It’s not only the grass in your yard that needs an occasional trim if you’re trying to keep your landscape looking its best.
Those bushes, hedges and shrubs in your landscape need trimming to look good and keep them strong and healthy. But giving them that much-needed haircut can be daunting.
There are many reasons to prune, says Patrick O’Malley, horticulture specialist with the Iowa State Extension in Van Buren County.
“One is to shape the plant so it’s better-looking,” he says. “You can prune it to encourage flowering.”
Sometimes pruning is to keep the good, formal look of a hedge, O’Malley said, and sometimes shrub trimming is needed it from blocking a window or to keep it from shading out other nearby plants. It can even encourage lush new growth in an older bush that’s not growing well.
“Pruning is considered by some horticulturists to be both a science and an art,” according to the University of California Extension guide to pruning.
The science is in understanding the plant. The art is in seeing the beauty of the plant in how it responds to pruning, giving it a natural shape. That’s right: A well-pruned landscape will look natural.
“Good pruning is essentially invisible,” the California guide says. Having to remove a lot of dead wood or continually trimming shrubs that are growing at a high rate may mean the plant is a bad fit for the landscape.
So how do you make sure you’re helping and not hurting your landscape when you start chopping off limbs?
Before You Start
There are a few things you need to do before you start hacking at branches or giving your boxwoods a haircut.
First, know what you have. O’Malley recommends picking up an extension publication on the particular type of bush or shrub to figure out the appropriate pruning regimen.
Make sure you have a plan as to what you want the landscape to end up looking like.
Second, sharpen your shrub pruning tools.
“It’s good to have sharp tools, whether a pruning saw, loppers or pruners,” O’Malley said.
Dull clippers, hedge trimmers, hand pruners and hedge shears will create a jagged cut more prone to peeling or decay than sharp clean cuts.
Purdue University Extension lays out safety rules you should follow before trimming bushes or pruning your landscape:
- First, call in a professional arborist for large trees or jobs you don’t have the equipment for.
- Keep all your equipment sharp and in good repair, using equipment only for the job it was designed to do.
- Always be aware of electric lines. If a power line is touching a tree limb, call the power company and stay clear of the tree.
- Never climb a tree without a safety rope, even when using a ladder.
- Keep fingers clear when using hand clippers and wear eye protection while pruning and while handled pruned limbs and brush.
Choose Your Weapon
Choosing the right tool for the job will ensure you make a clean cut that both look good and keeps the plant healthy.
The Purdue guide lays out the different types of tools and when they ought to be used.
Pruning shears, or “clippers” are best for branches between 1/4 and 1/2 inch.
Lopping shears can handle branches up to 1.5 inches in diameter, a strong but lightweight tool the usually coming in sizes from 16 to 30 inches long.
For small cuts, O’Malley recommends bypass-style clippers or loppers, meaning the blades overlap and slide beside each other when they cut. The other style, anvil style, where the blade fits into a groove, he doesn’t recommend, as they tend to pinch. However, they are useful for cutting away entire branches that hand clippers can’t handle.
Pruning saws can handle the bigger stuff, anything greater than an inch in diameter, the Purdue guide says. They’re characterized by rough teeth that prevent gumming and most cut on the pull stroke for safety.
Pole pruners, either saws or lopping shears on a long pole can reach those high-up branches.
Hedge shears, either the powered kind or the long-bladed hand shears, shouldn’t be used for pruning branches, but for shaping hedges or bushes, the guide says, and chainsaws should really be used just to cut branches already on the ground.
Timing Your Bush Trimming
The Michigan State University Extension lists late winter or early spring as the best time to prune a tree or shrub, before the new growth starts up for the year.
But there are exceptions, including for maple trees, which can “bleed” sap.
But in all cases, high summer, after new growth has taken hold, is the wrong time to prune.
The main pruning season is March through July, O’Malley says, and most pruning should stop by August so that new tender growth that comes up after pruning isn’t injured by the coming winter.
But there are exceptions. Some plants, he said, can be pruned in the fall, essentially during the month of November, especially native plants.
Trimming Flowering Bushes, Hedges
Whether the plant flowers is an important factor, O’Malley explains, as different flowering shrubs will look better when pruned before flowering while others, including lilacs, will look better when flowering naturally and pruned after.
The Clemson University Extension Home and Garden Information Center notes that many common flowering trees and shrubs should be pruned before spring growth begins. Beautyberry, crape myrtle, gardenia, mimosa and nandina are all on this list.
Spring-flowering shrubs and plants including azaleas, clematis, Bradford pear and dogwoods, should be pruned after flowering, since their flower buds are produced on the previous year’s growth, not new spring growth.
The way to tell which you’ve got is to see when they flower. If it’s before the end of June, it blooms on last year’s growth; after, and it blooms on new year’s growth.
For most flowering plants, a guide from Oregon State says, prune in late winter before a plant’s new growth begins in spring, as the goal is to prune flowering shrubs at a time to minimize damage to blooming, and that depends on when the plant blooms.
Flowers that bloom in the spring are blooming on last year’s growth, the guide explains, and flowers that bloom after June are doing so on new growth.
Plants that bloom on old wood — last year’s growth — should be pruned just after blooming, to encourage strong summer growth that will translate to healthy blooms next year.
Shrubs that bloom on new growth should be pruned in late winter to promote strong new growth and in turn strong new blooms for next spring.
Check the web for a guide to plants in your region or contact a local expert like an extension agent, or someone at your local nursery.
When to prune deciduous and evergreen shrubs and just which pruning techniques to use, will depend on the plant itself-its growth habits, bloom time and condition.
Pruning is both a growth retarding process and a bud invigorating process.
Buds on a pruned plant are exposed to more sunshine, and that sunshine, encouraging new growth and leading to larger leaves, flowers and fruit.
Always remove dead or diseased limbs first, MSU notes, followed by crossing branches that are rubbing against each other.
Also try to remove as many of the branches that are growing back toward the center of the tree or shrub, as they will eventually be crossing branches that will rub.
Staying in Shape
For those homeowners with thick leafy bushes or full hedges to trim, an electric or gas-powered hedge trimmer is likely the best bet to keep the bushes neat and trim and thick with foliage.
Power tool manufacturer Stihl offers advice on trimming different style of hedges, saying the first step is to cut the sides of the hedge vertically in a sweeping arc-shaped movement.
When cutting the top of the hedge, the trimmer should be almost horizontal, with a slight angle toward the direction of the cut.
Stihl recommends using scything movements to clear clippings from the top of the hedge as you go.
It’s best to begin pruning hedge-style plants when they’re young, Clemson HGIC says, to encourage a compact growth habit.
Types of Cuts
- Thinning cut: Thinning cuts remove undesired growth, cutting unwanted branches at the point of origin to result in a more open plant. Unlike heading cuts or shearing cuts, thinning cuts won’t stimulate excessive new growth.
- Heading cuts: A heading cut is made on a branch to bring it back to a stem at that will regrow new side branches just behind the cut from existing, dormant buds. Pruning shrubs via heading cuts will keep them at the right height for your landscape, but experts say to never cut more than one-quarter of the height of a plant. Prune young plants in their first year or two within 1 foot of the ground, so stems are shortened and new growth is promoted below the cut.
- Shearing cuts: Shearing cuts are made to shape a hedge or bush without making a special effort to cut back to a bud. But since plants chosen for this type of treatment usually have many buds close together, cuts will end up near a bud anyway and will encourage robust new growth. That means shearing cuts will become a common item on your landscaping to-do list.
Making Big Cuts
Both the University of California and Michigan State University recommend using the three-cut method for removing branches larger than 1 inch in diameter.
The three-cut method eliminates the weight of the branch before you make a final cut to prevent tearing.
First, make a small cut into the bottom of the branch a few inches away from the branch collar, or support for the branch on the trunk.
Then cut from the top down, just outside of the first cut, completing the cut all the way through and removing the branch.
The third cut will be right up against the branch collar to provide a clean cut near the trunk that won’t tear or break from the weight of the branch.
Pruning Do's and Don'ts
Correct (left) and incorrect ways to trim above a bud.
Correct (left) and incorrect ways to cut off a branch.
Homeowners need to be careful when cutting and make sure there are still some dormant buds below the cut so that the plant can recover.
Sometimes when folks cut into old wood it doesn’t grow back, he said. That’s because they cut below those dormant buds, where the new growth would normally pop out after pruning.
He also noted that depending on where you live, you may be able to have your cutting composted by your local municipality or could compost the clippings in your own backyard.
But no matter what you do with the clippings, if your home landscaping has more than a lawn, you’ll need to do some trimming and pruning to keep it looking its best.