When is the best time to prune shrubs in Virginia?

The right time to prune a shrub in Virginia depends on when it flowers. Spring bloomers are pruned just after they finish flowering, summer bloomers in late winter or early spring, and shrubs without showy flowers most of the year. The one season to avoid for heavy pruning is late summer into early fall.

Why bloom time decides it

Shrubs that flower on old wood set their flower buds the year before they bloom.^[1] Virginia Tech's example is that a forsythia that flowers this spring formed those buds last summer.^[1] Prune it in fall or winter and you cut off the flowers. Shrubs that flower on new wood set their buds and bloom in the same year,^[1] so a late-winter cut costs you nothing.

Spring bloomers: right after flowering

The rule from Virginia Tech is simple: prune plants that flower on old wood just after they flower.^[1] That covers the familiar spring shrubs: forsythia, deutzia, lilac, viburnum, mock-orange and spirea.^[7] Pruning soon after bloom gives the plant the whole summer to grow and set next year's buds.

Azaleas follow the same pattern. To hold their size and shape, pinch off soft new shoots of vigorous plants soon after flowering.^[5]

Summer bloomers: late winter or early spring

Shrubs that bloom in summer can be pruned any time after they flower until just before they leaf out in spring.^[1] In practice most people do it in late winter, when the branches are bare and easy to see. This group includes abelia, beautyberry, butterfly bush, rose of Sharon, crape myrtle and summersweet.^[7]

Crape myrtles get their own warning. For them, the proper time to prune is late winter or early spring prior to new growth,^[3] and Virginia Tech says plainly: "Do not prune crapemyrtles in late summer or early fall"^[3] because the new shoots may freeze. It also notes that the belief that crape myrtles must be cut back hard in late winter to bloom well is a misconception;^[3] a well-chosen plant needs little more than dead and crossing branches removed.

Shrubs without showy flowers

Shrubs without showy flowers, such as yews, barberries and boxwood, can be pruned most any time of the year except late summer.^[1] For boxwood specifically, boxwood thinning can be done at most times of the year except late summer or early fall.^[4]

Needled evergreens have their own rhythm. Yew, arborvitae, cedar, false cypress and juniper are pruned in early spring, when new growth will cover the cuts,^[2] and maintenance pruning to keep them at a set size is done in summer.^[2] If one needs a hard cut, do any severe pruning of arborvitae and juniper in March or April,^[7] and stay out of the bare center of the plant.

Formal hedges

Hedges need more than one trim a year. Hedges may be pruned twice a year, in spring and again in midsummer,^[8] and fast growers may need more. Shape them so the base stays wider than the top. Our guide to trimming overgrown hedges and shrubs covers the technique.

Overgrown shrubs

Rejuvenation of overgrown cane shrubs, cutting all the canes close to the ground, is an early-spring job,^[8] done while the plant is dormant so it can regrow all season. Gentler renewal pruning, taking a few of the oldest stems out at ground level each year, is done as soon as possible after blooming on spring bloomers,^[7] and on most other shrubs in early spring while the plants are still dormant.^[7]

The season to avoid

Late summer and early fall are the wrong time for heavy pruning. Late-summer pruning will most likely encourage a flush of new shoots that may not harden off in time for winter,^[1] and that tender growth is damaged or killed by cold. The same advice applies to evergreens: avoid pruning evergreens in late summer and early fall.^[2]

Two exceptions are always fine. When storms or vandalism damage a plant, prune immediately.^[2] And in winter, minor winter pruning for decorations usually causes no harm,^[2] so cutting some holly or evergreen boughs for the mantel is not a problem.

A note on boxwood

In Virginia, boxwood blight symptoms typically appear in late summer and fall,^[6] and the fungus spreads in wet conditions. Whatever the season, avoid working in boxwood when the foliage is wet,^[6] and clean your tools between plantings. If yours are already browning, read why boxwoods turn brown before pruning.

Stop and call a pro if

• The hedge top is out of reach without a powered trimmer on a ladder.
• Branches have grown near or into overhead power lines.
• The shrub needs saw work on trunk-sized stems, or removal.
• Boxwood shows leaf spots, black stem streaks or sudden leaf drop.

If you would rather hand the calendar to someone else, see whether it is worth hiring someone to trim your shrubs and what hedge trimming costs in Virginia. Browse more lawn and landscaping answers, see hedge and shrub trimming services, or look up lawn and landscaping businesses around Blacksburg. To get a seasonal plan quoted, describe the job once and local businesses quote it.