Ivy has the property to climb up trees and overgrow them. This looks nice, but is it also good for the trees or must the ivy be removed?
Originally, ivy grew in forests and looked for a way from the forest floor up to the light. This, of course, led over the tree trunks. But ivy also thrives excellently in the home garden, without losing sight of the old growth direction. As a gardener, you are right to ask yourself whether you should leave the tendrils on the trees or rather remove them.
Does the growth cause harm?
The question often arises whether ivy that makes its way along trees is harmful or not. The trees could choke on the vine or the shoots could break off. But the roots of the plant could also damage the tree.
Some of these fears are unfounded. Ivy develops different roots. It gets its nutrients from the soil with its soil roots. For climbing, it uses its adhesive roots. A healthy, strong and already mature tree is not harmed by ivy. The situation is different with young trees. These often have very thin bark that could be damaged by the adhesive roots. Also, the branches may bend downward and break off. However, this only applies to very young trees. Weeping willows, whose branches protrude downward anyway and are very thin, are also problematic. The ivy can become too heavy and damage the branches.
How does ivy adhere to the tree?
Unlike mistletoe, for example, ivy touches the bark only on the outside and does not penetrate the bark with its adhesive roots. Therefore, the climbing plant does not injure the tree, nor does it absorb nutrients from the trunk. If the bark of the tree has cracks, however, the adhesive roots may become embedded.
Despite its vigorous growth, the tree also receives sufficient sunlight through its foliage. Ivy prefers to stay in the shade, so densely foliated trees are ideal climbing aids for the plant. Since ivy rarely overgrows the entire tree crown, the tree also receives sufficient sunlight here.
Conclusion: Ivy does not need to be removed
To protect the tree, you do not need to remove ivy. Exceptions are:
- young trees with low growth height
- weakened trees with damaged bark
- fruit trees
Damage to the bark can lead to the establishment of adhesive roots and provide an ideal climate under the ivy for fungi that can damage the tree. Fruit trees are also suitable for greening only to a limited extent, because it is not uncommon for insects to settle in the ivy, which can have a negative effect on the fruit harvest. How you can then remove the ivy, you can learn here.
Does Ivy Break Trees?
The image of ivy is not positive among all tree lovers. In addition to the supporters, who enjoy the green sight of the overgrown trees, especially in winter, there are numerous rejecters of the climbing plant. Often they have clear ideas about the behavior of ivy on its support tree. Due to incorrect or inaccurate conclusions, myths gradually emerged. Although ivy can be a threat to many trees, most of the rumors surrounding ivy are not true. A clear differentiation between myth and real problems sheds light on the ivy’s way of life.
Myth: The Bloodsucking Ivy
Even the Greek philosopher Theophrastos of Eresos (c. 371 – 287 B.C.), also known as Theophrastus, described the ivy as a parasite. He thought its roots acted as straws, depriving the tree of vital water and nutrients. While this opinion seems obvious given the many fine roots on the trunk, it is incorrect. Ivy has different types of roots. It is anchored by its soil roots, which also supply it with water and nutrients. That is why they are called nutrient roots. So-called adhesive roots also grow from the trunk of the ivy. They serve only one purpose: to attach the shoots and thicker stems of the plant to its supporting tree, thus enabling it to grow upwards into the crown. However, they are not capable of absorbing water and nutrients.
Sporadically, it happens that adhesive roots transform into nutrient roots. If young adhesive roots are in contact with soil or sufficient water, they simply change their strategy. As a result, they are able to grow into moist crevices in stones or dead trees. Also, cracks in vital trees may cause ivy to grow to the moist environment inside. If the tree then grows thick, it often looks as if the ivy has grown into the tree.
True parasitic climbers can also be found with mistletoe which feeds mainly on its host and does not even have roots anchored to the ground. They form “haustoria” with which they penetrate the leading vessels of the trees. Ivy does not possess such adaptations.
Myth: The Shady Ivy
Ivy plants grow meters high into the crowns of trees. This is where the fear comes from that it takes the light away from the trees to grow. However, it is necessary to take a differentiated view. The best support trees for ivy are large, stately individuals. On them, the climbing plant grows up the trunk. This saves resources and ensures the ivy a place in the sun. These trees have wide spreading crowns. Leaves for vital photosynthesis are located where the most sun reaches: on the fine branches at the top and sides of the crown. Ivy, on the other hand, grows mainly on the trunk and thick supporting branches. Thus, it rarely comes into light competition with the tree.
The Shady Side
The situation is different for smaller or young trees. Here the ivy can overgrow the entire crown and thus cause the tree to die. This is not so rare. The ivy tries to get light through its supporting tree and, of course, does not stop there if it has the opportunity to occupy its place above the crown. Even if the tree dies, the dead tree skeleton remains for years as a support for the ivy. The thinner the crown of a tree, the easier it is for ivy to climb upward. Dense crowns cast a lot of shade and slow down the ivy. Coniferous trees are therefore far less likely to be overgrown than large-crowned deciduous trees.
To make coexistence of ivy and supporting trees possible for both, arborists must intervene. They regularly remove ivy shoots from the crown so that only the trunk is shaded. This actually benefits the tree, as the leaves create a good microclimate, protect from the sun, and provide nutrients as they rot. Competition in the crown is banished and the positive properties of ivy are preserved.
Myth: The Suffocating Ivy
Ivy usually forms a dense cover of leaves around the trunk. The assumption is that this prevents light and air from reaching the bark and slowly suffocates the tree. However, there is no evidence for this. The opposite is true. Trees that suffer from sunburn, such as copper beech, hornbeam and ash, benefit from the shading of their trunks. It only becomes dangerous for the tree when man, in his protective rage, clears the trunk of ivy. For years it has not had to protect itself against the sun and is now at its mercy. The resulting damage is not due to the ivy but to man. Also, the growth could protect against frost cracking because it mitigates fluctuations in temperature.
PROBLEMS IN TREE CARE
Nevertheless, the dense canopy of ivy has one significant disadvantage. Leaves and stems almost completely obscure the trunk of the supporting tree, making it almost impossible to perform tree inspections. This is hardly a problem in the forest. In parks, along roads and in gardens, where traffic safety is a major concern, it is a real problem. The checks to see whether the tree is still stable, has wounds or suffers from fungal attack take much longer than for a “bare” tree. This drives up costs and, in the worst case, leads to problems being overlooked.
Myth: The Strangling Ivy
Because of the ivy’s thick climbing trunks, there is a fear that it could literally strangle the tree. The ivy stems mostly grow up one side of the supporting trunk. Compared to honeysuckle, which grows looping around the trunk, ivy does not actively constrict the supporting trunk. It grows where there is light. Especially in forests, this is more often from one side, which is why ivy rarely climbs up both sides of the tree.
Thickness Growth And Anchor Points
Over time, the intergrown branches of the ivy trunks form a kind of corset. The thickness growth of the supporting trunk and the ivy stems exert pressure on the bark. In bad cases, the trees can even partially grow around the ivy stems like foreign bodies. This can weaken the stability, as the thickness growth is less constant in some places. At the same time, the thick stems of ivy in the crown make it cumbersome for arborists to climb. They can poorly see from below which anchor point is holding and which has possible damage. Also, ivy is often visited by bees and wasps in the fall, which can make life difficult for arborists.
Removing ivy can be harmful to the tree’s bark.
Myth: The Stunning Ivy
Ivy can spread extensively in the crown of trees, providing additional surface for wind and snow to attack. This is especially a problem for smaller or already weakened trees. Tall and vigorous trees can usually compensate for the extra weight and increased attack surface. Its sail effect is higher in percentage, the smaller the overgrown tree is. Thus, there is an increased risk of windthrow and snowbreak here.
Myth: The Thieving Ivy
Since the ivy trunk ends directly at the supporting trunk, both plants root in the same soil. Thus, there is a possibility that the ivy will weaken its support tree by competing for water and nutrients. However, it has been confirmed in various experiments that trees with ivy growth often grow better than trees without growth. This comes from the fact that ivy foliage has hardly any decomposition-inhibiting substances. It has a positive influence on the turnover of substances in the soil. In addition, the delayed leaf fall of ivy in the spring provides a continuous supply of nutrients to the trees.
Does Damage Benefit The Ivy?
What is the ivy’s motive for damaging its carrier plant? Looking more closely, it is clear the ivy initially benefits from a healthy, growing support tree. Its goal is to reach the upper layers of the forest in as short a time as possible. It usually takes thirty to forty years for it to accomplish this. Once at the top, an easy life in the sun awaits him. If he damages his tree so much that it dies, he has already reached the upper level and can rest on the tree skeleton. Only when the tree falls down, the ivy is at a disadvantage. It has to look for a new supporting tree to avoid living in the shade of the other trees. This sets it back years in development! The ivy benefits from its support tree simply by the height and stability of its trunk. The problem with this is that the ivy does not actively choose its trees. It does not stop when the support tree threatens to die. The interaction between the ivy and the support tree is therefore almost always at a standstill. Like almost all plants in the forest, they compete for light and nutrients.
Tree Care As A Regulating Element Between Ivy And Tree
So what to do? Trees that are regularly checked for stability should remain free of ivy as much as possible. If control is possible despite ivy, arborists can keep the ivy in check from the base of the crown. In woodland or unproblematic locations, allow ivy to grow unimpeded in trees. It is a true miracle plant for nature and a vital source of food and habitat, especially for insects and birds.