Pruning: A Quick Guide
Any beautiful landscape can be broken down into different layers of color, texture, form, and line that morph throughout each season to captivate and calm the soul that lives in its midst. When a professional landscape designer is establishing the foundation of those four elements, their plant selection plays a vital role in how those elements interact as the landscape matures.
Hardscapes do not grow, and everyone knows that grass must be mowed on a regular basis to remain healthy and to keep a clean look. However, the larger plants of the landscape grow more slowly. They are therefore less likely to receive the frequent and proper attention that they also need in order to remain healthy and maintain their intended aesthetic role in the original vision of the landscape. Because these plants don’t demand your attention as frequently as your lawn does, simply remembering the importance of pruning your ornamental plants is the first step. But how should you prune? When should you prune? Should you simply take a pair of hedge trimmers to every plant on the property? Is it OK to prune any plant at any time of the year that you’d like?
In this article, I want to help you, the homeowner, understand how to prune properly, and how to properly time the pruning of many different plants in the landscape. Let’s start with timing.
Cut in the Cold
As a general rule, late winter is the best time for pruning most plants. Just remember the slogan: “Cut in the Cold.” For North Carolina, February is a great month for this work.
What’s so magical about the winter? There are several factors at play that make the winter months perfect for pruning. First of all, plants are in a state of dormancy during the cold of winter. During dormancy, deciduous plants have dropped their leaves, exposing their branch structure to allow easier visibility when deciding what to remove. Without the added weight of those leaves, the branches will also be easier to untangle from the plant when removing, causing less damage to the remaining stems.
Another factor at play during the winter is that both deciduous plants and evergreens have significantly less fluid flowing through their systems. This results in less stress on the plant when wounded, and less sap being exposed because of those wounds. Sap attracts the undesirable attention of boring insects (“digging” insects, not “un-exciting” insects), which would cause more wounds and bring in disease spores from other plants on their bodies.
Even if the sap did flow during the winter, there’s another advantage at play during these cold months. Plant diseases and the insects that carry them are also significantly less active. All these factors come together to create the best environment to minimize damage, heal wounds and avoid dangerous diseases and pests.
WHAT TO WATCH OUT FOR WHEN PRUNING IN WINTER
Despite all of these advantages, there are a few plants for which it is best to avoid winter pruning, mainly for ornamental reasons. Plants that are the first to bloom in the spring have formed the buds for those flowers during the fall. If you prune them during the winter, You will be cutting off those buds and losing those flowers. This does not harm the plant, but it may affect your desired outcome for the following spring, so you should be aware of this before pruning. These plants include cherry trees (Prunus sp.), red buds (Cercis sp.), forsythia (Forsythia sp.), dogwoods (Cornus sp.), azaleas (Rhododendron sp.), and camellias (Camellia sp.).
OK. Winter is over. What about pruning needs during the rest of the year?
Any gardener will be able to find pruning needs in the landscape during the other three seasons. Knowing what plants should be pruned at what times is typically determined by the plants' flowering and growth habits. I recommend consulting pruning calendars made by trustworthy green industry professionals who have already asked all the necessary questions for each plant to determine the right timing. Below is a simple pruning calendar that we use here at Canopy. It displays proper pruning months for 25 common ornamental landscape plants in North Carolina.
In case you don’t find what you’re looking for on this calendar, I have included a few other resources that we have found useful thanks to the help of our friends at NC State University. The Following three resources are all pruning calendars that were published by Virginia Cooperative Extension: a Deciduous Tree Pruning Calendar, a Shrub Pruning Calendar, and an Evergreen pruning Calendar.
The majority of Virginia and North Carolina share the same Climate Zones, so the plant selection will be largely the same. (The Climate Zones of Raleigh and Charlotte in particular are the same as Virginia's majority climate-zones.) For Further reference, North Carolina State University also has a helpful general pruning calendar guide that is worth reviewing before pruning.
Before you do anything, remember that you can always cut more off later, but you can never undo a cut. Every cut is final, so take your time. If you don’t feel confident about a certain cut, leave it for the moment and come back to it later with fresh eyes. Also remember that the plant needs enough foliage to fuel its recovery from whatever cuts you make. Never remove more than one third of the plant’s existing structure. Obviously, there are exceptions, but please be conservative unless your goal is a rejuvenative hard cut-back. Always start the pruning on any plant by addressing the “3-D’s” first: Dead, Diseased, and Damaged plant material. Any time you prune dead or diseased plant material, it’s a good idea to clean your pruning tools with rubbing alcohol or Lysol before moving to other plants. This will help prevent the spread of any diseases that are present in the wood you’ve cut.
Think about the future!
Anytime you cut a branch, the bud that is next on the stem closest to the cut will be the bud that receives most of the energy that was originally ear-marked for the entire branch that was removed. That bud will grow the fastest and therefore be the main initiator of how that portion of the plant will look in the coming growing seasons. When cutting a stem, think about where that last bud is located and what direction it is facing. For example, if you want to minimize the possibility of crossing branches, choose a bud that is facing away from the interior of the plant.
When you cut a stem off, cut it at a 45 degree angle that matches the direction of the chosen bud. Be sure not to leave a long stem protruding past the location of the bud. This will prevent a fast and effective healing of that wound. Each cut you make on a plant exposes the dead-wood in the center of that stem. This exposure of dead wood eases the access of insects and disease into the plant. If the access point to that dead wood (the wound) heals over with live cells, it cuts off oxygen to that part of the dead wood and will kill many diseases that gained access while the wound was open. The faster a wound can heal, the healthier the plant will stay for the long term. Below is an image that displays the results of proper healing that is fostered by proper pruning cuts.
Each branch or stem has a group of cells at the base of that stem that are designed to close over a wound in that area. This section of the limb is called the “Branch collar.” It is the swollen section at the base of the limb where it first emerges from the trunk. See if you can find the swollen branch collar in the image below:
When cutting any limb off, you want to cut right at the edge of the branch collar, following its 45 degree angle against the trunk. You must avoid cutting into the branch collar as this would damage the plant’s ability to grow new cells over that wound. The most common erroneous cut that damages the branch collar and prevents healing over is called a flush cut (See image below.)
You must also avoid leaving too much stem protruding past the branch collar, as this simply leaves an obstruction that would prevent the cells from closing over the wound.
Additionally, it is very important to avoid removing heavy stems with a single cut. The weight of those stems can cause the branch to fall before the cut is completed, causing the bark on the bottom of the branch to rip off of the tree and leave a wound that will prove more difficult to heal.
The above can be avoided by using a 3-cut method on any stems that require a saw for removal.
The first cut should be on the under-side of the stem that is being removed, should be about 6” out from the branch collar, and should only go in ¼ to ⅓ of the depth of that stem.
The second cut will take place about 1-2” further out from the first cut, starting from the top of the stem and cutting all the way through until the branch drops to the ground. This will leave a 6” nub protruding past the branch collar that must be removed by the 3rd cut.
The third and final cut will follow the angle of the branch collar, and will leave the final wound in the best condition possible for a fast and effective healing. See the following image.
We hope these brief tips for pruning your landscape plants prove helpful for you as you seek to maintain visual balance in your landscape.
Don’t have the time to prune? Don’t want to spend your weekend pruning? Canopy can help! We can add pruning into your current plan, or give you a quote for a one-time pruning. Whatever your property needs, we’re here to help! You can send us a text, or feel free to email us at firstname.lastname@example.org.