Do Your Shrubs Need Renewal Pruning?

If garden space is limited or if you want to maximize the visual impact of certain fast-growing shrubs, a hard cutback every year or two serves as a reset for the following season. In general, vigorous shrubs with a suckering growth habit can take regularly scheduled renewal in stride.

‘Ogon’ spirea (Spiraea thunbergii ‘Ogon’, Zones 4–8) is an early-spring bloomer with delicate white flowers and beautifully fluffy chartreuse foliage all summer. Older plants have a tendency to sprawl and get leggy, but winter renewal pruning would remove the flower buds that form on the previous season’s wood. My solution is to let it bloom its heart out in early spring, then whack it to the ground as soon as the flowers fade. It rewards this harsh treatment with vigorous, dense growth that looks good all summer, and it will set next year’s flower buds in autumn. A big spring chop might happen every year (or two, or three). The frequency depends on my mood, what I have planted too close, or what I removed last fall.

Renewal pruning can rejuvenate plants

If you’re an obligate plant collector with a small home garden, like me, renewal could be the key to fitting in a few more great finds. My ‘Hartlage Wine’ sweetshrub (Calycanthus raulstonii ‘Hartlage Wine’, Zones 5–9) is a vigorous grower that wants to be about 12 feet tall and wide, but I simply don’t have that much space. So, after it grows and flowers from early summer until about July 4, it gets cut all the way to the ground. By the end of the growing season, it will put out 3- to 4-foot-tall shoots containing next year’s flower buds, a kind of sloppy equilibrium allowing me to enjoy a plant I wouldn’t otherwise be able to have.

Popular shrubs that are candidates for regular renewal pruning:

• Red osier dogwood (Cornus sericea and cvs., Zones 3–7)
• Common lilac (Syringa vulgaris and cvs., Zones 3–7)
• Mock orange (Philadelphus spp. and cvs., Zones 3–8)
• Dappled willow (Salix integra ‘Hakuro-Nishiki’, Zones 5–7)

Red osier dogwood. Photo by Jack Coyier	Common lilac. Photo by David McClure
Mock orange. Photo by Jack Coyier	Dappled willow.

Sometimes older shrubs can become a bit long in the tooth and shy on vigor. If you are considering a hard reset on an overgrown or improperly pruned shrub, remember that deciduous plants should generally be pruned when they are dormant, while evergreens should be pruned in mid-spring, after the risk of frost has passed and the plant is actively growing.

Any gardener who has maintained a formally pruned hedge knows the signs of decline: plants with empty centers, no new side growth, and just a thin veneer of new growth on top. A shrub with vertically sheared sides will be much more likely to develop this hollowed-out look than one with a more natural tapered shape, wider at the bottom and narrower at the top.

A few considerations before you start cutting

If you’re thinking about rejuvenating a shrub that has become tired and worn out, first confirm that it has the potential to sprout new growth from internal branches. Yews (Taxus spp. and cvs., Zones 4–8) and some rhododendrons (Rhododendron spp. and cvs., Zones 4–9) are good candidates for judicious renewal pruning, while most coniferous evergreens are not.

The following techniques won’t look pretty in the short run but could bring life back to a plant that needs some love. Speaking of love, you might want to run these options past your gardening and/or life partner before taking any drastic action.

Take a deep breath and lop off enough of the shrub’s top to expose the bare center of the plant. If done correctly, this procedure should make your heart skip a beat or two. But if your plant is otherwise healthy, the increased light reaching its center should help to encourage new growth for a fuller, more balanced look within a few years.

Pruning Option 2: The Side Chop

Rather than focusing on taking off the plant’s top, you can accomplish essentially the same thing, one side at a time. Taking off the top branches of just one side will stimulate new, internal growth, just like the Top Chop. But it also allows you to adjust the shape of the plant over a couple of years, which is especially important if it is in a prominent location or used for screening. If the sides of the shrub don’t currently have sufficient vertical slope to allow sunlight to reach the base, the Side Chop is a great option.

While the most aggressive among us might be tempted to Side Chop both sides in the same growing season, the better move is to do one side the first season and then the second side a year or two after. That leaves the top and one side with plenty of green to fuel recovery.

The best plants for either the Side Chop or Top Chop will be healthy, robust growers that can take hard pruning cuts on old wood; many traditional hedging species fit this category.

Plants that can take the Top Chop or Side Chop pruning method

• Ninebark (Physocarpus spp. and cvs., Zones 3–9)
• Elderberry (Sambucus spp. and cvs., Zones 3–9)
• Holly (Ilex spp. and cvs., Zones 5–9)
• Willow (Salix spp. and cvs., Zones 4–9)

Ninebark. Photo by Jack Coyier	Elderberry. Photo by Jack Coyier
Holly. Photo by David McClure	Willow. Photo by David McClure

Whether you are trying to maintain the sharp lines of a sheared hedge or transition your shrubbery to a softer, hand-pruned look, the Selective Snip is a gentler approach—at least for your heart.

Put away the hedge shears, grab your hand pruners, and cut selected branches back to their point of origin, deep into the top and sides of the hedge. You are essentially poking holes in the solid green shell of foliage, leaving the overall structure of the plant in place. Although it won’t look as severe as either of the other two methods (or a complete cutback to the ground), it may not be much more pleasing to the eye of a non-gardening partner or neighbor. Give the plant the best chance of recovery by removing one in three mature branches, or fewer.

Taking out a selection of the oldest and largest branches over the course of three or more years is a gentle way to bring new life back to shrubs that might not respond as well to a drastic cutback.

Plants that benefit from gradual rejuvenation pruning

• Shrub rose (Rosa spp. and cvs., Zones 3–9)
• Abelia (Abelia spp. and cvs., Zones 4–9)
• Mahonia (Mahonia spp. and cvs., Zones 5–9)
• Currant (Ribes spp. and cvs., Zones 3–8)
• Camellia (Camellia spp. and cvs., Zones 6–10)
• Hebe (Veronica spp. and cvs., Zones 7–10)
• Multistem magnolia (Magnolia spp. and cvs., Zones 3–9)

Shrub rose. Photo by Ryan Riley
Abelia. Photo courtesy of Proven Winners ColorChoice	Mahonia. Photo by David McClure
Ribes. Photo by Ryan Riley	Camellia. Photo by Jack Coyier
Hebe. Photo by David McClure	Multistem magnolia. Photo courtesy of Bailey Nurseries