By: Joel Potter, Urban Regional Extension Agent, Certified Arborist SO-5743A |www.MobileCountyMasterGardeners.org
Fall is the ideal time to plant trees on the Gulf Coast due to the region's mild temperatures and consistent rainfall, which create perfect conditions for root establishment before the heat of summer. However, citrus trees are a notable exception and should be planted in the spring to prevent frost damage. Planting a tree is an investment in the future, but for that investment to thrive, proper preparation of the tree’s root ball is crucial. The root ball—the mass of roots and soil that accompanies a transplanted tree—plays a significant role in determining the tree’s success in its new environment.
The first step is to ensure that you start with a good root ball, which requires careful inspection at the nursery. It's important to locate the trunk/root flare or the first structural roots, which should be near the soil surface; sometimes, you may need to gently pull back soil to find them. The root flare is the area at the base of a tree where the trunk widens and transitions into the roots, and it should be at or near the surface. Trees with their first substantial roots buried too deep in the pot will have a smaller volume of roots and should be avoided if possible.
Typically, you can slip the root ball out of the container to inspect it, but it is important to ask for permission from the nursery first. Trees with excessive circling roots should also be avoided, and particular care should be taken to look for roots that wrap back across the trunk, known as girdling roots. Additionally, the root ball should not be dark brown, black, or have a foul smell, as these are signs of poor health.
When planting, the pot should be removed to inspect the root ball and plan how to prepare it for planting. It's crucial to keep the root ball moist throughout this process, as even brief drying out can severely impact the tree. The goal is to encourage the roots to grow outward and away from the base of the tree, eliminating crossing and circling roots where possible. A simple method is to remove vertical slices along the root ball all the way around, as shown in the photo. A slice can also be removed from the bottom of the root ball if circling roots are observed there. This promotes outward root growth by addressing the circling roots. The root ball should then be gently teased out to identify any hidden circling roots and to encourage them to grow outward during planting.
In cases where substantial circling roots are observed within the root ball, more drastic measures may be necessary. It can be beneficial to wash the root ball, removing all potting media to fully observe the root system. Pruning shears can then be used to eliminate circling and girdling roots, helping to achieve a more desirable root structure.
A five-gallon bucket or wheelbarrow filled with water can be used to soak the root ball and remove the media. This method is more stressful to the tree and may increase the need for post-planting care, but it can prevent fatal defects later in the tree's life. Smaller, vigorous trees are generally more resilient and can withstand more aggressive root pruning than larger trees.
The roots are the most important part of a tree, and this is likely your only opportunity to directly manipulate them. Take your time and be deliberate with your actions. Good root ball preparation, a wide and shallow planting hole, and a little TLC will set up your tree to thrive for generations to come.
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