You’re likely no stranger to seeing root-bound plants and trees, and, frankly, that can have a long-lasting impact on your tree's health. In contrast, air pruning is changing the way trees are grown. Whether you're a homeowner, HOA manager, or urban forester, understanding how air pruning works—and why root health matters—can help you make smarter choices for long-lasting, beautiful trees.
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Growing region, climate, and soil all impact which species are best suited for a specific area. While all of those elements are variable depending on where you live, one factor all trees have in common is the need for deep and extensive roots– to establish, grow, and thrive.
Because newly planted nursery trees often start with only 5–20% of the root system they would have in open ground, rapid root development is essential. Research shows that not only do air-pruned container-grown trees develop significantly more root tips and total root length, but they also produce more shoots and leaves when compared to conventionally grown nursery stock.
It’s not just about tree growth, though. Tree resilience is another crucial factor, and root health plays a significant role in ensuring strong trees capable of withstanding weather events. For urban soils that are frequently compacted or saturated (especially near pavement), tree roots are often shallow and stressed. For example, in 2024, winter storms in Portland uprooted nearly 600 trees; experts noted that compacted, waterlogged soils and drought-shrunken roots made city trees prone to falling. Healthy deep roots could have worked to lessen the impact.
Healthy root systems do more than boost canopy development and resilience to stress. If roots are damaged or insufficient, trees struggle to access water and become more vulnerable to drought. For example, Utah arborists found that abruptly cutting irrigation (such as after lawn or turf removal) can cause existing root systems to dry up. In turn, this inhibits new growth and can also lead to crown dieback within a few years.
Finally, trees with compromised roots are incredibly vulnerable to wind. One Colorado study confirmed that trees with “structurally weakened root systems” can fall over during wind storms, meaning it’s not just a case of soil quality.
Further, studies reveal that strong root systems can also help trees survive droughts. For example, research showed that conifers could survive a five-year drought only when they entered it with deep, water-seeking roots already in place. Unfortunately, trees forced to grow new roots during the drought all perished.
Maintaining healthy, well-aerated roots is crucial for swift establishment, vigorous canopy growth, and long-term vitality of urban trees in these western regions.
Wondering what trees to plant? Get our Tree Selection Checklist here!
We’ve mentioned air pruning a few times, particularly regarding healthier root systems, so it’s essential to understand what it is and how it’s different from traditional container-grown nursery stock.
If you’ve ever done planting at home and removed the pot to transfer your plant, you’ve likely seen a root system that circles the soil, often taking the shape of the pot itself. In this case, the plant's roots have outgrown the container and, with nowhere else to go, they circle the inside of the pot, becoming tangled, dense, and compacted.
Unfortunately, root-bound trees are common in traditional nursery containers, so methods like air pruning are preferred.
Air pruning encourages healthy, fibrous root development by exposing the tips of growing roots to air. When roots reach the edges of specially designed containers or beds, made with open sides or breathable fabric, the exposure to air naturally dehydrates the root tip. This signals the plant to branch and produce more lateral roots instead of circling or becoming root-bound.
This result is a dense, well-structured root system better equipped for nutrient absorption, drought resistance, and long-term stability once planted. Air pruning is especially valuable for nursery-grown trees, ensuring healthier transplants and faster landscape establishment.
Traditional root development, especially root-bound trees, can lead to serious long-term issues for trees. Once planted, these circling roots can grow in unnatural patterns, leading to poor anchorage, restricted nutrient uptake, and even girdling, where roots strangle the trunk over time. Similarly, trees grown in compacted or saturated soils may develop shallow, weak root systems, making them more vulnerable to drought, disease, and windthrow.
Air pruning transforms tree roots' development by naturally guiding them into a dense, fibrous network rather than allowing them to spiral or clump. As noted above, when root tips encounter air at the edge of their containers or growing beds, they dry out and stop growing in that direction. The tree then produces new roots further back in the system. Much like a stronger core in a person that promotes strength and stability, the same is true for an air-pruned tree. Their root system is stronger and more efficient, promoting faster establishment and better performance.
If you’re looking for trees that will thrive long after planting, sourcing from a tree nursery that uses air pruning is a smart place to start. But, because not all nurseries advertise their growing methods openly, knowing what to ask is essential.
Wondering what to ask? We’ve got you covered.
Simply asking the questions is excellent for helping you purchase a tree with healthy roots, and it’s always best to go into any investment as an informed consumer. Still, it may be easier to start with a nursery using the air pruning technique.
Wondering where to look? We can help.
Trees are an investment, and, as with any growing thing, giving them a good, strong start is key. That means starting with a healthy root system so the tree establishes quickly, grows strong, and remains weather and storm-resilient.
SuperTrees has been using air pruning technology for decades, and we welcome you to visit one of our retail nurseries to see for yourself. We’re here to help you get the most out of your trees and to ensure their successful establishment and ongoing health. We know that starts with strong, healthy root systems.
Whether you’re planting for your home, community, or city, we have the stock to support your goals and the team to support your investment along the way. Give us a call and let’s get planting!