Water sprouts, suckers, and root shoots—different names for the same phenomenon. Epicormic growth is the botanical term for shoots that arise on the main trunk or branches. Unlike normal twigs, which grow from branch tips and follow the tree’s structure, epicormic shoots develop rapidly—often within a month or two—growing straight up in clusters, loosely attached and randomly distributed throughout the crown. Proper pruning plays a key role in managing these growths and maintaining a tree’s overall health and appearance.
While these growths may appear messy and disrupt the tree’s aesthetics, they are actually a sign that the root system is active and the tree is naturally responding to stress. In other words, as an arborist, I view epicormic growth as a positive indicator of a tree’s health.
Considerations Before Pruning
Many customers and even arborists will aggressively elect to remove sucker growth when it occurs. However, one should exercise caution and consider why the tree is producing so many suckers. When you think about it, sucker growth is a strong reaction to something occurring in the tree. Homeowners may be right to think that they shouldn’t be there, but they should not just remove them without investigating why they appeared in the first place. You could be entering an aggressive cycle of removal only to have them regrow in the same number, if not more. Eventually, the tree will start to decline, as producing suckers takes a lot of energy.
Reasons Sucker Growth Can Occur
- Environmental Stress
- Over-Pruning Reaction
- Insect Attack Response (e.g., aggressive sucker growth may indicate emerald ash borer infestation)
- Grafting Union on Ornamentals
- Vascular Disruption
- General Decline
Physiologically, trees must have sufficient leaf area in order to sustain themselves. The root system and the canopy grow in proportion to one another, meaning if a substantial amount of leaf area is removed, the root zone remains and will work hard to reestablish the lost canopy. After all, growing roots is very energy-consuming, and the roots are necessary not just to support the canopy but also to provide anchorage and stability to the entire tree. The tree really does not want to give up the root zone.
Certain pruning practices can increase sucker growth, such as aggressive pruning (typically more than 25% in one event). Aggressive thinning along the main stem can cause sucker growth because the tree needs sufficient tissue along the stem to help move water from the ground upward.
Best Practices for Controlling Sucker Growth
If you are looking to control sucker growth, you should first consult with a certified arborist to make sure that there are no other issues occurring with the tree. No more than one third of the current suckers should be removed at a time to avoid rapid regrowth. Do not apply an herbicide to suckers or root shoots occurring at the ground. This is a common mistake that can poison the entire tree, causing severe disfigurement and possible death.
Lion’s Tailing: A Controversial Pruning Technique
This is a nickname for a pruning technique where all the stems along the main stem are removed and only a few twigs are left. The visual effect is that of a lion’s tail with just a poof of hair (branches) at the very end. This pruning technique is not deemed acceptable by the International Society of Arboriculture. You typically see this type of pruning done by professionals who are not certified arborists and by homeowners who do not know any better. The goal is typically to increase visibility through the tree, encourage turf growth (which you need to treat), or decrease leaf area—especially for those who don’t like picking up weeds in the fall. Sometimes, people prune this way because they believe it will reduce the likelihood of stem or whole tree failure.
Unfortunately, the opposite is true. At the root flare, the trunk actively thickens to resist stress and wind-loading—making it the tree’s strongest part—while overlapping wood tissue reinforces the branch collar as the next strongest area. When a branch loses more than 30% of its leaf tissue, the stress shifts from the branch collar to the weaker mid-section, making it more likely to break. Similarly, a lion’s tail shape leaves the tree most vulnerable just above the branch collar.
Enhance Tree Health Through Thoughtful Pruning & Expert Guidance
Before taking any action on sucker growth, Petrarca Landcare advises that you first investigate why the tree is producing these shoots. A thoughtful, measured approach not only preserves the tree’s aesthetic appeal but also its overall health and structural integrity. For expert guidance, always consult with a certified arborist.
