Arborvitae make for popular and attractive landscaping additions. These cedar relatives are commonly used both as hedge components and as stand-alone features. Either way, your arborvitae is getting too tall, and you are wondering if you can top it and how to go about that process. Well, in this post, we answer your question using up-to-date research and techniques.
Yes, if done properly, topping arborvitae is possible. While this process forever changes the shape of arborvitae, healthy plants are likely to survive. Take note; most arborists agree that routinely pruning arborvitae is preferable to topping. However, to properly top arborvitae, follow these steps:
- Wait until late winter or early spring
- Carefully choose your top location
- Using a sharp saw, cut off the arborvitae's top
- Monitor after topping
Read the rest of this post for details on the pros and cons of topping your arborvitae. We also go over detailed step-by-step directions on how to accomplish this task. To conclude, we introduce how to prune arborvitae and answer a related question.
What happens if you top arborvitae?
The most common growth pattern for arborvitae is one main trunk and several smaller leader trunks. These all point up. Topping arborvitae means cutting all of these vertical elements off at a uniform height.
If you do top an arborvitae's main trunk, it will grow no new additional leaders. This creates a boxy shape and means that the classic tall pyramidal shape of the arborvitae will never return. Further, topping arborvitae can lead to a bald or brown patch on the top of the plant.
For this reason, most gardeners recommend pruning an arborvitae if the size or the height is a concern. Keeping your arborvitae at a certain size or height using just pruning and no topping involves nothing more than yearly care.
How to Top An Arborvitae
While topping an arborvitae is not the preferred method for changing the stature of these conifers, it is sometimes the only feasible option. In that case, it is important to follow these steps to ensure that your tree or shrub will survive this rather significant loss of mass.
Wait Until Late Winter or Early Spring
Even though arborvitaes do not lose their leaves or needles during the winter, they still undergo metabolic changes. Arborvitae and other conifers go dormant during the cold winter months, as discussed in this article from Cashman Nursery & Landscaping.
As soon as spring returns, the plant and roots start to grow again quickly. In fact, according to Northern Woodlands, the roots even start to function before the above-ground parts of the plant. By topping in late winter, you maximize the growing time your arborvitae has to recover from topping.
If you topped in late summer instead, your arborvitae would have to both recover from the topping damage and enter full dormancy with far fewer days of growth. This shorter time span means fewer hours of sunlight to build up the energy and nutrients required for overwintering.
Choose your Top Location
It might seem obvious that it is important to thoughtfully choose the desired height for topping. However, it is important to think this step through carefully. First of all, the arborvitae will likely not get taller once you top it.
While keeping the height consistent is the goal, this lack of additional growth also means the brown inner branches are exposed, a condition that may never heal. So take into account where you can see this scar from and adjust the height accordingly.
Further, you may be topping more than one arborvitae, such as in a hedge. In this case, it is efficient to have a stick or board cut the desired length so that you can easily match the height of all the trees in the entire hedge.
Use a Sharp Clean Saw
For best results, whenever you are performing pruning or topping, always use sharp, clean implements. Dirty cutting tools can introduce bacteria and other contaminants to the wound you are creating. In the same way, dull tools create a more jagged cut which is more difficult for the plant to heal.
For arborvitae topping, the tool of choice is usually a handheld pruning saw. These tools are appropriate for medium-sized cuts. For very large trunks, you might want to use a chainsaw. For very small or young arborvitae you want to cut, pruning shears may be appropriate.
To clean your saw, simply wash it in soap and water, rinse, apply rubbing alcohol, and allow it to dry. Often it is difficult to sharpen saws, but it is not expensive to replace a dull blade. Alternatively, some specialty shops will sharpen saws to a level even better than new ones.
Monitor After Topping
Since arborvitaes are hardy, healthy trees, they often recover from topping without any additional care. However, sometimes the topping creates too much stress on the plant. When this is the case, you might notice the remaining green turning brown, wilting, or new or serious pest infestations.
Provide your tree with what it needs. This might be additional fertilizer or compost, it might be extra water during the hottest summer months, or it might be pesticides. Take the time to research the condition and fix it accordingly. Your local extension office or nursery are both good resources.
If you are worried about your arborvitae healing. It might be worth it to apply tree wound care to the topped trunk. This product provides an artificial barrier to stop bacteria, fungus, and other contaminants from getting into your tree.
Pruning an Arborvitae
Once again, the most aesthetically pleasing and healthiest way to keep an arborvitae short is to prune routinely. Usually, this is performed in late spring to early summer. The rest of this sub-section provides some quick tips on arborvitae pruning.
The most important tip is to avoid cutting off more than 1-foot of the branch at any time. The reason for this advice is that any more and you may start cutting into the brown part of the branch instead of the green. The difference is the green will keep growing after being cut, but the brown will not. You can also lightly scratch a branch to determine the inner color.
It is best to prune during spring or early summer because this gives your tree or shrub plenty of time to regrow during the rest of the growing season. As for topping, it is best to use shears that are as sharp and clean as possible.
With regular pruning, you can limit the height and spread growth of arborvitae to whatever limitations you want. The biggest advantage of this is the whole outside of the plant will be green and vibrant, unlike the brown of a topped tree.
How do you stop evergreens from growing taller?
Unfortunately, pruning or cutting your evergreen tree is the only reliable way to keep your tree from growing taller. While it is possible to stunt growth by starving the tree for nutrients and water, this will also produce an unhealthy ugly looking tree.
It is possible to slow your evergreen from getting taller by applying growth inhibitors to recently pruned limbs. However, this still requires pruning the limbs and will only slow the upwards growth of your tree; it will not stop it.
Hire an Expert
Pruning and topping trees can be both dangerous and difficult. While this article provides most of the information you need to top your arborvitae, there are always additional tricks of the trade. Consider hiring a local arborist expert to ensure a quality finished product that is a positive addition to your yard.
Garden Tabs has a wide selection of reading on many gardening topics. Consider these related articles: 7 Best Arborvitae Fertilizers, 17 Best Privacy Bushes And Shrubs, and 19 Fast Growing Shrubs For Screening Purposes.
In this article, we answered the question of whether or not you can top an arborvitae. To follow this, we provided step-by-step instructions on how to accomplish this task. We also include advice on how to prune arborvitae and the answer to a related question. Good luck!