Quaking Aspen trees (Populus tremuloides) are very popular trees for a number of reasons. They are drought tolerant once established, are very hardy in nature, are native to Colorado, and are striking in appearance with their fluttering green leaves and stark white bark. Aspen trees are prized for their quick growth, growing nearly two feet per year until they reach mature size. Aspens can grow up to 70 feet tall in nature, but in residential environments, they are more likely to reach 50-60 feet tall with a spread of approximately 20-30 feet. While it is more natural for them to grow at higher elevations where the soil is sandy, loose, cool, and moist, accommodations can be made to help aspen trees thrive in yards across Northern Colorado and the Front Range.
When Can You Plant Aspen Trees in Colorado?
As with all trees, the ideal planting season is in early spring. Planting in early spring gives your new tree the most time to establish a strong and healthy root system which will ensure that it is capable of withstanding the harsh, cold winter. If you missed planting this spring season, trees can also be planted in the summer or fall. With summer planting, you will just need to be aware of the extreme temperatures. Newly planted trees need significantly more water in their first 1-2 years of growth after planting as this is when they are working the hardest to establish themselves. Without adequate water, your tree will not be able to establish itself, and this will not set your tree up for success in the future. If you choose to plant in the summer, just be aware of the fact that you will likely need to water your tree at least two times per week, if not more often during extremely hot spells. Fall is also a good season for planting. The summer temperatures have begun to calm down, and this takes much stress off of your tree. Still be aware that you will need to water it deeply and frequently! Since fall planting does not allow an entire season of root growth, you will want to also be diligent with watering your new aspen tree throughout the winter season if there is ever no snow covering the ground. This will help make sure the roots of your tree do not dry out past the point of being able to recover come spring.
So, just to recap, you can plant aspen trees in Colorado in the spring, summer, and fall, just be aware of the different needs of your tree based on the season and be sure to attend to it carefully in order to ensure its strong and healthy development!
How To Plant Colorado Aspen Trees
Here is a quick guide on how to plant Colorado aspen trees to ensure that your tree will grow strong, healthy, and beautiful!
1. Select Your Tree
It is generally best to pick a tree out of the selection offered at your local Garden Center & Nursery. Aspen trees do tend to be susceptible to a variety of pests and diseases, and attempting to grow a wild aspen tree in your yard can bring a plethora of problems along with it, since at one point or another it may have already been exposed to some sort of ailment. With nursery-grown aspen trees, great care and attention are put into making sure they are pest and disease-free. This does not mean that your tree is impervious to such things, it only means that your tree is much less likely to be stricken with issues throughout its life.
2. Select the Right Space
Aspen trees prefer to be planted in full sun and can tolerate partial shade, however, it may be best to avoid planting them in an area that gets extremely hot or receives a lot of intense, direct sun throughout the summer (such as the south-facing side of your house). While Colorado aspen trees like a lot of sunlight, they do not handle intense heat well and prefer to grow in well-draining soil that is cool and moist. Such conditions can be difficult to maintain in areas of your yard that receive the most sun.
3. Prepare Your Space
Once you have selected the perfect space for your aspen tree, it is time to prepare the soil. Aspen trees do not grow well in the dense, clay-heavy soil that is so common. If this is what your soil is like, you will want to replace a lot of the soil around where you are planting your tree with high-quality topsoil. You will also want to mix some sand into the soil to help improve drainage and add some compost to help enrich the soil and give the newly planted tree extra nutrients. Most of all, your tree will require light and fluffy soil that has good drainage. For even more details on how to prepare a space for your new tree or shrub, check out our tree and shrub planting guide!
4. Plant Your Tree
Once you have amended your soil to suit the needs of your aspen tree, it's time to put it in the ground! Place it in the hole you have prepared and take a step back to ensure that the tree is upright and not tilted to one side or another. Take a look at the tree from all angles! Once you have the tree positioned to your liking, gently and evenly fill in around the base of the tree with your amended soil mixture, being careful not to knock it out of place. Gently tamp down the soil around the base of the tree until it feels secure. Aspen trees do not like soil that is overly compact, so be careful not to be too forceful when packing down the soil.
5. Maintain Your Tree
Right after planting, there are several things you should do to make sure it gets off to a good start. First of all, you will want to give it a good watering. Be sure to water slowly and for an extended amount of time, versus a gush of water for a short period of time. This will ensure the water soaks deep around the base of the tree and will encourage deep, strong roots. Second, adding tree straps and staking your tree will help ensure that it does not get blown or knocked over. This can actually happen much easier than you might think in the tree's first year of growth as its roots have not yet had a chance to dig into the surrounding soil. A little extra stability is very helpful for a newly planted tree. Lastly, adding a layer of mulch around the base of your aspen tree will help the soil maintain moisture, which your tree will appreciate! If you use pine bark, this will naturally break down into the soil, helping to acidify the soil, which will also be a plus for your new tree!
Aspen Tree Growing Tips
1. Water Consistently Throughout the First Year of Growth
Remember, consistent watering throughout the first year of the tree's growth is imperative for healthy and strong root development!
2. Ensure the Soil Drains Well
Your aspen tree may experience stunted growth or may drop its leaves before they change colors for the season if the tree is not planted in soil that suits it. So, if you want a healthy tree or if you really want to be able to experience its brilliant fall color, be sure to plant your tree in the correct soil!
3. Do Not Plant Near Water Pipes or Your Home's Foundation
Aspen trees grow as a part of a network and have rather aggressive root systems. For this reason, it is not recommended to plant an aspen tree near any water pipes, building foundations, or any other underground structures that could sustain significant damage from the fast-growing roots! They should also be planted approximately 10 feet away from other trees.
4. Aspen Trees Grow Very Quickly and Reproduce Aggressively
With their aggressive root systems also comes aggressive reproduction! Once your tree is mature, you may begin to notice it starting to send up shoots in the surrounding area. These little shoots are attached to the main tree via the root system and will grow to be full-sized, mature trees if allowed. You can cut these back with pruners or mow them down, but it is not recommended to use chemicals to thwart their growth as this could damage the rest of the trees in the area.
5. Be Aware of Pests and Diseases
Colorado aspen trees can be more susceptible to pests and diseases when grown outside of the high-elevation, mountainous regions they prefer. So, just keep an eye on your tree, and if you begin to notice any bugs, discolorations, or similar things that seem out of the ordinary, contact an arborist right away to get their professional opinion on how to treat your tree before the situation becomes worse.
Growing Aspen Trees in Colorado
If you have any further questions about how to plant and grow your aspen tree Colorado, feel free to reference our Tree & Shrub Planting Guide or give us a call! Our Nursery department puts a lot of effort into making sure that we carry the healthiest trees that are most likely to grow and thrive in your yard. We also have a large variety of trees on the property throughout the entire growing season, so feel free to stop by and check out our selection of trees and shrubs for Colorado planting!