Pruning is the most common tree care service — and one of the most commonly done wrong. Improper pruning doesn't just look bad; it creates wounds that trees can't close properly, opens the door to decay and disease, and can structurally compromise trees for decades. Done right, pruning improves structure, reduces risk, and extends tree life.
The Biology Behind a Good Pruning Cut
Trees can't heal wounds the way animals do — they can't regenerate tissue. Instead, they compartmentalize: they wall off the wound chemically and structurally, preventing decay from spreading. The speed and effectiveness of this compartmentalization depends almost entirely on where and how the cut is made.
The branch collar is a slightly raised area of tissue at the base of every branch where it meets the trunk or larger limb. This collar contains the trunk tissue and the beginning of the branch tissue, and it is genetically programmed to seal over wounds. A proper pruning cut preserves the branch collar — just outside it — so the tree can close the wound effectively.
What Bad Pruning Looks Like
- Flush cuts — cutting directly into the trunk, removing the branch collar and creating a wound the tree cannot properly close
- Stub cuts — leaving excessive stub beyond the branch collar, which dies back and creates an entry point for decay
- Lion's tailing — stripping interior foliage and leaving only a tuft at branch ends, which weakens branch attachment and invites sunscald
- Topping — cutting branches to stubs at arbitrary heights, which destroys tree structure and leads to vigorous but weakly attached regrowth
Topping is one of the most destructive practices applied to trees. If someone recommends topping your tree, that is a red flag. The resulting waterspouts are weakly attached, prone to failure, and the practice ultimately shortens the tree's life rather than making it safer.
ANSI A300 Standards: The Industry Benchmark
The American National Standards Institute (ANSI) A300 standards are the accepted industry guidelines for tree pruning in the United States. They define the acceptable types of pruning cuts, limits on how much foliage should be removed at one time (generally no more than 25%), and the objectives for different pruning types.
ISA-certified arborists are trained to these standards. When Emerald Tree Care prunes a tree, we're applying these principles to every cut — not just making the tree look a certain way, but making cuts that support the tree's long-term health and structural integrity.
Types of Pruning and When Each Is Appropriate
Crown Cleaning
Removes dead, dying, diseased, weakly attached, or crossing/rubbing branches. This is the most common type and is appropriate for most trees on a regular maintenance schedule.
Crown Thinning
Selectively removes branches to increase light penetration and air movement through the crown. Used to reduce weight on heavy limbs, improve interior branch health, and in some cases reduce wind resistance.
Crown Raising
Removes lower branches to provide clearance for pedestrians, vehicles, buildings, or sight lines. Should be done gradually over several years to avoid removing too much of the live crown at once.
Crown Reduction
Reduces the overall size of the crown by cutting branches back to laterals. This is different from topping — proper reduction cuts are made at branch unions where a lateral of adequate size can assume the terminal role.
Timing Matters for Some Species
Most pruning can be done year-round, but timing matters for some species. Oaks should not be pruned during the growing season (April through July) in Illinois because fresh wounds during that period attract the beetle vectors that spread oak wilt. Elms are also best pruned in winter to reduce Dutch elm disease risk. When in doubt, a certified arborist can advise on the best timing for your specific trees.
If it's been more than 3-5 years since your trees were professionally pruned, or if you're seeing dead branches, crossing limbs, or structural concerns, contact us for a pruning consultation.
