Late winter till early spring (Feb. to the beginning of Apr.) is the best time to prune many of your trees and shrubs. With pruning season nearly upon us here is a pruning schedule for many of the commonly grown trees and shrubs.
Prune out all dead, diseased and damage branches from late winter until early spring. Also prune out any crossing branches and water sprouts.
Non-bleeders: Late winter till early spring is the best time to prune the majority of deciduous trees. At this time there are fewer insects and diseases to invade the open wounds. Another benefit of early spring pruning is that it stimulates new growth and pruning cuts are quick to heal. It is also much easier to see the shape and inspect the health of the limbs without all of the foliage getting in the way. Trees that you should prune in late winter or early spring include: Aspen, Burning bush, Elder, Ginkgo, Harry Lauder’s Walking Stick, Hazelnut, Linden, Mayday, Mountain Ash, Poplar, Willows, Holly, Hawthorn, Honey locust and more. NOTE: to avoid stem cankers, prune honey locusts when they are still dormant in late winter. If they must be pruned in summer, avoid rainy or humid weather conditions.
Bleeders: A group of trees generally not recommended for early spring pruning are known as “bleeders”. These are better pruned in summer when they are in full leaf. During late winter to early spring the sap is rising, and will “bleed” from open wounds. This does not harm to the tree but can make for an unsightly and sticky mess. Maple is the most common and famous in this group of trees, which also includes birch, beech, oaks, Walnuts, lindens, and elms. NOTE: Oaks are an exception to summer pruning. They are highly vulnerable to oak wilt, a devastating disease that can be spread through disease spores carried on the bodies of sap beetles as they feed from tree to tree. These sap beetles are attracted to fresh wounds. Prune your oaks in the winter.
Spring Flowering Trees and Shrubs:
Should be pruned shortly after the flowers begin to fade. Removing spent blooms (dead heading) helps to redirect the plants energy into making bigger and plumper blooms for next season, rather than using that energy for seed production. Examples of spring flowering shrubs include: forsythia, flowering quince, lilac, Rhododendron, azalea, beauty bush, mock orange, red bud, flowering dogwood, firethorn, Japanese snowball, magnolia, viburnum, honey suckle, and others.
Summer Flowering Trees and Shrubs:
Prune these from late winter till early spring, before growth appears. Examples include: Rose of Sharon, Snowberry, St. Johnswort, ‘Pee Gee’ Hydrangea, smooth Hydrangeas such as ‘Annabelle’, Panicle Hydrangeas (like’ Lime Light’ and ‘Pinky Winky’), Buddleia davidii and others. For Big Leaf Hydrangeas (mop heads) prune as flowers begin to fade.
Renovation and maintenance pruning are best done in late winter, while the trees are still dormant. Later on in the season, around mid-June, it is often necessary to remove excess fruit by hand when it is still very small. Fruit thinning reduces limb breakage; increases fruit size, improves colour and quality of remaining fruit, and stimulates flower initiation for next year’s crop. Most apple, pear, and peach cultivars should be thinned until the fruit are no closer than 20 cm. Plum and apricot fruits should be far enough apart that they do not touch one another when mature.
Evergreen Trees and Shrubs:
Cedars (arborvitae) and Junipers (juniperus): may be lightly pruned in early spring to remove any winter-killed, damaged or diseased plant material. If you like to keep your junipers tightly sheared do so during the dry summer months usually beginning about mid-June. Spring. Spring and fall pruning of junipers should be avoided where possible, due to the risk of Phomopsis blight and Kabatina blight. Cedars can be pruned during dry weather anytime between June and the end of August.
Spruce (picea) and Fir (abies): Typically these trees require very little pruning. Remove dead, broken or diseased branches in early spring. Both produce dormant buds along their branches. If you need to maintain their size pruning them back will provoke dormant buds to break, creating a denser foliage and new buds will be form at the cut. Prune back in the spring before new growth starts or after the new growth has hardened off.
Pines (pinus): do not have dormant buds along their stems, new growth occurs once a year from terminal buds only (tips). As these buds (called candles) enlarge in the spring, 1/2 to 2/3 of this growth may be removed each year, before the end of June (if you wait to late to do this you will not get any new buds for next year). An alternate way I use to manage the size of pines (especially mugo pines) is to completely remove the center candle, which is the longest. This makes the tree appear smaller with fewer cuts and no browning of needles.
Yew (taxus), Boxwood (boxus) and Euonymus: may be pruned during dry weather mid-May until the end of August (mid-sept. the latest). All 3 are able to be cut back hard if required. They will sprout new growth from bare wood. All 3 also can be repeatedly sheared back in a season. If your boxwood have a high population of leaf miners prune them back before the end of May (when the insect leaves the leaf to mate) and black bag the clippings to reduce the populations.
NOTE: One final note before leaving the topic of tree pruning. All pruning should be completed by the end of August to mid-Sept. to give the new growth a chance to harden off before winter. There is also a great deal of decaying fungal organisms present in the fall.
When to prune your roses depends largely on whether it blooms on old or new wood and whether it blooms just once in the season or repeatedly.
General rose pruning for all types of roses: Generally all roses should be pruned to open the center of the plant to both light and air circulation; Make your cuts at a 45-degree angle, about 1/4 inch above an out facing bud (cutting to close to a bud may cause the bud to fail and cause branch dieback). Remove any broken, dead, dying or diseased wood as well as any crossing or badly placed branches (this includes the removal of winter damaged canes back to a healthy bud); Occasionally cut a very old stem to the ground to make room for a young replacement shoot. Remove sucker growth below the graft; Remove any weak or twiggy branches thinner than a pencil. This type of pruning should be done in early spring, just as the buds are beginning to swell. When your forsythia is blooming you will know it is time to prune your roses.
Hybrid Tea Roses: These ever popular roses produces long stems with a single large flower (or small cluster) held at the tip. To begin pruning these roses first follow the general rose pruning instructions listed above. Once that pruning is completed additional pruning will depend on how large you want the plant to be and the size of the blossoms you desire. As a general rule the harder you prune back your rose the larger but fewer the blooms. Hard pruning will also produce a smaller plant that blooms later. Dead head these roses throughout the growing season to encourage additional blooms by cutting back to a five-leaflet bud. If the canes are very long they may be shortened by a 1/3 in the middle of August. Stop pruning about 6 weeks before the first expected hard freeze to give the roses a chance to harden off before winter
Climbing Roses: Have a permanent framework of older canes on which flowers are borne. During your general early spring pruning cut back flowering branches growing off the cane to about 6 in. Be sure to prune to outward facing bud. Occasionally cut a very old stem to the base or to a strong lateral. For once blooming climbers, no more pruning is required other than to shorten any overly long canes that could not be securely tied in to prevent the winter winds from damaging the plant. For rose climbers that will produce a second, more modest flush, prune them immediately after flowering, shortening branches growing off of canes to 6 in.
Miniature Roses: In early spring shorten strong growth, thin out week growth and occasionally cut away and old stem to the base. Dead head flowers after they fade.
Modern Shrub Roses: Occasionally cut away and old stem to the base. Shorten vigorous shoots originating near the ground by one-third, shorten branches to 1ft. and thin out twiggy growth.
Other Shrubby Roses: Some shrubby roses require very little pruning, others require moderate pruning while still others require more severe pruning. I cannot cover all the rose types in this short blog post. Typically though you cannot go wrong by completing the general spring pruning. Shorten trailing stems but try to preserve the natural and graceful arching growth habit. Dead head repeat blooming shrubs.
Clematis: are pruned in 3 different ways depending upon its season of bloom and whether it blooms on old wood or new.
group 1: This group contains some of the most vigorous clematis. They flower on old wood from late April to late May. Although this group does not require pruning (other than to remove deadwood), you may wish to prune in order to control its size. Any pruning should be completed as soon as flowering has finished. This group includes the Montana Group Clematis, among others.
group 2: This group contains the early and mid-season large flowered hybrids which usually begin flowering before the end of June and may flower again in August or September. These flower on both old and new wood. Prune lightly in spring when buds begin to swell, removing dead and weak stems and reducing size, if needed. The largest flowers will be produced on the old wood, while new growth will provide blooms for the late season. Group 2 can be pruned again immediately after flowering, if needed. Group 2 includes hybrid cultivars ‘The President’, ‘Bees Jubilee, ‘Henryi’, ‘Crystal Fountain’ and many more.
group 3: This group contains late flowering species and hybrids. This group flowers on new wood. Prune this group back hard to a pair of healthy strong buds at the base of the plant in spring as the buds swell. Group 3 includes hybrids ‘Comtesse de Bouchaud’, ‘Rouge Cardinal’, ‘Jackmanii’. ‘Polish Spirit’, ‘Sweet Autumn’ and many more.
Wisteria: Prune the entire plant back after flowering is finished, thinning it out well and leaving just one or two buds or nodes per branch (the branches grow off of the main stems). Get rid of any branches that hang down and spoil the shape of the plant. To force the plant to branch more horizontally, make your cuts on a down-facing bud. In mid-summer give the vine a very hard pruning to maintain desired size and shape and thin out overcrowded stems out completely. Give it a final pruning in mid-September (or when growth has ceased).Don’t prune it quite as hard this time, leave four or five nodes or buds per branch; these will form next year’s flowers and branches. This is a good time to also train in any new shoots for training along your growing support.
Virginia Creeper, Ivies, Hops Climbing Hydrangea and Perennial Sweet Peas: The bulk of the pruning should be done in late winter or early spring. Perennial sweet peas are best pruned in late autumn. Prune for size and shape. Prune out any dead, broken or diseased stems. You may also need to occasionally prune out badly tangled stems.
Photo credit: all photos taken by the author.
University of Minnesota Extension, Pruning trees and shrubs’
Mary Wilson, Michigan State University Extension
‘Stop pruning oak trees now to avoid oak wilt” https://www.canr.msu.edu/news/stop_pruning_oak_trees_now_to_avoid_oak_wilt_1
University of Illinois Extension; ‘Clematis pruning 101’ https://aces.illinois.edu/news/clematis-pruning-101
‘The Pruning Book’ by Lee Reich
Updated: April 1, 2021
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For photos: Kimberley Pacholko When To Prune Trees, Shrubs, Roses and Vines – Horticulture For Home Gardeners
For content: Kimberley Pacholko 2021, Ornamental Garden Specialist, When To Prune Trees, Shrubs, Roses and Vines – Horticulture For Home Gardeners