How to Prune Flowers, Trees, and Shrubs
Too many gardeners let a timid spirit keep them from growing the most beautiful plants they could have.
I call it prunophobia, or shear fear. Sometimes it’s because of a bad experience, like a plant that died after you pruned it. Even though the effect (a dead plant) was not likely brought on by the cause you identify (your pruning), your confidence is shattered. So you stop pruning.
Azaleas grow huge, perennials seed all over the place, trees look lopsided, and the pear tree quits bearing. It’s so sad to have that nice yard look like the set of a horror movie, with your house all but hidden behind menacing horticulture.
There are other reasons people don’t prune. You’ve heard that if you prune at the wrong time of year, flowering shrubs won’t bloom. That’s true. Or a neighbor seems to spend all his time clipping something to no apparent result, so you figure it’s a waste of time. Sometimes that’s true, too.
Other plants just never seem to be at the right stage for the pruning, such as vitex and butterfly bush, although it is clear that they need it at some point.
The cure for sheer fear is already in your hands. I once took a job pruning 50 Formosa azaleas because I was young and stupid.
The onerous task was to rejuvenate them, which means removing the tallest, fattest stems all the way to the ground. At times that week, I despaired of ever finishing, much less calling the job a success, but I got it done.
The next year, I went back and crowed at their beauty and I had helped! That’s how we get over the fear of pruning: inform yourself about it, take a deep breath, and just get on with it.
Here’s what pruning can do:
- Contribute to plant health and thrifty growth. An overgrown shrub loses more than flowers, and unshaped trees look and are weak.
- Control growth. Keep plants away from wires and other hazards, exercise your choice of heights, decide how much and whether to prune crepe myrtles.
- Show off beauty with pruning to limb up a tree or shrub, cover an arbor, or maintain topiary.
- Increase and enhance new growth, flowering, and fruiting.
- Prevent transplant shock.
- Remove deadwood and hazardous or damaged trees.
We prune because we are gardeners because, unlike so many things, the shears and saws are at our beck and call. When the plants respond well, you are cured of prunophobia.
To begin sorting out what to prune and when thinking in terms of plant groups and their behavior.
Annual Flowers usually need old flowers removed (deadheading) and some types of annuals should be cut back at midseason. As the annual flowers age, they form seeds, ending the life of that plant to ensure the future of the species. When you interrupt this natural cycle by cutting the flowers off before they go to seed, the plants keep blooming.
Happily, there are self-cleaning annuals that do not require deadheading. Begonias and impatiens are wildly popular in part because of this free-blooming habit.
After a tough summer, these annuals respond well to rejuvenation. Cut them back in July to stimulate new growth, keep the plants neat, and bring on more flowers. If you want annuals to reseed, as cleome, Mexican hat, and Johnny-jump-ups do so readily, pull the mulch away from them as the flowers fade. Without good soil contact, most seeds will not survive; if you don’t want to reseed, keep the mulch pulled close.
Perennial flowers will not always rebloom, but deadheading them is still a good idea if you don’t want them to reseed. Black-eyed Susan, some coneflowers, and many daylilies do put on a second flush of flowers and they will look much better without the old stems and seedheads hanging around.
Perennials with one primary bloom per stem, like daisies, have small, modified leaves below their flower. Cut their stems down to the true leaves and/or secondary flower buds. Once the stem is done, remove it entirely so others can emerge from the clump if they will. Others, like phlox, bloom atop fully leafed stems. Removing just the flower with a short stem will often stimulate blooms from other points on that stem.
When perennials are frost-bitten, they often go dormant. A few are senescent, like Lenten rose and oxalis, growing from fall to spring and resting in summer. Remove the browned stems and rake away fallen leaves when this happens. If you don’t, the weather is sure to warm up and get rainy. The result can be a nasty outbreak of furry fungus on the stems. Even if they don’t hang around to infect future flowers, you’ll inhale the spores when you finally do cut them down, and nobody needs more allergens
A huge issue for southern gardeners is that perennials do not always take a rest. Often lantana and verbena have already started to grow at their base by the time the mature stems finally turn brown. Butterfly bush is famous for staying somewhat green all winter, but still needs to be cut down to stimulate the new season’s growth or it will become thickety with small flowers if any appear at all.
Ornamental grasses and clumping ground covers
Ornamental grasses and clumping ground covers respond well to pruning annually to keep their clumps neat and bring on flowers. Ground covers like liriope look ratty when unkempt winter-damaged growth is not removed before new growth starts.
Use a long-bladed hedge clipper to cut a few inches off ground covers and remove damaged leaves. Fountain grass and other large ornamental grasses develop an unattractive, sprawling habit unless cut down in winter. Cut the clump down to 12 inches to 18 inches tall, using a hedge shear held upside down to shape the grass into a rounded mass.
Bulbs, whether true bulbs like daffodil, or plants that act like them (rhizomes such as iris, tubers of canna, or gladiola corms) need little pruning, but we do it anyway. Spring bloomers use their green leaves to move nutrients into the bulbs, so the longer you can leave them be, the better.
Once the leaves are half-browned, go ahead and cut them off if their appearance is unsightly. Likewise, it is fine to cut iris leaves into fans to improve air circulation in the bed as summer heats it up. Bulbs like caladium and dahlia that must be dug up in parts of the south and stored to ensure their survival will be best left to turn completely brown. Then trim off their foliage and proceed.
First, read our very detailed piece on how to prune roses.
Here’s the deal on roses. They fall into two main types, hybrid teas and everything else. If you don’t know what kind yours are, look at how they’re meant to grow. Hybrid teas have thick canes, usually with one cut-flower quality rose atop each stem. To get two rounds of these flowers, prune hybrid tea roses twice each year in mid-February and late July. Cut the canes down to 18 inches tall in winter, two feet in summer.
The other roses grow like shrubs, with many stems and flowers on each plant. Usually, they are lumped together and called shrub roses, old garden roses, antique roses, and other names. Some are all of those things! But they don’t all need the same pruning.
Once-bloomers usually put on quite a show in spring, then grow grand green leaves and new canes all summer. Prune them after they bloom to shape and control growth. Remove the oldest canes entirely to ground level so new ones can thrive. Next year’s roses will flower best on this year’s strong new canes.
Climbers should be pruned like once-bloomers but in fall. There are roses like ‘Mermaid’ that are huge and will continue to bloom without pruning. Unfortunately, these roses will also climb over your garage if you don’t control them. Use jute to tie climbers to the front only of the structure. Avoid the temptation to weave the canes around pieces of jute or wire. In the fall, cut the jute and let the canes down on the ground. Prune for height and shape, and remove canes as they grow woody with age. I know this all sounds ominous, but do it once and the results the next year will stun you.
Low-growing, ground cover type roses are free-flowering and need to be pruned only to remove deadwood and canes with a strongly upright habit.
Vigorous reblooming (remontant) shrub roses
Vigorous reblooming (remontant) shrub roses will outgrow their space with weak growth and fewer flowers unless they are pruned hard in February. Cut off everything except the main canes and remove any of those that are weak or badly placed. Then cut the main canes down to about two feet tall.
The idea is to push new growth to about the same height each year. When in doubt, prune these a bit more. With deadheading, they will flower several times beginning in spring. You can prune a few inches off in late July if necessary to neaten up the plants and spur on new growth and more flowers. This group includes the Texas found rose ‘Caldwell Pink’, ‘Bourbons’, ‘David Austins’, noisettes, standard size ‘Meidiland’ varieties, and many more. If February gets by you one year and the roses start to grow, leave them be and prune harder in summer.
A few types of individual roses hardly ever need pruning except to remove deadwood and old flowers so more can replace them. You can cut off some of their height in winter and in summer between bloom flushes. China roses (‘Archduke Charles’) and most of their relatives in the floribundas are in this group, as well as the butterfly rose.
Trees of all kinds need to be pruned while they are young to shape their growth and encourage sturdy trunks. Yes, they’re small, but squint if you must and imagine them fully grown. Remove branches that crisscross the canopy or each other, and any weak wood, especially small branches low to the ground.
It’s important to take a look at trees each year, no matter their age, and prune for strength. In the case of single trunk trees with lots of side branches like Bradford pear, limit the number of branches you allow to develop. Better air circulation around the major stems and less weight on them can work against their natural tendency to split in half in a strong storm.
Crepe myrtle is an example of a tree that responds to deadheading. It should be trained while young and can be pruned heavily in winter. Find more info on crepe myrtle behavior and treatment in a special section on the South’s favorite tree.
Flowering trees can be pruned after flowering has finished to shape the trees and encourage new growth.
Evergreen trees can be clipped and shaped in late winter, just as their new growth is beginning.
Shrubs may be the perfect plants to cure shear fear. Evergreens are the simplest to figure out, especially those that make berries or other winter fruit. After the birds have feasted in late winter, you can cut back mature evergreen shrubs by as much as one-third of their overall size in one year without harming them. Young evergreens will grow thicker if you will prune a few inches off in late winter and in early June for the first three years or so. After that, you can continue pruning, or not, as their appearance and your mood dictates.
If you must deal with overgrown shrubs, look before you bring in the chainsaws. You can limb up most of them, creating small trees. By pruning everything off the trunks up to a crown of a canopy, you gain a quality specimen that would cost a pretty penny to buy. Better yet, you honor that aging beauty.
When other considerations preclude limbing up, most evergreens can tolerate being cut back by as much as half. The result will be ugly, but with time and ample amounts of water and fertilizer, rejuvenation will work.
Flowering shrubs are pruned based on their growth habit and flowering time. Before you prune any of them, first think of when they bloom.
Spring blooming shrubs
Spring blooming shrubs that bloom on one-year-old wood growing off the older wood will hold their flowers up in the shrub. Prune right after they bloom to thin the wimpiest of shoots on young shrubs, to remove twiggy old growth in older ones, and to remove errant shoots. Take a few inches off each branch annually to keep the plants healthy, properly sized, and flowering. This group includes forsythia, mock orange, weigela, and most of the spireas.
Flowering shrubs that bloom on one-year-old wood that grows right up from the base of the plant or near it can be pruned in one of two ways. Cut back to near ground level or too vigorous branches coming from the base of the plant such shrubs as kerria and abelia whenever they become twiggy or fail to bloom.
Camellia and azalea
Camellia and azalea are the best examples of why we prune flowering shrubs within a month after they bloom. Winter and spring’s showiest ladies begin to set buds for the next year almost immediately. If you prune later than a month after the flowers fade, you cut them off, and, no doubt, suffer a relapse of shear fear.
A few flowering shrubs bloom entirely on the current year’s wood, such as a chaste tree, Japanese beautyberry, St. John’s wort, and butterfly bush. It is a challenge to prunophobics to cut these back as drastically as they need, but worth it when new growth bursts into flower.
Many kinds of hydrangeas have found their way into our hearts and gardens. Here is how to prune them.
Once-blooming Frenchies or mopheads have been garden stalwarts for years, but our attitude toward them has changed. Where my grandmother cut them back hard each January, such drastic pruning is not necessary or desirable except to rejuvenate very old shrubs.
Instead, like the lacecaps, we prune French hydrangeas in winter to remove old flowers left on the shrubs. Clip the stem off behind the flower down to the next bud and remove any weak wood in winter. More often, once-blooming French and lacecap hydrangeas need only be pruned after they bloom to shape the shrubs and remove the oldest branches and those that are trailing on the ground.
Reblooming hydrangeas develop new flower buds on both last year’s wood (old) and this year’s new growth. Prune them only to deadhead the flowers and shape the shrubs during the growing season.
Oakleaf hydrangeas can be treated like mopheads and lacecaps. They do not have to be pruned at all but can be to remove aging flowers and to keep new growth healthy. You can remove the oldest stems completely every few years so new ones will keep coming up. Do not prune any of the hydrangeas after midsummer, or you risk losing the flowers for next year. Prune as needed before that, even while the shrubs are in bloom if necessary.
Reblooming shrubs, such as Encore azalea and loropetalum, can be pruned after the first flush of flowers in the spring. Despite the rule about not cutting buds off, rebloomers will flower again in the same season if you prune them. Like 21st century hydrangeas, they bloom on old and new wood.
Tools for Pruning
Every authority says to select a superior tool and keep it forever, but I am unable to resist a new kind of handle or blade material. Traditional clippers and pruners with their straight handles make you use repetitive motions and work you harder than is necessary!
Once I moved to padded handles and ratcheting action to lower the impact on my wrists, I never looked back. Currently, I use a ratcheting hand pruner for stems about half an inch in diameter, a straight line clipper with padded handles for smaller stems, and a long-handled clipper that works by squeezing its handles together.
This last enables me to reach nearly two feet to prune without stooping. Also in the greenhouse are serrated scissors, straight edge scissors, a pocket knife, and a grafting knife seldom used for its original purpose but excellent for cutting jute string.
Loppers and shears
A lopper has two curved blades set to slice through woody stems when brought together by the action of two handles. I use two sizes of loppers, one small, and two that are much larger. One of the larger loppers looks traditional with a blade that can cut a branch almost two inches in diameter.
The other has a fantastic ratcheting head, allowing me to reach into or under a plant to prune it without contorting or overworking wrists and elbows. Hardly anyone uses grass shears anymore, those spring action long skinny blades that cut crosswise.
They are useful for cutting back grassy plants and keeping short borders neat. Their big brother, the two-handled, cross-motion hedge shears, have no equal for shaping flowering shrubs, cutting back large grasses, and keeping evergreens neat. This is one tool I can maintain and so can you: the blades have a strong edge that is easy to sharpen with a small file.
Saws, short and long
Two saws compete in my garden for the title of Most Used, a nine-inch folding saw and a telescoping pole pruner that reaches 15 feet over my head. It is amazing what you can cut with such a small folding saw. Other saws are handy at times, as is an axe and a pick.
Power to strength ratios
Though I use hand tools the vast majority of the time, my experience does include the big guns of the pruning world. When the branch to be pruned is too large or the job too extensive for hand tools to be practical, power tools amplify muscles nicely. Wear earplugs and safety goggles, please, whenever employing chainsaws and power hedge shears. And be aware of the decibel level you and your neighborhood can tolerate.
Hauling made easy
Carrying a tarp with you as you prune or groom plants just makes sense unless you have elves that come behind you to clean up. For big jobs, cut a large branch first and use it as a litter for everything else. Position the major piece of debris so its trunk or stem becomes your handle. Even with a tarp underneath, hauling is much easier.
Litter and leftovers
Should you grind, chop, compost, make wattles and bowers, or build forts? In our generous climate, there’s lots of plant debris in even the smallest garden. It is fine to dig some of the lawn clippings and more newly raked leaves into areas you intend to plant next year. Otherwise, compost what you can and throw away what you must. Don’t miss an opportunity to use prunings for propagation, decoration, and construction of wattle fence, bentwood trellis, garden bower, or the eight-year-old’s dream home, a fort made of hedge trimmings.
Know a pro
A licensed, bonded, insured arborist can be your best friend when grand old trees are yours to steward. Trees can hold up a hammock and shade your house, but they can also become hazards. Obviously, when damage to big old trees happens in a storm, professional attention is demanded. But other problems can evolve more subtly. You see the trees every day, and signs of distress can be overlooked. Besides being another set of eyes to watch for common problems as trees age, the arborist can tell you what not to worry about, and that may help you sleep at night.
A few professionals also provide deep root feeding; find one if you can. Alternatively, use an auger to fertilize by drilling holes around the drip line of the tree to put it where the tree’s feeder roots can reach it.
Feel Shear Fear? Check Guidelines Here!
- Change your attitude. Plants benefit from pruning and it is not hard to learn the basics.
- Pruning is created by subtraction. It is more like sculpture than anything else, where the artist envisions the result and removes everything else.
- See the line and cut to it. Look to find the growing point, the bud or node you want to be at the top of the pruned plant, then cut backwards to leave it exposed.
- You can always cut more, not less. Start at the outside of the plant, make the first few cuts, then step back, assess the result, and adjust before you continue.
- Make slanting cuts. No matter what you’re pruning, cut on a slant that slopes away from the inside of the plant. The idea here is to direct water away from the interior of the plant and train yourself to prune in a consistent manner.
Why Not to Paint Wounds
Old ideas die hard, including the use of black pruning paint on freshly cut surfaces. Some people still do it, thinking it will help the healing by keeping insects and pests out. In fact, painting seals in the anaerobic bacteria, those that need no oxygen to live in plant tissue and destroy it, leaving them free rein to do their damage.