The "When to Trim" Calendar: A Homeowner’s Guide
One of the most common myths in tree care is that you can trim any tree at any time. While you can technically cut a branch whenever you like, doing so at the wrong time can invite disease, attract pests, or kill next year’s flowers.
To help you plan your landscape maintenance, we’ve put together this month-by-month guide to professional tree trimming.
Winter (December – February): The Dormant Season
The Goal: Structural integrity and disease prevention.
Winter is widely considered the “Gold Standard” for tree trimming. Since the tree is dormant, it experiences less stress.
Oak Trees: Must be trimmed in winter to avoid Oak Wilt, a deadly fungal disease spread by beetles active in warmer months.
Fruit Trees: Pruning apple or pear trees now encourages a vigorous “flush” of growth and better fruit production in the summer.
The “Structural Reveal”: Without leaves, our arborists can see the “skeleton” of the tree to identify cracks or crossing branches that aren’t visible in July.
Spring (March – May): The “Post-Bloom” Window
The Goal: Maximizing flowers and managing growth.
The rule of thumb for flowering trees is: Trim them immediately after their flowers fade.
Spring Bloomers: Trees like Dogwoods, Magnolias, and Cherries should be trimmed right after they bloom. If you trim them in winter, you’re cutting off this year’s flower buds!
Sap-Bleeders: Maples, Walnuts, and Birches “bleed” heavy sap if trimmed in early spring. While usually harmless, it can be messy; we often wait until their leaves are fully out to prune these.
Summer (June – August): Maintenance & Hazard Reduction
The Goal: Safety and slowing down overgrowth.
Hazardous Limbs: Summer storms often reveal weak branches. This is the time for “Deadwooding”—removing dry, brittle limbs that could fall during a thunderstorm.
Slowing Growth: If a tree is growing too fast for its space, trimming in mid-summer reduces the food-producing leaf surface, which can help slow down its expansion.
Water Sprouts: Remove those thin, vertical “suckers” that grow at the base of the tree or along the trunk; they steal energy from the main canopy.
Fall (September – November): The “Quiet” Period
The Goal: Minimal intervention.
Fall is actually the least ideal time for major trimming.
The Fungus Factor: Fungi spread their spores heavily in the fall, and fresh pruning cuts are like open doors for infection.
Avoid the “Growth Spurt”: Trimming in late autumn can trigger a burst of new growth that won’t have time to “harden off” before the first hard freeze, leading to winter kill.
Exception: Emergency removals or clearing dead limbs that might fall under the weight of early snow.
At-A-Glance: Pruning Cheat Sheet
| Tree Type | Best Time to Trim | Why? |
| Oaks | Nov — Feb | To prevent Oak Wilt disease. |
| Evergreens | Late Winter | Before new growth starts in spring. |
| Spring Bloomers | Late Spring | Right after flowers drop so you don’t lose buds. |
| Summer Bloomers | Late Winter | They bloom on “new wood” grown in spring. |
Does your tree need a check-up?
Timing is everything, but safety always comes first. If you have a branch hanging over your roof or power lines, don’t wait for the “perfect” month—give us a call today at (720) 298-7279 or use our online form for a safety assessment!
Our service areas are located throughout the Greater Denver Metro Area.
