If you’re thinking about pruning your trees and were wondering if there is a particular time of year to do it, then you’re in luck. This article is my complete guide for all of those people who need to know what time of year trees should be pruned.
The reason this is a complete guide and not a single line that says “trees should be pruned at X time of year” is simple. While, as a very general rule of thumb, late winter and early spring is the best time of year to prune your trees.
This is not always true and it is not true for every tree. There are many factors to play into when you prune a tree:
- Time of Year
- Type of Weather
- Species or Type of Tree
- Energy Cycle of Tree
- Pruning Affect During Different Annual Cycles
- Reasons for Your Decision to Prune
And a handful of other factors all go into determining whether or not it’s the right time to prune.
As a result, although “late winter, early spring” is a useful guideline, it is by no means a definitive answer. On the other hand, it is fairly simple, with just a little basic knowledge, to work out whether now is the right time, or not, to prune your trees.
Let me explain.
What’s the Best Time of Year to Prune Your Trees?
There are some exceptions, which I will go over later in the article, but for the vast majority of trees it is best to prune them while they are dormant. By doing so you will promote vigorous healthy growth in the spring and summer and minimize the possibility of damaging your tree.
As a general rule of thumb, the best time to prune the majority of trees is during the late winter and early spring.
When Exactly Is “Late Winter to Early Spring”?
It is impossible to give exact dates for this, or even to suggest anything more specific with regard to particular months or partial months. Why? Because the exact arrival of late winter and early spring changes from year to year, arrives at different times in different parts of the world, and can be defined in meteorological, astronomical & solar, and ecological terms. For example:
Definitions of Spring
Meteorological: Meteorologists define seasons by using average daily temperatures. Summer is defined first, by using the three continuous months with the highest average temperature.
Spring is then defined as the three months before summer.
This is why the end of winter and the beginning of spring varies around the world and why the timing of the seasons appears to be changing in response to climate change.
Astronomical & solar: The astronomical definition of the seasons is a cultural phenomenon and bears no relation to either the weather or the calendar. It is usually defined by a particular event such as the day on which the hours of daylight are equal to the hours of darkness. So, for example, in many cultures in the Northern Hemisphere, spring begins on the vernal equinox which falls between the 19th and 21st of March.
Ecological: From an ecological perspective there are several biological signs that indicate spring is here. These are events such as the blossoming of plants and the increase in the activities of animals. Unfortunately, by the time these events are in full swing, it is usually past the ideal time of year to prune your trees.
How Your Trees Decide It’s Spring
The process by which trees “decide” it is spring actually begins in the fall. As the number of daylight hours decrease and the temperatures drop, your trees will begin to lay down the groundwork for their winter period of dormancy.
Then, once your tree becomes fully dormant, it requires a certain number of “chill hours” before it will respond to environmental conditions and emerge from dormancy. Chill hours are counted as time that the tree is dormant and the ambient temperature is within a specific range.
Scientists are unsure of how a tree monitors the number of chill hours it has been dormant. What they do know is that a rise in temperatures alone is not enough to “wake” a tree that became dormant very late the previous year.
How To Use This Information
If you begin to experience sustained frigid temperatures early in the fall your tree will enter full dormancy and begin accumulating chill hours. In this case your tree is more likely to emerge from its dormant state at the first sign of warmer weather the next year.
On the other hand, if fall is mild and your tree does not become dormant until late in the season, or even early winter, then you can expect it not to respond to the first hint of warmth, and instead exit dormancy later in the year.
When is the Best Time to Prune Based on Species or Type of Tree
A different approach to figuring out the best time to prune is based more on the species or type of tree you are wanting to prune. Here we go through different types based on the following:
- Spring blooming trees
- Trees which ooze sap in the winter
- Evergreen trees in general
- Spruce or Fir trees
- Pine trees
- Soft growth evergreens
What Time of Year Should Spring Blooming Trees Be Pruned?
For spring flowering trees, the best time of year for pruning is a little different.
This is because the flower buds on trees such as star magnolia, and sand cherry develop on branches that grew last year. In this case you should wait until immediately after they bloom and deadhead them at the same time.
For those trees that bloom later in the year, you can stick to pruning when they are dormant. This will encourage new wood to form and maximize the trees potential for blooms.
What Time of Year Should Trees Which Ooze Sap in The Winter Be Pruned?
For trees such as oaks and maples you should avoid, at all costs, pruning while there is any possibility of freezing or frosts. This is because these trees will ooze sap when cut and if the sap then freezes there is the potential for damage to the trunk or limbs.
For this reason, it is best to wait until the summer arrives before pruning “winter sap oozers.”
What Time of Year Should Evergreen Trees Be Pruned?
For the most part, evergreens need little pruning. When they require a quick trim, it is usually as a result of the desire to maintain a particular shape, or to keep the tree away from structures, powerlines, and such. Before you begin to prune an evergreen, you need to know whether it is a species that produces its branches in whorls, as pine, spruce, and furs.
In the case of a tree that grows in a whorl pattern, you should only ever remove entire mature branches if they are dead, dying, dangerous, or diseased. To do otherwise will leave a gap where the branch is removed and new growth will not occur in a pattern that may fill the gap.
What Time of Year Should Spruce or Fir Trees Be Pruned?
Prune spruce and fir trees in early spring, before the formation of new buds for the following years growth. If you cut a shoot back to a lateral bud before growth starts, growth will continue from that bud for the rest of the year.
Alternatively, wait until mid-May to early June and prune half of the new growth, once it has extended. This will keep the tree from growing beyond the dimensions you wish and, at the same time, encourage greater density.
What Time of Year Should Pine Trees Be Pruned?
Most pines are best pruned in mid-June before the needles start to unfold. At this time, the new growth looks like candles. *It should be noted that the date of pruning will depend on the year and could be different each year.
When these terminal shoots are soft, they may be cut back to one-half to one-third of their length. This will control the length of subsequent growth for that season. New terminal buds will form at the cut ends by the end of the growing season and growth the following year will spread out from those points. (see below).
What Time Of Year Should Soft Growth Evergreens Such As Juniper Trees Be Pruned?
Evergreens with soft growth such as Junipers, may be pruned by clipping back new growth preferably in early spring to mid-June. Clipping back the most vigorous branches once or twice a season will keep the plant dense without destroying the natural appearance.
What If You’re Not Sure About Your Tree?
If you are unsure about what time of year to prune a particular tree, and you are unable to find species-specific information, there is a way of making a reasonable estimation.
Think of your tree as having an energy cycle.
During winter your tree is dormant and the majority of the tree’s energy is stored in the roots. By pruning at this time of year you will remove a piece of the trees limited “above-ground energy capture” system. The tree will respond by attempting to restore its capacity to capture the sun’s energy, and it does this by producing new growth.
During spring, your tree will begin to focus its energy on new growth. Pruning at this time of the year removes those buds, and reduces or puts an end entirely, to flowering.
Summer sees your tree putting its energy into fruits and other new growth. Pruning at this time of the year will remove some of the competition for energy and cause your tree to focus on the remaining fruits. This will, in turn, result in bigger, healthier fruits.
Fall sees your tree dropping its leaves and preparing to send all excess energy down into the roots, ready for winter. Pruning at this time of the year will take away sources of energy that your tree will need to redirect to its roots.
If you are unsure whether or not it is the right time to prune your tree then take a look at your tree’s current stage in the energy cycle. Think about where your tree is currently focussing its energy and how much valuable energy you will remove by pruning right now.
How Pruning Affects Plants At Different Stages Of Their Annual Cycle
The impact that pruning will have on your trees will be determined by the time of year during which you choose to prune. If you want to ensure, or avoid, a particular result in response to your pruning, you’ll need to be aware of what will happen when you prune your trees at different times of the annual cycles.
Pruning during dormancy
- This will result in vigorous, and healthy growth once the tree emerges from its dormant period.
- For the majority of trees, you will see lush, dense growth in the canopy.
- Some trees may respond by sending up multiple, unsightly water sprouts.
Pruning after buds form
- Good for invasive plants because it will, depending on how vigorously you prune, decrease or eliminate flowering.
- Bad for ornamentals as you will severely restrict the trees ability to bloom.
Pruning before buds form
- For trees that set buds on the previous year’s growth, avoid pruning before buds form or you risk severely reducing the number of flowers this year.
Pruning after flowering
- Good for fruit trees because it concentrates the trees energy into the remaining fruit.
Pruning after fruiting
- While you should not attempt any drastic pruning at this stage in a fruit trees life cycle, the removal of some limbs shouldn’t encourage any new growth before the tree becomes dormant.
- If you wait until after fruiting and after the fruits on the tree have set seed you increase the risk of disease. This is because the tree is “exhausted” from its cycle of fruit production and will have less energy with which to heal from wounds.
What Are Your Reasons For Pruning?
The first step to determining whether or not now is a good time to get out your pruning tools is to think about why it is you are planning to prune.
Dead, Dying, Diseased, Or Damaged Limbs
If you are pruning to address one of the four D’s – Dead, Dying, Diseased, or Damaged limbs then, generally speaking, the best time to do your trimming is now. No matter what time of year it may be. The reason for this is simple.
Dead, dying, diseased or damaged limbs leave a tree vulnerable to further damage and disease. If you leave the pruning of a “4D” branch or limb until the “right” time of year then you are at greater risk of negatively affecting the health of your tree than you are by pruning at the wrong time of year.
So, to recap, if you are pruning your tree to address a dead, dying, diseased, or damaged limb, it is safe to do so as soon as you notice the issue, no matter what the correct time of year for pruning the tree.
If You Are Pruning To Reduce Shade Or Wind Resistance
There are occasions when your tree, or trees may have grown either larger than you had originally thought, or in a different way. As a result, you may want to either thin out the canopy to reduce the potential for wind damage or trim the canopy back to allow more light to the surrounding area.
If this is the case then you will want to establish which branches you wish to cut back while the tree is dormant. This will not only make it easier to establish which limbs to prune but it will also allow you to see how pruning will affect the overall shape of your tree.
Unless your tree is one of those which should not be pruned in late winter or early spring, then this is the best time to prune for a reduction in shade or wind resistance.
If You Are Pruning To Provide Clearance, To Fit A Space, Or Prevent Infringement
If you have to prune a tree to prevent infringing on a neighbors garden or to prevent it becoming an issue for power lines, it is still best to do this when the tree is dormant in late winter or early spring.
To prevent a situation where you find that your tree requires clearance pruning in the summer, make a habit of inspecting your trees during the winter and cutting back any areas that may cause a problem later in the year.
When You Are Pruning to Manage the Aesthetics of a Tree
Sometimes we just want to prune a tree in order to create a size or shape we find pleasing. If aesthetics are your motivation for pruning then the late winter and early spring window is the best time to prune. That is unless you have a tree which has an ideal pruning window outside of this time period.
If You Plan To Prune To Manage Your Tree’s Fruit Production
If you are pruning your tree to manage fruit production then what time of year your trees should be pruned is quite different.
While the advice for the 4 D’s remains the same, if you are pruning to promote better quality fruit on your tree then the time to prune is when the is in flower. Pruning branches with flowers will cause the tree to divert its limited energies into the remaining flowers, which will become fruit.
Repairing Storm Damage
If you are looking at the garden and your trees have post storm damage then there are two phases to your pruning plan:
- Begin by identifying any limbs which are damaged or may pose a danger and prune these immediately.
- Then, wait until the correct pruning window for your tree before carrying out any other work. If you repair immediate damage and then carry on and remove further limbs at the same time, in an attempt to reshape your tree, you may well over prune and cause your tree additional stress. It is always better to wait and carry out any non-vital pruning at the “correct” time.
Tree Pruning Tips
No matter what type of tree you have, or what time of year you should prune it, there are some basic do’s and don’ts.
- Do not prune on a damp day. Each wound you leave after pruning, is a place where pests or disease can invade your tree. The higher the humidity level, the more chance you have of your tree contracting an infection. Instead, try to wait until a dryer day before breaking out the pruning saw.
- Resist the urge to begin pruning in the fall when you are cleaning up the leaves and getting the rest of the garden ready for winter. During fall your trees are slowly withdrawing the majority of their energy from their limbs to their roots. When you prune back healthy limbs in the fall you will be depriving your tree of some valuable energy stores.
- Likewise, bite back the urge to start pruning too early. If there is still snow on the ground, the earth is frozen, or if it just plain and simple feels like winter, do not start pruning. This is because if the temperature drops below freezing after you have pruned, the incisions can dry out and this prevents your tree being able to carry out the correct steps to repair the damage and remain healthy.
- When you do begin pruning, be sure to take out any dead, dying, diseased, or damaged branches first. The removal of these limbs may alter your pruning plan for the rest of your tree so by taking them out first you minimize the chance of over-pruning or just of ending up with an ugly, oddly pruned tree.
- Even though the ideal pruning time for some evergreen trees may not be the general late winter and early spring window, you can remove any unwanted lower branches at this time of the year.
- Remember to make your cuts parallel and close to the trunk or the spot where one branch meets another.
- If you are cutting off a dead branch, do not cut into any collar that has formed around the base of the limb. This will avoid inadvertently cutting into the living tree tissue.
- Never remove more than 25% of a trees limbs in a single year. To do so is to greatly increase the chances of your tree dying.
- No matter what time of year you are pruning be sure to check your pruning equipment is clean, dry, and sharp. This will minimize the risk of causing damage to your tree, or of introducing infection into the wound.
Conclusion
In the same way that there are countless species of trees, each with their own particular quirks and needs, there are a multitude of answers to the question “What time of the year should you prune your trees?”
However.
There are some general guidelines that will help you establish whether or not the time is right to prune any particular tree.
Why you are pruning your tree should inform, to some degree, when you prune. If you are pruning to remove dead, dying, deceased, or dangerous branches you should do so as soon as you spot them. When you are pruning for any other reason the following guidelines apply.
Generally speaking, late winter and early spring is the best time of year to prune most trees. At this stage the majority of trees are beginning to emerge from their dormant period. This means they will have the energy to heal effectively from the wound caused by pruning, as well as to go on to produce plenty of healthy, lush growth.
For trees that produce a large amount of sap in the winter, such as maples, it is best to wait until the early summer when the pruning will not result in copious amounts of sap.
Evergreen require little in the way of pruning but when they do, spruce and fir can be pruned in early spring, although late May and early June are best for controlling a spruce or fir trees size. Pines meanwhile benefit most from a mid-June prune, before the new needles have had a chance to unfurl.
Whatever species of tree you are pruning, be sure to employ good timing and proper pruning techniques and your tree should continue to give you pleasure for many years to come.
