little younger than the last ice age, 12,000 years ago.
Common Names Quaking aspen, trembling aspen, American aspen, golden aspen, mountain aspen, trembling poplar, white poplar
Botanical Name Populus tremuloides
Family Salicaceae
Plant Type Tree
Mature Size 20-50 ft tall, 20-30 ft. wide
Sun Exposure Full
Soil Type Well-drained
Soil pH Acidic, neutral, alkaline
Hardiness Zones 1-6 (USDA)
Native Area North America

     

Quaking Aspen Tree Care

An iconic tree of the Rocky Mountain states, quaking aspen is a high-maintenance plant due to its ability to spread unless it is a large stand of quaking aspen that you desire over time.

Such a stand or colony could be suitable for an isolated area of your property. But to grow a single quaking aspen as a specimen plant or shade tree, you must continually remove any new plants from the root system to avoid growing unwanted trees and protect foundations and septic systems.

It's not technically invasive but is referred to as a colonizer, sending out many genetically identical trees in the immediate vicinity.

Quaking aspen tree with small golden-yellow leaves closeup

The Spruce / Meg MacDonald

Quaking aspen tree with white tree bark in front of aspen trees with yellow leaves

The Spruce / Meg MacDonald

Quaking aspen trees with golden-yellow and green leaves in front of mountainside

The Spruce / Meg MacDonald

Light

Grow quaking aspen tree in full sun for best results, although it does tolerate some shade.

Soil

Provide quaking aspen with good drainage. An average garden loam is sufficient.

Water

For best results, keep its soil evenly moist.

Temperature and Humidity

Quaking aspen does not handle heat and humidity well. It is not suited to regions such as the American Southeast.

Fertilizer

Quaking aspen performs best in moderately rich soil. Fertilize it with a complete fertilizer in early spring for an extra boost. Follow the instructions on the fertilizer package precisely. The instructions will spell out how much fertilizer to use, which varies according to tree size. Over-fertilizing can burn your plant.

Types of Aspen (Poplar) Trees

There are several trees in the Populus genus. They are commonly referred to as "poplars," sometimes as "aspens." Examples include:

  • Japanese poplar (Populus maximowiczii): A columnar tree with the virtue that it does not produce suckers, thereby reducing maintenance
  • Lombardy poplar (Populus nigra): A columnar tree often planted along property borders, but it does produce suckers
  • White poplar (Populus alba): Although Populus tremuloides is sometimes called "white poplar," Populus alba is a distinct species. It is valued for its silvery leaves, but its downside is that it's invasive.

Pruning

The best time to prune quaking aspen is winter because this is when the tree is dormant, meaning the tree will tolerate cuts better. Quaking aspen must be pruned after heavy winter snowfalls have damaged limbs. The damaged limbs should be pruned back to the collar. Dead or diseased branches should be pruned off whenever you spot them.

The only need for discretionary pruning is generally when growing the tree in an area where you will be walking regularly. You may wish to remove low-lying limbs there (rather than having to duck under them when walking). Again, prune such branches back to the collar.

Propagating Quaking Aspen Trees

Quaking aspen spreads naturally through its root system, developing into large stands over time. In such a stand, one tree is a clone of the next. The trees are also dioecious, with distinct male and female colonies. Because quaking aspen trees propagate readily through their root systems, you can take advantage of this fact to acquire new trees.

Simply dig up offshoots from the original tree and transplant them to a suitable location in your landscape. This is by far the easiest way to propagate quaking aspen.

How to Grow Quaking Aspen Tree From Seed

You can also grow it from seed, but it's more troublesome. If you go this route, at least simplify matters by buying the seed rather than trying to harvest it from the wild. The latter is difficult for beginners because the pollinating male plants don't look much different from the seed-bearing female ones (both produce catkins).

Once your seeds arrive, fill a planting container with moistened seed-starting medium. Sow the seeds right on top of the seed-starting medium; don't cover them with soil. Keep the medium moist; placing the container in a plastic bag will help trap moisture. Seeds will germinate in 24 hours. Place the container in a window for light. Plant outdoors after all danger of frost has passed.

Overwintering

Quaking aspen is cold-hardy all the way to zone 1, so no extra care is required to overwinter it.

Common Pests & Plant Diseases

Quaking aspen is susceptible to infestations of poplar borers. The larvae do the boring, and their holes invite damaging fungi into the tree. But these beetles typically attack trees that are in poor health. Thus the best control measure is to keep your tree in good health by ensuring its light levels, irrigation, and drainage, are adequate.

Quaking aspen can be attacked by powdery mildew disease. Quaking aspen likes evenly moist soil, but you must strike the right balance between dry and soggy soil. Soggy soil invites fungal infections. Likewise, don't get the leaves wet when watering. Also, water early in the day so that excess water evaporates before nightfall. Practicing good garden hygiene can also help prevent this fungal disease. Remove and dispose of any diseased leaves or branches.

Common Problems With Quaking Aspen Tree

Quaking aspen is prone to attacks from browsing animals, insects, and diseases. It's also susceptible to environmental factors.

Browsing Animals

One of the biggest problems quaking aspens face is they are a favorite food source for deer and elk. The animals seriously damage aspen trees by eating the shoots of young suckering trees that sprout from the aspen’s root system and by eating bark. Deer and elk also rub their antlers against the bark causing deep gashes that can kill the tree. The most significant damage occurs during mating season (September to November).

To reduce tree damage, use strong barrier fencing to keep animals out. You can also wrap bark in rigid plastic, reducing damage, although a large elk can still damage or destroy a wrapped tree. Remove all wraps in the spring.

Bark Discolored or Falling Off

Sunscald can cause a quaking aspen's bark to become discolored, crack, fall off, or sink into the trunk. This condition occurs during winters with freezing weather dotted with unseasonably warm days. The warmth might confuse the tree, thinking it should come out of dormancy and prepare for spring growth. However, when the cold returns in full force in a few days, the tree isn't dormant and prepared to handle the cold properly.

If your area experiences winters with frequent unseasonable warm snaps, consider painting the trunk with white latex paint to deflect sun rays. Also, make sure your aspens are receiving ample water. Drought-stressed trees are more likely to suffer from sunscald. If your tree has already been damaged from sunscald, do not paint the damaged bark sections. Allow it to heal.

Browning of Leaves

Browning leaves can be a sign of aspen leaf scorch, caused by aspens not getting enough water during hot and dry periods. There's no quick fix or cure. Maintaining a watering schedule is the best way to bring your tree back to health. During the growing season, these trees need infrequent but deep watering. In the winter, ensure these trees get a deep soaking at least once a month (if no snow is on the ground).

Leaves Turning Pale Yellow or Light Green in Summer

Your soil might have an iron deficiency if green leaves start turning pale green or yellow unseasonably soon, like in summer. This condition is called chlorosis. You might notice the yellowing beginning at the edge of the leaves and then moving to the center. The leaf edges may turn brown, start curling, or fall off. If it's an iron deficiency, the tree could benefit from chelated iron deep root injections into the soil around the tree. In extreme cases, injections into the tree might be needed.

FAQ
  • Does quaking aspen have aggressive roots?

    You can't grow quaking aspen around water lines or septic tanks. This guidance holds for all trees and shrubs in the willow family, including the ever-popular pussy willow (Salix discolor).

  • Does quaking aspen tree have nice fall foliage?

    Quaking aspens have a brilliant golden-yellow color in fall.

  • Are quaking aspens messy?

    Quaking aspens are among the prettiest trees but are also messy in terms of their maintenance. You must continuously remove the suckers or new shoots from their spreading root system.

  • Do aspen trees need a lot of water?

    Quaking aspens should get water regularly. Every two to four weeks, they should get a deep watering. During hot summers, they should have water at least every other week. In winter, the trees need water at least once a month if snow isn't already on the ground.

  • Is the quaking aspen tree good for a yard?

    Quaking aspens are beautiful, fast-growing trees, but many experts do not recommend aspens for a yard because of their suckering growth habit. This tree prefers to clone itself into stands or groves. This tree is only suitable for a yard if you want a stand of trees or don't mind continuously removing the suckers or shoots that its root system will develop.

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  1. Quaking aspen. National Wildlife Federation.

  2. The biggest living thing on Earth is being nibbled to death. Can it be saved? National Geographic.