The Ultimate Guide to Trimming Suckers on Grafted Trees: Tips, Tricks, and Techniques

Unwanted suckers on grafted trees can be a problem for a growing tree and inhibit its ability to thrive properly. Trimming them is, therefore, an essential job, but as with many gardening jobs, there are a few factors that you need to take into account.

Not all species are as susceptible as others. We will look at the trees most prone to sucker growth, discuss ways to deal with the problem efficiently, and consider what can be done to prevent the problem from being too prevalent if you with future grafting.

Below we have laid out a few simple steps that will keep your tree looking its best and maximize its growth potential. In addition, we will also look at potential problems that can occur with over-zealous pruning.

Quick Guide for Fealing with Suckers on Grafted Trees

Below is a quick guide to dealing with suckers. Other factors also need to be considered, but these offer a good starting point for the task.

Step	Description
Locate the suckers on the tree.	They will typically be smaller and more slender than the branches of the scion. They may also have a different color or texture.
Winter is a good time to remove these suckers.	When the tree is dormant, it is a good time to remove suckers as it causes less stress to the tree.
Prune/ Cut-back the suckers.	Using a sharp pruning tool (such as a pair of scissors or pruning shears), cut the sucker off as close to the base as possible.
Dispose of the sucker properly.	Do not leave it on the ground near the tree, as it may regrow.
Monitor for the growth of new suckers	Be vigilant about removing suckers, as they can grow quickly and take over the tree if left unchecked. Trimming suckers multiple times throughout the year may be necessary to keep them under control.

In-Depth Look at Trimming Suckers on Grafted Trees

We have outlined the basic requirements and techniques for trimming suckers on grafted trees. Still, there are other considerations that you should take into account, such as general care, cold tolerance, and differences in care certain species require.

Grafted Trees that Are Most Prone to Sucker Growth:

The trees that are most prone to sucker growth are trees that have been grafted. Typically, the most susceptible are those grafted onto vigorous rootstocks. Commonly affected trees include fruit, apple, pear, and ornamental trees, such as Japanese maples and dogwoods. Rootstocks that are prone to sucker growth include M111, M26, and MM106.

Why Are Grafted Trees that Are Most Prone to Sucker Growth

Generally, the more vigorous the rootstock the cutting is grafted on, the more prone to sucker growth. Rootstocks are the lower part of a grafted tree, which provides the roots and lower trunk of the tree. They are chosen for their specific characteristics, such as size, disease resistance, and hardiness, with some rootstocks more vigorous than others.

The more vigor a tree has, the more likely it is to increase its susceptibility to sucker growth, as the rootstock can produce shoots (suckers) that compete with the desired scion (top part) of the tree for nutrients and water.

Factors other than rootstock can affect the propensity of a tree to o sucker growth. These may include the tree’s age, health, and growing conditions. For example, stressed or weakened trees may be more prone to sucker growth, as they may be less able to compete with the suckers for nutrients. Similarly, trees grown in nutrient-rich soil or receiving excessive fertilization may also be more prone to sucker growth. 

Trimming suckers:

Trimming suckers is highly recommended because doing so can help prevent them from taking/dissipating energy and nutrients away from the tree’s desired scion (top part). Suckers proliferate and can quickly overtake the scion if left unchecked, so it is essential to be vigilant about removing them. Trimming in the winter or early spring, when the tree is dormant, may also be less stressful for the tree than cutting during the growing season.

Tips for trimming suckers:

When trimming suckers, using a sharp pruning tool, such as pruning shears, will help ensure a clean cut. Using a dull tool or tearing the sucker off can damage the tree and create an entry point for disease. Use a saw or loppers if the sucker is too large to be removed easily with pruning tools. Be sure to properly sterilize your pruning tools before and after use to prevent the spread of disease.

As a general rule, when deciding what to cut, anything growing below the graft line and/or any growth that displays trifoliate leaves should be removed immediately

Risks and Drawbacks of Trimming Suckers:

Despite the general benefit of doing so, there are some risks and drawbacks to removing. While trimming suckers prevents them from taking too many resources and energy away from the scion, over-trimming or cutting away too many suckers at once can weaken the tree and reduce its vigor. 

Further problems include disrupting the tree’s natural balance, which could have unintended consequences. It is generally best practice to remove only a few suckers at a time rather than trying to remove them all at once.

Disposing of removed suckers:

After trimming unwanted suckers from a grafted tree, you should dispose of them properly to prevent regrowth. One option is to place the suckers in a compost bin or pile, where they will break down over time. Alternatively, the suckers can be burned or placed in a trash bag and disposed of in a landfill. It is generally best to avoid leaving the suckers on the ground near the tree, as they may be able to regrow if not correctly disposed of.

Frequency of Trimming Suckers:

The frequency of trimming suckers will depend on the specific tree and the growing conditions. Some trees may produce more suckers than others, and certain environmental factors, such as stress or fertility, may also affect the amount of sucker growth. 

It is usually a good idea to check for suckers regularly, at least once a month during the growing season, and remove any present. If the tree is producing many suckers, it may be necessary to trim them more frequently to keep them under control. However, as discussed, you should only remove a few at one go.

Other methods for controlling sucker growth:

Other than trimming, there are various other methods you can use to control sucker growth on grafted trees. One option is to apply a chemical growth regulator, such as naphthaleneacetic acid (NAA), which can help to inhibit sucker growth. However, it is crucial to follow the manufacturer’s instructions and use caution when applying chemicals to trees, as they can be toxic if ingested or cause skin irritation. 

Another option is to choose a rootstock less prone to sucker growth, such as a dwarfing rootstock, which can help reduce the need for sucker removal.

Benefits of Trimming Suckers:

There are a few other ancillary benefits to trimming suckers beyond just preventing them from diverting energy and resources from the scion. Removing suckers can improve the tree’s overall appearance and make it easier to care for. Suckers can also interfere with fruit production, so removing them can help increase fruit yield. Additionally, trimming suckers can help prevent the tree from becoming overgrown and allow more sunlight to reach the desired branches, improving the tree’s overall health.

Identifying Grafted Trees and Distinguishing Between Suckers and Desired Branches:

You can identify grafted trees by looking for a distinct “bark union,” which is the point where the rootstock and scion join together. The bark union may be visible as a swollen or raised area on the tree’s trunk. 

To distinguish between suckers and desired branches, look for size, color, and texture differences. Suckers are typically smaller and more slender than the branches of the scion and may have a different color or texture. Additionally, suckers may emerge from the tree’s base rather than from a higher point on the trunk or branches.

Different species of Trees Can React Differently to Suckers.

Some trees are more prone to sucker growth than others, and the tree’s vigor can also affect the amount of sucker growth. As mentioned above, fruit trees, such as apple and pear trees, may be more prone to sucker growth than some ornamental trees, such as maples or oaks. 

However, it should be noted that each tree is unique and is likely to respond differently to sucker growth. Factors such as the tree’s age, health, and growing conditions can all affect how a tree responds to sucker growth.