Summer’s The Wrong Time To Be Trimming Trees

Rich in Brighton asked us, I help a neighbour lady who has a large River Birch that’s very close to her front door. She wants to remove some branches that are beginning to have an impact on her access. They are not small branches. When is a good time to remove them, and how should we seal the cuts to prevent the disease from entering the tree?

You are very wise to ask before cutting, Rich — 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. During summer’s heat, having to produce that ill-timed new flush of growth greatly stresses a tree.

Pruning in the Autumn 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 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.

Warning: If you try to remove a 50 kg 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 where 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.

When Should You Not Trim Trees?

Cut larger limbs while trees and shrubs are dormant.

When is the best time of year to trim tree limbs and cut back shrubs?

The best time to prune or trim trees and shrubs is during the late winter while they’re dormant. Pruning during the dormant season is ideal because:

• The wounds heal faster, keeping the plant strong.
• There is less risk of disease or pest infestation.
• There is less sap flowing. Bleeding sap doesn’t really hurt the tree, but it’s messy and can attract pests.
• It’s easier to see what you’re doing while the leaves are gone.

Pruning Guidelines:

1. Conifers: Prune in late winter while fully dormant.
2. Non Blooming Trees and Shrubs: Prune in late winter while fully dormant.
3. Summer-blooming Trees and Shrubs: Prune in late winter.
4. Spring-blooming Trees and Shrubs: Wait until immediately after they bloom. They are the exception to the rule, but you still should prune them as early as you can.

 What happens if you prune a tree at the wrong time?

Ask any tree service professional what they are asked about most, and they’ll tell you it has to do with pruning, the periodic cutting back of perennial woody shrubs and trees.

Many homeowners understand why these plants need to be pruned periodically. They’ve no doubt heard at one time or another that properly pruned plants are generally healthier, live longer, and look better.

While there are many benefits of properly pruned trees and shrubs, most people have no idea what ‘properly pruned’ actually means. Truth is, pruning is both an art and a science; it requires the pruner to get up close and personal with the plant, while also taking a few steps back to see how each cut has impacted the overall look of the plant and the landscape.

What makes matters worse is that there is no overarching rule to follow. Different types of plants, trees, and shrubs require different pruning techniques. The bottom line: know your plants, or hire someone who does.

Here are a few examples of how DIY pruning can go wrong and what you can do to avoid these all-to-common blunders.

Mistake #1 – Pruning at the wrong time of year.

Although there are a few instances when pruning can (and should) be done at any time (for example when removing dead, damaged, or overlapping branches), most plants benefit from pruning at specific times of the year.

Prune plants that flower during the summer, such as Rose of Sharon, barberry, and gardenia, while they are still dormant in late winter or early spring. Without foliage, the woody structure of the plant is more visible making it easier to determine where cuts should be made. The rush of spring-induced growth will also allow the plant to heal itself faster. Arborvitae, cedar, hemlock, and juniper trees should also be pruned during this time.

Prune woody shrubs that flower during the spring, such as azalea, lilac, forsythia, and rhododendron, immediately after their blossoms fade in late spring/early summer. Doing so will increase the plants bloom in the following year. Trees such as cherry, ornamental pear, pine, and spruce should also be pruned back in early summer.

Most importantly, tree service professionals recommend that homeowners avoid pruning back trees that produce a heavy sap flow during the spring until after the leaves have fully developed. Otherwise, the cuts may put too much stress on the plant and make it make it more susceptible to pests, disease, or drought conditions. This includes many of the most abundant New England tree species such as birch, elm, and maple.

When Is The Best Time To Prune Trees?

Sometime between the changing leaves in fall and flower blooms in spring, your trees need a trim. Anytime between late autumn and early spring is best for tree trimming or pruning.

Talk to your local arborist about pruning before spring blooms emerge. Typically a tree’s pruning cycle is 3 to 5 years, but type, size and health play a role in the cycle that will work best for your tree. 

Trimming Large Branches In The Summer?

In general, pruning a tree when it is dormant is recommended if there are large branches to remove; that is, pruning between the time the leaves fall from the tree in the fall and the time the buds swell in the spring. However, pruning for safety reasons or minor pruning may also be done in the summer. In fact, some shrubs and spring flowering trees are best pruned immediately following flowering in the spring.

As I said, pruning for safety reasons should be done now! The safety of your children is more important than the tree. If, for safety reasons, you must do the pruning in the summer, do it. If you can delay, delay as long as the construction is progressing — the later in the summer that you prune, the less impact you have on the tree but, if it must be done today, do it today. Prune as much as is needed to ensure the safety of your children. If more pruning is needed later, then delay that until winter when the tree is dormant.

It sounds like the tree is relatively healthy, so the pruning should not be extremely damaging to the tree. However, you can’t prune without having an influence on the tree, and some of that influence is negative. Regarding the use of pruning paints – we do not recommend the pruning paints. However, we do recommend that you prune properly. If proper pruning cuts are made, the effect on the tree is minimized. Information on proper pruning is available from your local Cooperative Extension Service Office.

Can You Kill A Plant From Over Pruning?

Although over pruned trees and shrubs don’t usually die if some part of the canopy remains, the damage from over pruning can be extensive. Over pruning reduces the foliage that’s available for making food for the rest of the plant and can allow pests and diseases access to the tree, if cuts are made incorrectly. Plants may sprout excessively in response to so much canopy loss, both to protect the bark of the plant from sunscald and to increase food production. Over time, continued over pruning may lead to branches that are too weak to tolerate wind or ice loads, or the plant may simply exhaust itself trying to replenish its canopy. The plant may become extremely weak, allowing a variety of pathogens and insects to invade. So, although pruning may not kill your plant directly, over pruned trees and shrubs can die as a long term result of the associated stress.

How To Repair Over Pruning

Unfortunately, the damage from over pruning can’t be fixed, but you can help your tree overcome the many difficult days ahead. Provide proper fertilization and water to help your plant along; its diminished capacity for photosynthesis means that it’s more important than ever that your plant has all the building blocks it needs readily available for food production. Wound dressing is rarely recommended, with only a few exceptions, such as when oak wilt disease is common in the area. In this case, wound dressing can prevent the penetration of vectoring beetles into healing tissues. Otherwise, leave wounds open. It is now believed that dressing wounds slows the natural healing process in bushes and trees.

Time is the only real cure for over pruning, so when you decide to prune, do so carefully. Remove no more than one-third of the canopy at a time, and resist the urge to top your trees. Topping is a practice that’s very bad for plants and may lead to brittle canopies.

How do you prune a dying tree?

in order to avoid insect and fungal problems, it is important to regularly prune out wood that is dead. Diseases and insects are attracted to dead branches on trees and shrubs, and once they have been established there, they will spread into live and healthy wood. If allowed to remain, these pests will weaken the tree, allowing other insects and disease to become established. Eventually the tree will die of one or many of these causes.

It is important to use tools that are sharp, as dull tools will make an uneven cut which will lead to tissue at the site of the cut dying, leaving it open to infection.

It is also important to use tools that are sterilized, since fungi can very quickly colonize dead wood, even though it may not appear to be infected, it is very likely to be. Fungi are easily spread by contact, so dipping your tools in a sterilizing solution between every cut will prevent the possible spread of disease. We recommend a mixture of one part Bleach or Javex to nine parts water.

When pruning out dead wood as well as diseased wood, it is important that the cut be made four to six inches into live and healthy looking wood. This will ensure that all dead and dying wood is removed. If the cut is made too close to the infected wood, or dying wood, then the problem will likely recur. To find the point where the dead wood ends and the live wood begins; move back along the branch making nicks in the bark until the wood is green. If the bark has no green inside, then the wood is dead.

When pruning a branch or twig, it is important to cut correctly. In the case of pruning smaller twigs and branches, always move back along the wood to the nearest bud or branch. The cut should be made not more than ¼ inch from the bud, as cuts too far away cause dieback. Anything too close will damage the bud, or allow disease spores to enter it. Slant the cut away from the bud or branch, to prevent water from accumulating on the bud.

How Do You Protect A Tree After Cutting A Limb?

In most cases, it is actually better to leave a cut tree limb alone and let the tree seal itself, which it will do over the course of one or two years. In certain circumstances, however, a tree might need a little help in order to ensure its health. If, for example, a limb is cut during spring or summer, when the tree may be more susceptible to insects and disease than during fall or winter, then sealing the stub left from the removed limb will protect it from harm. Also, a tree cannot heal itself if weather conditions are increasingly dry, such as a drought, and sealing the cut area will help the tree retain moisture.

Remove all jagged edges where the tree limb was cut. Saw a thin section of 1/2 inch from the limb stub in order to make the surface smooth and flat. The remaining area where the limb once was should be about 1 to 2 inches outward from the trunk. Wear safety glasses and gloves to protect them from the pruning saw’s blade and from debris.

Dust debris from the limb stub. Doing so cleans the stub and will allow liquid pruning sealer to coat it properly. If the dust were left on, then the sealer might brush off when the dust is loosened.

Dip a paintbrush in the container of liquid pruning sealer, and use the paintbrush to coat the limb stub with the sealer. Brush the sealer back and forth over the stub and around its edges to ensure it covers the wood fully.

Allow the sealer to dry for one hour, and then check the stub to ensure it is completely covered with the sealer. If you find a spot that isn’t coated, repaint the section to cover it with sealer.