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| Welcome to our tree column, “Ask your local arborist.” Each month, arborist George Reno from the Davey Tree Expert Company in Menlo Park discusses a tree-related topic from general care and planting tips to how trees can impact your property. If you have a tree-related question or an idea for a topic to discuss, email lifestyle@embarcaderopublishing.com or post in the comments section at the end of this colum |
Early summer often sparks the annual debate over when to prune. While tree trimming is commonly associated with winter dormancy, this season can also be an important window for thinning and shaping certain trees, depending on the species, their health and your goals.
Some trees respond well to selective cuts in early summer, while others are best left untouched until they go dormant. Knowing the right timing and approach is critical.
Cutting the wrong tree at the wrong time can cause stress, reduce flowering and leave it more vulnerable to pests and disease. Winter remains the preferred season for major structural work, but some species benefit from light trimming in late spring or early summer after new growth has emerged. It’s also one of the easiest times for homeowners to identify problem limbs, as fully leafed-out canopies make defects easier to spot.
Early summer trimming can help:
- Remove dead, damaged or storm-weakened limbs
- Improve airflow and reduce dense canopy growth
- Manage vigorous spring growth
- Address safety concerns before summer heat stress
Not every tree should be pruned now
One of the biggest misconceptions is that all trees should be pruned the same way and at the same time. In reality, the best timing depends heavily on species and bloom cycles. Over-pruning during hot summer weather can expose bark and interior branches to sunscald or drought stress, especially during heat waves.
General seasonal pruning guidelines include:
- Spring-flowering trees such as cherry, redbud and magnolia should generally be pruned shortly after flowering finishes.
- Oaks should be pruned carefully and strategically during the dormant winter season. Avoid pruning them in spring or summer.
- Maples and birches are often pruned in late spring or early summer after leaf-out to reduce excessive sap bleeding.
- Deadwood and hazardous limbs can typically be removed at any time of year.
Why improper pruning causes problems
Poor pruning practices can create long-term structural issues and unnecessary stress for trees. Topping trees, removing too much live canopy at once or making improper cuts can weaken branch attachments and encourage weak regrowth. Trees rely on their canopy to produce energy, regulate temperature and protect bark from sun exposure, especially during summer.
Common pruning mistakes include:
- Removing more than 25% of the canopy in a single season
- Leaving stubs instead of making clean cuts
- Topping trees to reduce height
- Pruning during extreme heat or drought conditions
How to approach pruning this season
For homeowners considering tree work this time of year, a lighter, more intentional approach is often best.
A few smart summer pruning tips include:
- Focus on dead, damaged or crossing branches first
- Avoid heavy canopy reduction during heat waves
- Use clean, sharp pruning tools to prevent disease spread
- Check for bird nests or active wildlife before pruning
George Reno is a local arborist at The Davey Tree Expert Company in Menlo Park, which serves communities on the Peninsula, including Menlo Park, Atherton, Palo Alto and Redwood City. Reno can be reached at 866-923-5658.
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