One of the more common questions asked by newer gardeners is, “when is the best time of year to prune my __________?” The answers out there can vary from “the first hearing of tree frogs after the second full moon past the Summer Solstice” to “anytime your pruning shears are sharp.”
Here in the Maritime Northwest, we recommend that most pruning be done during summer and winter, and minimize it during fall and spring, which are more sensitive periods when the sap is flowing. In warmer or colder climates (particularly where more extreme), timing recommendations may differ, depending on how local plants grow, when they bloom, etc. It’s best to check with local resources before establishing your pruning schedule.
Keep in mind that these are general recommendations. Appropriate timing for pruning is helpful, but perhaps not critical to a plant’s health and performance. Young trees and shrubs, fruit-bearing plants, and delicate flowering plants may be more sensitive but generally, a healthy plant can tolerate pruning almost any time, outside of periods of extreme heat or cold. Dead branches and twigs can me removed any time, of course. And most plants don’t require pruning every year if they are grown in an appropriate space.
More important is how much you prune off at one time and where you make your cuts (visit our post Pruning 101 for details). With experience — and by keeping your pruning moderate and gradual — you will avoid major mistakes or overreactions, learn what your plants can tolerate, and establish your own rhythm.
SPRING
Spring is a dynamic, and therefore, delicate season for pruning. It’s when plants are leafing out, sap is most active and pruning can disrupt fragile new growth, flowering, nesting birds, or pollinators. It might help to think of early, mid, and late spring as three phases for pruning before, during, and after the primary growing period. Then avoid or minimize any pruning in mid-spring.
A general principle is that pruning before the primary growth season tends to accelerate growth, whereas pruning after that season tends to slow it down. There are exceptions, depending on species of plant and how healthy or vigorous an individual plant might be.
Early spring (typically between late February and early April in our region) is okay for cutting back perennials, ornamental grasses, vigorous shrubs (unless they are spring-blooming), and hybrid roses. Any major, aggressive pruning you deem necessary is better done in early summer, or winter as described later.
Mid spring (April and May) is okay for light thinning or corrective pruning of a tree or a young plant, along with cutting some branches for flower displays. But again, keep this pruning minimal.
Late spring (June) is when you can prune plants that have finished blooming and cut back more vigorous growth, although some growth might not slow down until early July around here.
So if your garden tends to go crazy each spring, wait for summer to do most pruning. But for some aged or struggling plants that seem to lack vigor, a hard pruning in early spring may give them a jump start. Also, if your English laurel or other fast-growing, coarse-branched hedge needs a major cutting back, doing so in early spring can help it regrow quickly and minimize the “chopped” look, although it might still need some additional pruning in summer.
Early spring pruning of roses.
Which plants to prune in spring?
Early Spring:
• Hybrid roses
• Smokebush
• Twig dogwood
• Lavender
• Heather (winter-blooming)
• Ornamental grasses
Late Spring:
• Rhododendron
• Camellia
• Forsythia
• Mock orange (Philadelphus)
• Witch hazel
Late spring pruning of forsythia after blooming.
SUMMER
Summer is good for fine tuning and decluttering. You can thin out congested trees and shrubs to allow more sunlight and air circulation. Head back aggressive outer shoots that look awkward. Remove water sprouts (fast-growing vertical branches out of character with the rest of the tree) and basal suckers (similar but growing from the trunk base or roots). Thinning out fruit clusters such as on apples, plums and grapes can yield larger fruits. And you can prune almost anything that won’t be blooming in late summer or fall.
Deadheading (removing spent blooms) on heavy bloomers such as rhododendrons and lilacs can help clean up their look and direct energy into next year’s flower buds. However, on some large, mature specimens, deadheading can be time-consuming and increase blooming only minimally.
Early summer deadheading of a rhododendron.
Be aware of our common summer droughts in the Northwest. We often receive little rain between mid-July and mid- or late September, which can stress many plants. Many of these benefit from deep watering during the summer months. But if the summer is projected to be drier than average, and you have a plant that needs a major pruning or is in delicate health, it might be best to do that earlier (June) or save it for late winter.
Lilac ready for summer pruning.
Which plants to prune in summer?
• Flowering trees (cherry, plum, crabapple, dogwood)
• Magnolia
• Japanese maple
• Fruit trees (for thinning branch density and fruit clusters)
• Shade trees
• Lilac
• Camellia
• Rhododendron
• Viburnum
• Roses (light thinning and deadheading)
Summer thinning of a Japanese maple.
FALL
Mirroring the spring routine, we minimize pruning in fall (typically between about mid-September and late November) to avoid stimulating new growth as the sap is retreating to the roots to store energy. But some light thinning and clean-up pruning is fine.
Fall is also good for removal of clinging or fallen leaves and fruits, especially if disease is a concern (such as on roses and fruit trees).
Whether to cut back dead material in fall (especially on perennials and grasses) is largely your aesthetic choice. Many gardeners appreciate the look of dried seed heads and stems, and wildlife also can benefit. You can choose to wait until they deteriorate later in winter before pruning.
Which plants to prune in fall?
• Lavender (deadhead wands but minimize cutting into foliage)
• Salvia
• Catmint
• Bluebeard
• Roses (deadheading & clean-up)
• Vines (deadheading & clean-up)
• Hydrangea (optional: deadheading & clean-up)
Lavender ready for fall deadheading and clean-up pruning.
WINTER
Winter is a good time for major thinning and decluttering, as well as pruning fruit trees and late summer/fall blooming plants. It’s good for thinning and heading cane-type shrubs, renovating old or overgrown plants, and clearing out invasives such as ivy and blackberry. It might help to think of late fall/early winter pruning as visual clean-up for the winter months, and late winter/early spring as making way for spring growth.
Ornamental grasses can be cut back, and shrubs such as redtwig dogwood thinned or cut back in late winter.
Be aware that some trees such as maple, birch, and dogwood have running sap which can “bleed” from fresh cuts during warm spells and the latter part of winter. There is lack of conclusive evidence that this actually harms a tree, except perhaps large cuts during a hard freeze/thaw cycle. But to avoid it, you can prune earlier in winter, or wait until summer.
Which plants to prune in winter?
• Fruit trees
• Shade trees
• Summer-flowering trees (such as smokebush, crape myrtle, golden rain)
• Japanese maple
• Twig dogwood
• Shrub hibiscus
• Shrub willow
• Hydrangea
Winter pruning of an apple tree.
Pruning Specific Plants
If you have questions related to timing or other pruning details for specific plants, we have several blog posts and care sheets that may help:
Winter Pruning of Ornamental Grasses
Promoting Wisteria Bloom: Part I
Still Not Sure About Timing?
If your plant just doesn’t seem to fit into nice, clean categories, then ask yourself:
When does it bloom? Then prune it within a month or two after it finishes blooming.
How aggressive of a grower is it? If it sprouts and grows vigorously and you feel the need to keep it in bounds, prune it toward the end of its growth spurt (typically June to early July). Or you might want to prune some of it in summer and some in winter. If it’s a naturally slow grower you can prune it almost anytime (while considering bloom time, if applicable).
Again, if you keep your pruning moderate and gradual, you should be able to avoid any major problems and keep your plant looking healthy and beautiful throughout the seasons!
Of course, you can always ask us! Contact us or stop in to talk with one of our nursery professionals.