Quick answer: The best time to prune most trees in Denver is late winter, from mid-February through early March, while the tree is still dormant. That is the Colorado State Forest Service’s recommendation. Dead, diseased, broken or hazardous branches can be removed at any time of year.
Timing affects how fast a tree closes its wounds, how much it flowers and how easily disease gets in. This guide gives the timing by tree type. For the service itself, see tree pruning and trimming in Denver.
When should each type of tree be pruned?
| Tree type | Best time |
|---|---|
| Shade trees (maple, oak, honeylocust, elm) | Late winter, before buds swell |
| Fruit trees (apple, pear, plum, cherry) | Every year in late winter or early spring |
| Crabapples | Late winter, or straight after bloom and before June 1 |
| Newly planted trees | Only dead, damaged or crossing branches |
| Any tree with dead or broken limbs | Any time |
Why is late winter the best time to prune?
The Colorado State Forest Service explains that trees are still dormant in late winter and that wounds close quickly when pruning is done just before new growth starts. That is not true of early winter cuts, which sit open for months. With no leaves on the tree, the branch structure is also easy to see, so the right branches come off.
Is it a problem if the tree bleeds sap?
No. Elms, maples, birch and walnut can drip sap when they are pruned in late winter or early spring. The Colorado State Forest Service says this should not harm the tree. If you would rather avoid it, a CSU Extension horticulture agent suggests pruning those species in midsummer, after the spring growth flush.
When should fruit trees and crabapples be pruned?
CSU’s PlantTalk Colorado advises that most fruit trees benefit from pruning every year in late winter or early spring, because pruning before leaf-out helps prevent the spread of disease. For crabapples, CSU Extension says pruning should be finished by June 1, since next spring’s flower buds form in June and July. Crabapples, apples and pears are prone to fire blight, a bacterial disease that travels on pruning tools, so tools should be disinfected between cuts.
Can you prune in summer or fall?
Light pruning is fine. CSU Extension guidance is that removing less than about 10% of a tree’s foliage can be done at any time of year. Heavier pruning is better left for late winter. How much can come off in one visit is covered in tree pruning vs. tree trimming. Most arborists avoid major cuts in fall, when the tree is shutting down and wounds are slow to close.
What about storm damage?
Broken and hanging limbs do not wait for the calendar. After one of Denver’s heavy, wet snowfalls, damaged branches should be removed as soon as it is safe, and the rest of the tree can be tidied in late winter. See storm damage tree cleanup. Booking in late winter also avoids the storm rush, which helps with tree trimming cost. Pruning on a regular cycle before the snow season is the best protection: see how often to trim trees in Denver.
Tree pruning timing FAQs
What month is best to prune trees in Denver?
Mid-February through early March is best for most trees, according to the Colorado State Forest Service. Trees are still dormant and wounds close quickly once growth starts.
Can I prune trees in summer in Denver?
Yes, lightly. CSU Extension guidance is that removing less than about 10% of the foliage, and any dead, diseased or damaged wood, can be done at any time of year. Save heavier pruning for late winter.
Does late winter pruning hurt trees that bleed sap?
No. Elms, maples, birch and walnut may drip sap after late winter pruning, but the Colorado State Forest Service says this should not harm the tree.
