Seasonal pruning calendar for common trees and shrubs

Most pruning mistakes aren't about technique — they're about timing. Cut a lilac in early spring and you remove flower buds that formed last summer. Cut an oak in June and you open a wound right when sap beetles are flying. The fix is a calendar built on two things: whether your plant blooms on old wood or new wood, and where your climate sits in the season.

Start with the bloom-cycle rule

Before you look at a month, classify the plant.

• Spring bloomers (old wood): lilac, forsythia, azalea, and bigleaf hydrangea set buds between July and September of the prior year. Prune immediately after their spring blooms fade — winter or early-spring cuts leave you with a leaf-only shrub.
• Summer and fall bloomers (new wood): crape myrtle, butterfly bush, rose of Sharon, and panicle hydrangea flower on the current season's growth. Prune heavily during late-winter dormancy, just before spring sap flow begins.
• Foliage shrubs: boxwood, yew, and arborvitae are pruned for shape and density. Prune in early spring after the last hard freeze, with a light touch-up in early summer.

A useful shortcut: if it blooms before roughly June 15, prune right after flowering. If it blooms after, prune in late winter or early spring.

The month-by-month calendar

This is the continental-US pattern; shift it by your local frost dates.

• January: dormant deciduous trees (oaks, maples, ashes), fruit trees, and large structural cuts. Avoid spring-flowering trees.
• February: peak season. Most deciduous trees, fruit trees, shade trees, and dormant evergreens. Avoid spring-flowering trees and heavy cuts on maples that bleed sap.
• March: last call for dormant pruning before bud break; light evergreen shaping. Avoid anything already in bud or bloom.
• April: prune spring-flowering trees right after bloom; shape evergreens as new growth starts. Avoid oaks where oak wilt is present.
• May: finish late-blooming spring-flowering trees after bloom; hedge trimming. Avoid oaks.
• June: light corrective pruning, water-sprout removal, evergreen shaping. Avoid oaks and heavy structural cuts.
• July: storm-damage cleanup and light corrective cuts only. Avoid oaks and heavy summer pruning.
• Fall: cleanup and hazard removal only. Reserve major structural work for winter dormancy.

One hard rule across the calendar: dead, diseased, or dangerous branches come out any time of year. The risk of leaving them outweighs seasonal concerns.

Why fall pruning backfires

Cuts stimulate growth. New growth in fall doesn't have time to harden before cold arrives, and the wound stays open through the cold, wet season. Both are bad for the plant. Wait until late winter for anything structural.

The oak exception you can't ignore

Oaks are the biggest timing trap in the calendar. Oak wilt is a fungal disease caused by Bretziella fagacearum, and it spreads when sap-feeding nitidulid beetles carry spores to fresh pruning wounds. Those beetles are most active in spring and early summer, exactly when infected trees are producing spore mats.

• The Michigan DNR identifies April 15 to July 15 as the high-risk infection period and recommends winter as the safe pruning window.
• Iowa State University Extension advises pruning oaks only in winter, December through February, to reduce oak wilt transmission.
• Some municipalities go further. Ann Arbor, Michigan prohibits pruning or trimming oaks from March 1 through December 1, on private and public property alike.

If you must wound an oak during the risk window — storm damage, for example — research published in Arboriculture & Urban Forestry found that painting pruning cuts reduced infection rates, though the difference wasn't statistically significant. The study's authors saw no reason to change the standing recommendation to paint fresh wounds on susceptible oaks in high-hazard areas.

Sap bleeders and other exceptions

Birches, elms, and maples bleed sap from late-winter and spring cuts. It looks alarming but rarely harms the tree. If you want to limit it, prune these in the heart of dormancy rather than close to spring. Conifers are the most forgiving group — they can be pruned almost any time, though dormant-season cuts minimize sap flow and early-spring cuts get hidden by new growth.

Your seasonal pruning checklist

1. Identify each plant and note whether it blooms on old wood or new wood.
2. Look up your average last spring frost date and your USDA hardiness zone.
3. Schedule major structural pruning 2–4 weeks before the last frost, or after the hardest cold has passed.
4. Mark the oak wilt risk window on your calendar and block it out.
5. Stop stimulating tender new growth 6–8 weeks before your first fall frost.
6. Avoid pruning when temperatures are below 20°F — brittle wood and poor wound response are common.
7. Sharpen and sanitize tools between plants, and remove dead, diseased, or crossing wood first.
8. Keep notes on what you cut and when, so next year's calendar gets easier.

How the Featured Expert Can Help

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Before you cut anything this season, confirm one thing: does your plant bloom on old wood or new wood? That single answer decides whether you prune now or wait until after the flowers fade.