Late-Winter Pruning Guide: What to Cut Back Now

What to Prune in Late Winter

In late winter, prune most deciduous trees, fruit trees, and the shrubs that flower in summer on new wood. Leave spring-blooming shrubs such as lilac and forsythia until right after they flower, and finish oaks by the end of February. Iowa State University Extension puts the window for most trees at February through March, the late dormant season, and for fruit trees in Iowa at late February to early April.

The timing has a practical advantage. Purdue Extension and University of Illinois Extension both point out that the branch structure is easier to see without leaves, so crossing and crowded limbs stand out. Young fruit trees follow their own sequence of cuts, laid out in the guide to pruning a young apple tree.

Plant group	Late-winter action	Window given by the source
Most deciduous trees	Prune	February through March (Iowa State)
Oaks	Prune early or wait a year	December, January, February (Iowa State)
Fruit trees	Prune	Late February to early April in Iowa (Iowa State)
Summer-flowering shrubs	Prune	Late winter or early spring (Iowa State)
Juniper and yew	Prune	Late March or early April, before new growth (Iowa State)
Spring-flowering shrubs	Leave alone	Immediately after flowering (Iowa State)

These months come from Midwestern sources. University of Wisconsin Extension notes that by late March or early April the dormant window is almost closed in much of Wisconsin. In other regions, shift the months to match your own dormant season, since each of these windows is defined by the plant being dormant.

The Rule for Flowering Shrubs: Old Wood or New Wood

One question settles every flowering shrub. Does it bloom on stems that grew last year, or on stems it will grow this year?

Shrubs that flower in spring carry their buds through the winter on old wood. Purdue describes the cost of winter pruning on early bloomers such as magnolia, lilac and azalea plainly: you prune off flower buds. Wisconsin adds mock orange and weigela, and Penn State Extension Master Gardeners add forsythia and rhododendron. Prune these right after the flowers finish, which leaves the rest of the season for next year’s buds to form.

Shrubs that flower in summer bloom on wood that does not exist yet, so cutting now costs nothing. Wisconsin lists Japanese spirea, shrub hibiscus and panicle hydrangea. Clemson’s Home and Garden Information Center lists butterfly bush, crape myrtle and rose of Sharon in the same group.

Hydrangeas fall on both sides, which is why they cause the most mistakes.

Hydrangea	Flowers on	When to prune
Smooth	New wood	Late winter or early spring
Panicle	New wood	Late winter or early spring
Bigleaf and mountain	Old wood	Just after the flowers fade
Oakleaf	Old wood	Just after the flowers fade, if at all

University of Maryland Extension notes that smooth hydrangea can be trimmed to about 12 inches off the ground, and that panicle hydrangea can be taken to the same height or left taller. Penn State gives February and March as the months for smooth hydrangea. Cutting an old-wood hydrangea in late winter removes its flower buds, one of the causes covered in why a hydrangea is not blooming.

Trees That Need Different Timing

Oaks are the main exception to the February and March rule. Iowa State names December, January and February as the best months, and Illinois warns that oaks should not be pruned from March through October, to reduce the spread of oak wilt. Wisconsin ties the risk to temperature. The beetles that carry oak wilt and Dutch elm disease become active at 50°F, so oaks and elms should be pruned only when temperatures will stay reliably below 40°F for several days before, during and after the work. If a mild spell has already arrived, leave oaks and elms until next winter.

Some trees leak sap heavily from late-winter cuts. Purdue lists maple, birch, yellowwood, dogwood, beech and hornbeam, and Maryland’s list adds elm and walnut. Maryland states that this bleeding is not harmful to the tree. If the dripping bothers you, Maryland suggests pruning those species in November and December, or in May or June after the spring growth has finished.

Dead, dying and broken branches are outside all of these calendars. Illinois says any time is a good time to remove them.

Renewing Overgrown Shrubs

Late winter is also when to deal with a shrub that has become a thicket. Iowa State gives March or early April as the best time to rejuvenate large, overgrown shrubs. There are two ways to do it.

The gradual method removes the oldest stems at the base and keeps the shrub’s shape. For red-twig dogwood and shrub willows, Wisconsin recommends taking out about 30% of the biggest, oldest stems right at ground level. Penn State describes a slower version carried out over three years, removing 15% to 20% of the oldest and tallest branches each year.

The hard method cuts everything down at once. Clemson defines renewal pruning as cutting the plant back to within 6 to 12 inches of ground level, and says the best time for a cut that severe is before spring growth begins. A spring bloomer treated this way will skip its flowers for the year, which is the price of starting over.

For routine pruning, Penn State’s limit is a useful brake: do not remove more than 1/3 of a shrub’s branches or height at one time.

Making the Cuts

Where the cut lands matters more than how much comes off. Illinois notes that a plant seals a wound properly when the branch is cut at a node or at the branch collar.

To shorten a stem, Clemson’s instruction is to cut on a slight slant one-quarter inch above a healthy bud. The bud should face the direction you want the new growth to take.

A heavy limb needs three cuts so its weight does not tear bark down the trunk. Maryland describes them:

1. Saw upward halfway through the branch, about a foot beyond where it meets the trunk.
2. Saw downward all the way through the branch, somewhat farther out than the undercut. The limb drops and the undercut stops the tear.
3. Make the finishing cut on the branch side of the collar, the thickened area where the branch joins the trunk. Maryland describes the collar as tissue that encourages rapid sealing of the wound.

Do not paint the cuts. Maryland says wound dressing, paint or shellac should not be applied over cut surfaces, and Purdue calls dressing neither recommended nor required apart from its oak wilt exception.

On a tree, Maryland caps removal at one-fourth of the living crown at any one time, and warns never to top a shade tree to control its size.

Tools and Stopping Points

Clean blades between plants. Illinois recommends a 10% bleach solution or undiluted 70% isopropyl alcohol. When cutting out diseased material, Wisconsin goes further and advises disinfecting shears with rubbing alcohol after each cut instead of only between plants. Sharpening is part of the same pre-season job, and the guide to sharpening pruners and loppers walks through it. If last season’s pruners came out of the shed spotted, the guide to removing rust from garden tools covers the repair.

Stop when the buds open. And do not try to catch up in late summer: Illinois warns against pruning deciduous shrubs then, because it encourages a flush of new growth. Clemson gives the same caution for late fall and midwinter in its region, where new growth pushed by pruning can be injured by cold.