Cutting Roots to Promote Healthy Growth for Potted Trees

Jeana Cadby
October 29, 2020

Landscaping with container-grown trees is a wonderful way to access a diversity of tree species and sizes, while widening the window for tree planting and dig times. When transplanting potted trees, using best practices is critical and will often determine the long-term health and longevity of the trees.

Cutting tree roots is one of the most important steps in the planting process for potted trees. Read on to find out more about cutting roots to promote healthy growth for potted trees.

Find Your Roots

Proper cutting of tree roots can help prevent the development of girdling roots in landscaping trees. Girdling roots restrict water and nutrients as horizontal roots encircle the base of the tree, weakening the tree over time.

Container grown trees may develop circling roots, especially when left in pots for too long or when undersized pots are used. When left untreated, circling roots will develop into girdling roots and cause long term tree damage, dieback, and eventually tree death. Although some species of trees are more susceptible to forming circling roots, any tree can be at risk. Pot or root bound trees are formed when horizontal circling roots grow against the inside of the pot, encircling the root ball. Roots will continue to grow in a circling pattern if left untreated and supporting roots will struggle to grow, leading to unstable mature trees in the landscape.

Trees are also susceptible to transplant shock, which occurs when the trees do not have an established root system that can keep up with the needs of the plant. Symptoms of transplant shock include leaf scorching and discoloration, reduced plant growth and vigor, and wilting or curling leaves, and can be exacerbated with stress arising from circling and girdling roots.

Making the Cut

Cutting roots before transplanting can also help promote healthier growth for potted trees and encourage new root growth. Root pruning and removal can be stressful for the tree but is ultimately better for the long them health of the tree, especially when compared to the stress and weakening from girdling roots.

Before cutting, examine the root ball carefully and remove any synthetic materials. Then, prune any broken or damaged roots, especially roots that appear to be circling around the top of the root ball. Some landscapers will also make several vertical cuts down the sides of the root ball to enhance the distribution of new root development.

Some mature roots may not be malleable enough to reposition out of their spiral formation. Prune woody roots that are no longer malleable back to a lateral root. Then, carefully loosen and tease malleable circling roots from the root ball and spread out evenly. During this process, it is also important to expose the root flare, or the point where the tree roots ‘flare’ out from the trunk of the tree by carefully removing soil at the base of the trunk.

Tips for Success

Improper tree planting can significantly influence the chances of transplanting failure, and planting trees at the right depth can help prevent girdling roots from forming. The top of the root ball should be level with the ground or 1-2” above soil level. Plant trees as soon as possible after delivery and ensure that transplantation occurs at the proper time for the tree being planted.

A consistent and calculated watering and fertilizer regimen, tailored to the needs of the tree, can help to maintain plant health after transplanting. Too often, trees without the adequate root systems to take up large volumes of water are over watered, leading to root rot and tree death.

Conclusion

Proper cutting of the roots of potted trees can help promote healthier growth after transplanting. Root girdling is a serious problem that can arise if circling roots are not addressed, leading to restricted water and nutrient flow and weakened plants. Proper planting techniques include cutting roots before planting and planting trees at the right depth.

Do you have a favorite long-lived, healthy tree? Check out our website for more tips on how to plant a tree and other discussions on how to promote tree health.

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