Actually, the correct term is tree pruning. Years ago when I first started in the industry, I specifically remember the phrase “prune the word trim from your vocabulary”. However, for the sake of simplicity, and because it’s an important search term, we will continue calling it tree trimming for the rest of this page…
When Should a Tree Be Trimmed?
I am getting a lot of questions about whether or not a tree should be trimmed. I am one of those honest business owners who will tell you if tree trimming is necessary or not, and if it is not I will tell you not to have it done.Over pruning can do more harm than good by stripping the tree of too many leaves necessary for photosynthesis, and therefore starving the tree.
The main reasons trees are trimmed in an urban environment are:
- Tree Safety
- Tree Health
Other reasons include:
Structural pruning on younger trees is often necessary to guide the trees to healthy future growth, such as training a single leader with no co-dominant stems or crossing branches. Pollarding is a highly specialized form of tree trimming that generally is used to control height and for uniformity.
Please note that general pruning to ISA pruning standards includes:
- Class One Pruning – the finest class, which most of my customers want
- Class Two Pruning
- Class Three Pruning – the least of the three classes; the minimum level recommended
Check the International Society of Arboriculture (ISA) web site for detailed descriptions at www.isa-arbor.com.
Safety Tree Trimming
Safety tree trimming comes into play when there are limbs that threaten target zones such as structures, cars or people in general. Sometimes limbs are overextended (ie. too long, often with too much end weight), crotches are weak with included bark, and/or the trees are generally very thick and heavy throughout. When some or all of these factors are present, often a tree may be hazardous and action must be taken. In most of these instances, thinning is generally an acceptable remedy, sometimes in conjunction with cable installation in the case of overextended limbs or split crotches. Some trees may be hazardous for other reasons such as rot or root damage. Sometimes limb removal or even tree removal is the only option. This is where hiring a seasoned certified arborist is crucial.
Health Tree Trimming
Health tree trimming mainly involves removing dead wood from the tree so the branch collar can close up and the tree can begin the healing process, minimizing rot in the healthy wood. This is also important because it minimizes carpenter ants which live in the dead branches on the tree and can get into your house.
Tree thinning is also often important for the health of the tree because it minimizes general splitting and the consequential wounding it can create; in particular splitting from ice storms and general thunder storms with high winds and rain. If you have been in Central Texas for any amount of time I am sure that you are familiar with both.
Other health pruning aspects include crossing branches and diseased/broken limbs. This would include mistletoe removal and removal of limbs that have been rubbing against each other and causing wounds from the constant agitation. These agitating limbs, especially on live oaks and red oaks are a cause for concern because they are avenues for infection. Knowing tree species is critical when prioritizing work, and again a seasoned certified arborist is the only way to go. If a tree is miss-identified, often it is improperly pruned.
Aesthetic Tree Trimming
An example of aesthetic tree trimming would be pruning the native ashe junipers (cedar trees) to remove dead wood. These trees have a different physiology from hardwoods and do not close their wounds when dead wood is removed. Rather, they have tannins in the wood that make the wood extremely rot resistant instead. Subsequently, dead wood removal is considered aesthetic pruning on these trees. Bald cypress would also fit this category.
Ball Moss Removal
Ball moss removal in most instances is also aesthetic pruning. Ball moss is not parasitic, but is an aerophyte (air feeder) like a bromeliad. Most of the ball moss comes out with dead wood removal. In Austin, most of the time ball moss infestations are light and standard pruning removes most of it. Generally, pruning the rest of the ball moss from the healthy limbs constitutes aesthetic pruning, because it does not negatively affect the tree. However, extremely heavy infestations (generally found in other, more humid parts of Texas) can be detrimental because the ball moss can grow to the ends of the limbs and choke out the leaves. Sometimes heavy infestations in central Texas can lead to additional limb failure during ice storms, for example due to extra weight on the branches, especially if the tree is very dense.
View pruning is a term that upsets many arborists (not my favorite subject either). It is not ideal and in most cases has a detrimental effect on the overall health of the tree. It is controversial. Generally, view pruning involves reducing the height of the tree to see over the top, or in the case of extremely tall trees, generally involves opening up the tree through the center to see through it.
View pruning is extremely difficult to bid, and in most cases tree care companies generally end up having to bid it on an hourly basis because it is very time consuming, generally is on slopes where brush cleanup is a nightmare, and as the trees in the front are pruned, other trees behind them are opened up and need pruning also. Most reputable tree care companies generally offer it as one of their services out of necessity. It can be done with minimum impact to the tree, but generally needs to be done yearly and in the winter for minimum impact. Aspects of height reduction such as drop-crotching and yearly pollarding are often used. I will do view pruning where it can be done with minimum impact to the trees, and do understand how a good view can impact the value of a property.
Crepe Myrtle Pruning
Not many trees grow in this soil and climate, but crepe myrtles are the exception and thrive here. There are two way to prune them. The first and best way is to thin them, remove the dead wood and crossing branches, and treat them like a small tree. This is the way most (arguably all) horticulturists would like to see it done. The second way, often referred to as crepe murder, is called pollarding.
Pollarding is when the tops of the crepe myrtles are reduced so that the plant grows to the same height every year. It is usually done for uniformity, to keep the plants all the same size and height such as medians. It is also done when growing space is restricted such as plants too close to structures or to large shade trees. Once it is started, it needs to be done yearly and in the winter, preferably January through mid February, but most years we can get away with some March pruning also.
Pollarding can be done to several species of trees also. These include sycamores, white or fruitless mulberries, fig trees. Of course shrubs are pollarded across the board (hedges). Other tree species can also be pollarded, but here in the US these are the main types.
As you can see there are many factors. I did not even talk about fruit trees. My advice to you is to call me out if you need tree trimming, or think you do. I will assess your trees, advise you on the suggested actions and give you a bid for any needed services.
Again, your trees are too valuable and you need the advice of a well-trained, educated certified arborist. Additionally, hiring a professional such as me, with a degree in the field such as a forestry or horticulture who has the educational foundation and knowledge is even more to the benefit of you and your trees. Please call me for an estimate/walk through. I’m happy to come out and take a look!