When to Prune Trees and Shrubs

Every year, many people are faced with the question of when to prune trees and shrubs. Of course, it is best to consult a professional before deciding on any major work to be done. However, if you’re unsure about what type of tree or shrub you have, then take a look at this helpful guide that will break down the process for you! 

Every year, we see a lot of questions about when to prune trees and shrubs. It is important to know what type of tree or shrub you have before deciding on that timing. For example, it’s not too late to prune your lilac bush if you live in the south! The best time for most people is right after flowering has finished and no later than early Fall. 

When do you know it’s time to prune your trees and shrubs? Is there a certain season where I should start this process? These are questions we often hear from homeowners.  The answer is: yes and no! It is important to understand the type of tree or shrub you have before deciding when to prune. 

Some plants like roses, for example, can be trimmed any time of year as they don’t require cold weather dormancy. However, other plants such as fruit trees need cold weather in order to produce fruit.  

This article will help give insight into how to prune your plants in order to get the most out of them long term. Follow these guidelines for an ideal result!

What To Prune And When

Pruning is not complicated once you understand the three basic principles. These guidelines hold true whether you’re pruning trees or shrubs. So here are three top tips to pruning.

Choose the Right Tool

Always use clean, sharp tools. Select the right-size tool for the branch you will prune to avoid damage to the plant and the tool. Use a pruning saw on branches larger than 4 – 6cm in diameter. Pruners work best on the smallest branches. Use loppers on branches an inch or so in diameter. 

Choose the Right Time

There isn’t a single best time for pruning. Late winter is ideal for pruning many trees and shrubs because they are dormant, and it is easier to see what needs to be pruned. In addition, late-winter pruning promotes fast regrowth in spring. 

Some trees, such as maples, birches, and magnolias, bleed sap heavily if pruned in late winter. This causes little harm but can be avoided by pruning these trees after they are fully leafed out in late spring or early summer. Summer is the best time to remove dead branches when they stand out.

Prune spring-flowering trees and shrubs right after they finish flowering in spring. Trees and shrubs that bloom during summer and into autumn are best pruned in later winter or early spring as soon as their annual growth begins. 

Refrain from fall pruning because it stimulates new growth that could be killed by winter cold. Instead, prune anytime: suckers; water sprouts; branches that are dead, diseased, or damaged.

Make the Right Cuts

Holding the thinner, uppercutting blade nearer to the trunk or main stem, make a clean cut without tearing the bark. Avoid leaving a stub, which is unsightly and provides an entry point for pests and diseases. Instead, cut just outside the branch collar, the swelling where the branch begins.

Be safe when pruning:

  • Dress appropriately for pruning, wearing long pants, a long-sleeved shirt, gloves, safety glasses, and non-slip shoes.
  • A wide-brimmed hat keeps you protected from the sun, but make sure it doesn’t obscure your vision.
  • Keep tools sharp and clean. Store a sharp tool in a protective cover, if possible.
  • Carry pruning tools with the points facing down.
  • Choose a clear, still, dry day for pruning.
  • If you must prune from a ladder, tie it securely to the tree. Keep one hand on the ladder, and one hand on your pruning saw. Also, try and arrange for someone on the ground to help secure the ladder further.

Tools for pruning

The most important pruning tool is a good quality pair of secateurs. These should be the best you can afford. It’s a handy tip to wrap some brightly coloured plastic tape around the handle. This makes the secateurs stand out clearly, even if they are left half-buried in mulch on the side of a garden bed. Keep blades sharpened and joints oiled. Basic maintenance will help your tool last longer.

A good saw is another requisite. Ideally, select one with a narrow blade that can be manoeuvred into crowded parts of the plant.

Hedge clippers are necessary for trimming formal hedges. If this sounds like too much hard work, invest in a pair of electric or battery-powered shears. And don’t forget a strong pair of gloves – especially for rose pruning! (pictured)

How do roots do their work?

Some plants have a long, strong taproot with smaller lateral roots.  Others have a branched fibrous root system. 

Whatever form it takes, the root system absorbs water and dissolved nutrients from the soil through the root hairs (elongated cells just behind the root tip) and passes them to conducting tissue in the root, then on to the stem and other parts of the plant. 

Roots must respire (or breathe) to perform their task of absorbing and conducting efficiently, so a soil must be able to provide oxygen as well as water and nutrients.

Here are some common reasons for pruning:

  • To preserve the shape of the plant
  • To restrict the size of the plant (much better, though, to choose a plant that will grow to fit the space rather than being forced to prune constantly).
  • To encourage productive growth (e.g. flowering shoots on roses and fruiting wood in the orchard).
  • To remove deadwood
  • To remove old canes from the base (as in plants like May bushes and abelia).
  • To thin a canopy and allow air movement through branches.
  • To form plants into special shapes – topiarising, standardising or espalier.
  • To encourage colourful new growth (e.g. new red leaves on photinia).
  • To maintain a hedge or screen
  • To ‘stop’ upward growth on plants and encourage branching.
  • To reduce competition by thinning out crowded growth
  • To remove suckers from rootstocks on grafted plants. 

And of course, more reasons:

  • In early fall, pruning wounds close more slowly, and plants are more at risk of fungal diseases than other times of year. Therefore, the best time for major pruning for most trees is late winter to early spring because wounds close faster.
  • Pruning in late summer and early fall may also stimulate new growth, which has little time to harden before cold weather comes. The cold can harm this tender new growth, and the tree may need more pruning in spring to remove the damage.
  • If you want to prune in fall, wait until trees drop their leaves and are dormant—usually October or November. After leaf drop, you can see the tree’s structure and identify disease and insect problems more easily. Dormancy (especially late winter to early spring) is also a good time to prune evergreens because vigorous spring growth will hide pruning wounds.
  • If you want to transplant a small tree the next spring, late fall (October/November) is a good time for root pruning. This pruning technique stimulates new root growth at the cuts and helps a newly transplanted tree get established in its new location.
  • One exception to the no-fall-pruning advice is that you should remove dead, diseased, and damaged wood as soon as possible — for tree health and your safety. Take proper safety precautions at all times. Hire a professional arborist to remove big limbs, high branches, and any other tree job that you’re not prepared to do.

Proper Time to Prune Trees and Shrubs


An important aspect of pruning is knowing when to prune plants.  Proper timing helps to insure attractive, healthy, productive plants.  The proper time to prune trees and shrubs in the yard and garden are indicated below. 

Deciduous Shrubs

The proper time to prune deciduous shrubs is determined by the plant’s growth habit, bloom time, and health or condition. 

Spring-flowering shrubs, such as lilac and forsythia, bloom in spring on the previous season’s growth.  The plant’s health or condition determines the best time to prune spring-flowering shrubs. 

Neglected, overgrown spring-flowering shrubs often require extensive pruning to rejuvenate or renew the plants.  The best time to rejuvenate large, overgrown shrubs is late winter or early spring (March or early April).  

Heavy pruning in late winter or early spring will reduce or eliminate the flower display for 2 or 3 years. After that, however, rejuvenation pruning will restore the health of the shrubs. 

The best time to prune healthy, well-maintained spring-flowering shrubs is immediately after flowering.  (Healthy, well-maintained shrubs should require only light to moderate pruning.)  

Pruning immediately after flowering allows gardeners to enjoy the spring flower display and provides adequate time for the shrubs to initiate new flower buds for next season. 

Summer-flowering shrubs, such as potentilla and Japanese spirea, bloom in summer on the current year’s growth.  Prune summer-flowering shrubs in late winter or early spring.  The pruned shrubs will bloom in summer on the current season’s growth. 

Some deciduous shrubs don’t produce attractive flowers. However, these shrubs may possess colourful bark, fruit, or foliage.  Prune these shrubs in late winter or early spring before growth begins. 

Do not prune deciduous shrubs in late summer.  Pruning shrubs in August or early September may encourage a late flush of growth.  This new growth may not harden sufficiently before the arrival of cold weather and be susceptible to winter injury. 

Evergreen Shrubs

Prune evergreen shrubs, such as juniper and yew, in late March or early April before new growth begins.  Light pruning may also be done in mid-summer.  Avoid pruning evergreen shrubs in the fall.  Fall pruned evergreens are more susceptible to winter injury. 

Deciduous Trees

February through March is generally regarded as the best time to prune most deciduous trees.  The absence of foliage at this time of year gives the individual a clear view of the tree and allows appropriate branches to be selected and removed.  

Also, the walling-off or compartmentalisation of wounds occurs most rapidly just before the onset of growth in spring.  Oaks are an exception.  The winter months – December, January, and February – are the best time to prune oak trees. 

Deciduous trees can be pruned at other times of the year with little or no negative consequences.  However, if possible, avoid pruning deciduous trees in spring when the trees are leafing out and in fall when the trees are dropping their leaves. 

To reduce the risk of an oak wilt infection, do not prune oaks from March through October.  Oak wilt is a fungal disease that is lethal to many oaks.  

It can spread from infected trees to healthy trees by sap-feeding beetles (“picnic bugs”).  If an oak tree must be pruned in spring or summer (such as after a storm), apply latex house paint to the pruning cuts to avoid attracting sap-feeding beetles to the wounds. 

Fruit Trees

Late February to early April is the best time to prune fruit trees in Iowa. However, pruning should be completed before the fruit trees begin to break bud (leaf out) in early spring. 

Evergreen Trees

Evergreen trees, such as pine, spruce, and fir, require little pruning.  Dead, broken, and diseased branches can be removed at any time of year. However, late winter is the best time to remove unwanted lower branches on evergreen trees. 

Spruce and fir trees possess side or lateral buds on their newest (outermost) growth.  To promote denser growth, cut shoots back to just above a lateral bud or side branch in early spring. 

Growth on pine trees develops from terminal buds.  Pines do not produce side or lateral buds.  The growth of pines can be slowed by pinching or pruning off one-half to two-thirds of the elongated terminal buds (“candles”) in spring when the candles are approximately 2 to 3 inches long.  As new growth will not develop from these areas, do not prune branches back to older growth down the stem.

The Wrong Time To Trim Trees

Summer’s the wrong time to be trimming trees. From now through the beginning of winter is the worst possible time to remove healthy branches from a tree, especially one as magnificent as a river birch! 

Pruning during the growing season always stimulates new growth. But, during summer’s heat, having to produce that ill-timed new flush of growth greatly stresses a tree. Pruning in the fall is even worse as it prevents the tree from going into a natural dormancy.

The exception is heavily damaged, disease or dead wood. Those beat-up branches can — and should — be removed at any time. But the removal of healthy limbs should only be done in the middle of winter — the dormant period when the tree is essentially asleep — or in the spring when the tree has just begun actively growing again and new growth is forming naturally.

If you try to remove a 100-pound branch all in one piece, it will swing around, smack you upside the head and break your shoelaces. It will also tear the bark directly below that branch section all the way to the ground. That’s why large branches should always be removed in manageable sections — a foot or so at a time.

When you are ready to make the final cut closest to the tree, locate the branch collar — the round structure were the branch meets the tree. You want to leave that collar on the tree when you remove the last of the branch. Don’t cut flush to the trunk.

Nothing should be used to seal the cuts. Nature knows how to do that much better than we do.

Mushrooms On Wood Mulch

So, let’s see … you knew it was bad to use wood mulch, you kept using wood mulch anyway, something bad finally happened, and now you’re surprised?

The truth is that everyone who falls for wood mulch marketing will eventually get hit with a flush of mushrooms and/or other nuisance molds — some of which can cause severe (and expensive) cosmetic damage to homes and cars. 

Some people get hit with such problems the very first year they spread wood mulch, others get away with it for a decade or more. But sooner or later, the chickens — eh — fungal spores — will come home to roost.

For now, you can try spreading coffee grounds, lime or wood ash around the ‘shrooms to stop the spawning. But don’t yank them out. That spreads the spores.

Coffee grounds supply nitrogen, while lime and wood ash make the mulch more alkaline — both of which help inhibit fungal growth. But don’t use both — choose either grounds or wood ash/lime.

And of course, the long term answer is to switch to a mulch that isn’t attractive to rogue fungus such as compost, pine straw or pine fines.

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Wood Mulch = Worms (But Not The Good Kind)

These clever caterpillars (every pest with the word “worm” in its common name is actually a caterpillar of some kind) live in small nests — or “bags” — that look a lot like the pine cones that naturally appear on the plants they attack. And so the “worms” often escape detection — sometimes even while they’re eating the evergreen to the ground.

Bagworms — and similar pests such as tent caterpillars and fall webworms — often appear in response to stress, such as feeding with chemical fertilisers or — ahem — mulching with chipped-up pallets from China spray painted some God-awful colour.

The initial answer to any caterpillar problem is to spray Bt on the plant. Sold under brand names such as Dipel, Thuracide and Green Step, this organic pesticide made from a naturally occurring soil bacteria only affects caterpillars that eat the sprayed parts of the plant. Bt harms nothing else. The “worms” will stop eating immediately and die shortly afterwards.

In the long term, avoid using chemically-based plant foods and stop using mulches that stress your plants. Instead, switch to compost or pine straw. A healthy, happy plant rarely suffers these kinds of attacks.

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