English Ivy Facts, Uses, and Problems
A Beautiful and Annoying Plant
English Ivy is a beautiful plant with a long history. Some people value ivy for its ability to form an attractive cover over walls and tree trunks. Others consider the plant to be an annoying weed that damages the environment and must be eradicated.
English Ivy is native to Europe, western Asia, and northern Africa. The plant has been introduced to other parts of the world. Unfortunately, as an introduced plant ivy may have no natural enemies to control its growth and may become invasive. An "invasive" plant spreads rapidly and hurts native organisms.
Ivy is mildly poisonous. In addition, some people develop dermatitis after coming into contact with the plant. On the other hand, the plant may have health benefits. It has other benefits as well, even in North America, where it can sometimes be problematic. In this article I'll discuss English ivy from a North American perspective.
The English Ivy Plant
English ivy, or Hedera helix, is an evergreen plant that is found in many parts of Canada and the United States. Hedera hibernica is a similar plant that has also been introduced to North America and is often known as English ivy. In its native habitat the common name of this plant is Atlantic or Irish ivy. Like Hedera helix, it may become invasive.
The part of English ivy that most people are familiar with is the thick, lobed, and often glossy leaves. These are usually medium to dark green in colour and have light green, yellow, or white veins. There are three to five lobes on each leaf.
The leaves sometimes have an attractive variegated appearance consisting of two or more colours. The colours include dark green, light green, yellow, white, and red. English ivy can be found in a cultivated form as well as a wild one. The cultivated version of variegated ivy is a popular addition to plant containers and landscaped areas.
English ivy stems with lobed leaves are actually the juvenile form of the plant. The adult flowering stems have oval leaves instead. Ivy has yellow-green flowers that are borne in clusters. The flowers are generally produced in the fall in the part of North America where I live. They produce blue-black berries that don't ripen until late winter or early spring.
How Does Ivy Attach to Surfaces?
English Ivy is a climbing, trailing, and creeping vine. It develops long stems that become thick and very strong as they mature. The plant can climb as high as ninety feet if it has a good support.
An ivy plant has two types of roots. The subterranean roots extend into the soil, attaching the plant to the ground and absorbing water and nutrients from the soil. Clumps of adventitious or aerial roots are located at intervals along the climbing stems. The function of these roots (or rootlets, as they are sometimes called) is to attach the plant to a surface as it climbs.
Until quite recently it was thought that the only factor joining the adventitious roots to the support was a glue produced by the roots. New research indicates that the glue is not the only factor involved. A root actually changes shape to anchor the plant. It also produces root hairs that fit into crevices in the support.
Does Ivy Damage Walls?
Ivy may or may not damage walls. The topic is a controversial one. Some people say that the plant is destructive, causing walls to crumble as it clings to them. Others say that the plant actually protects walls.
Ivy is often said to cause walls to break down as it sends its roots into crevices. However, some researchers say that instead of causing crumbling, the plant often attaches to sections of walls that are already starting to crumble and have many crevices that the roots can enter.
Supporters of the plant say that ivy growing on the outside of a building helps a wall by providing thermal insulation, keeping it cooler in summer and warmer in winter. Some people claim that the plant traps water next to the wall, increasing structural damage, while others say that the waxy covering on ivy leaves repels water from the wall instead.
The English Heritage organization has studied the effect of English Ivy on walls. In 2010, they published the results of an investigation. They say that the plant can protect walls from heat, cold, humidity, and pollution. They also say that the rootlets cause no or very minor damage to walls. If there is existing damage to a wall before the ivy grows, however, the rootlets may penetrate the cracks and cause further harm.
It can certainly be difficult to remove ivy from a wall once it's attached, since it clings to the wall very tightly. Bits of plaster may be removed with the ivy and pieces of root and ugly marks may be left behind.
Effects on the Environment
English Ivy can spread rapidly and aggressively. It can be troublesome if its growth isn't controlled. In some parts of North America it grows all year. It thrives in shade but also grows in sunny areas. The plant tolerates a wide variety of soils.
Sometimes ivy is accused unfairly of crimes. For example, it doesn't damage tree trunks directly. It attaches to them with its adventitious roots, but these don't penetrate the trunk or absorb nutrients from the tree.
If there is a very dense growth of ivy it may damage trees indirectly. The ivy's weight may injure the tree. In addition, a sheet of ivy may act like a sail and make the tree more susceptible to damage caused by windstorms. The ivy may block light that the tree and other plants need for photosynthesis. Photosynthesis is the process in which plants use light energy to produce their food. English ivy is also said to trap water that increases the chance of plant disease, although as in the case of ivy growing on walls not everyone agrees with this idea.
In the wild, the creeping form of ivy can prevent light from reaching seedlings, causing them to die. The plant may also smother wild flowers and ferns. Some people appreciate ivy as a ground cover in their garden, however.
Research suggests that the plant can absorb particles that are polluting the air. English Heritage is one organization that has found evidence supporting this idea. They examined ivy growing beside very busy roads and discovered that it removed fine particles from the surrounding air. The organization says that they would like to do more research in order to determine whether their discovery is applicable to other areas.
Effects on Wildlife
English ivy has at least some benefits for the environment. It can be very helpful for wildlife in its native habitat. In Europe, the ivy on tree trunks provides a hiding place for a range of small mammals and a nesting site for birds. Unfortunately, in North America the "small mammals" that shelter in ivy seem to be mainly rats, especially the Norway rat, which is a pest. The nectar inside the flowers of English ivy is a food source for bees and butterflies in both Europe and North America. Some North American birds eat the berries. Far more European bird species feed on the berries, however.
Monarch Butterflies Feeding on Ivy Nectar
How to Control or Remove English Ivy
The war against unwanted English ivy can be won with effort and persistence. The task involves cutting the plant at frequent intervals (or all at once if the growth is small) and then digging out the roots. Protective gloves and clothing are useful, especially if a person develops dermatitis after touching the plant. Pruning shears, loppers, or a saw are needed to cut the stems, depending on their thickness.
Experts often say that when trying to remove a large ivy vine, cuts should be made at shoulder height and at ankle height. This may enable the vine to be unravelled from a tree trunk. However, some people recommend that the upper portion of the vine be left to die naturally and crumble (as it will do, since it no longer has a water supply) because pulling it down may damage the tree. Experts also say that a wide zone around the base of the tree trunk should be cleared of ivy to prevent or delay a new invasion. Once the ground is clear it should be covered with mulch.
A gardener will likely need to return to an ivy patch periodically to do more cutting, but the process usually becomes easier as the plant thins out. As soon as the soil can be reached, digging is necessary to remove the roots. It's important to realize that the plant can regrow from a piece of root or stem.
Once all of the ivy seems to have been removed, the area should be checked periodically to ensure that new plants aren't growing. Ivy is much easier to deal with when its stems are thin and relatively weak than when they are thick and strong.
Dealing With the Plant
Intact parts of the English Ivy plant should never be eaten. The plant is generally considered to be only mildly poisonous, but the dangers of plant ingestion increase with the amount that is eaten.
Ingestion of berries or leaf material in small quantities may cause no symptoms or only minor gastrointestinal upset. Ingesting large amounts of the plant can cause breathing difficulties, muscle weakness, coordination problems, fever, hallucinations, and even coma.
A standardized extract made from the English Ivy plant is generally safe, depending on how the extract is made. It may even be useful medicinally. A "standardized" extract is one with a known concentration of the active substance. This concentration is chosen for both effectiveness and safety.
Invasive Ivy in Woodlands
It's advisable to wear protective gloves when handling English ivy. The plant contains a substance called falcarinol that can cause dermatitis as well as blisters when people handle it. Dermatitis is a condition in which the skin becomes inflamed, red, and itchy. Both irritant contact dermatitis and allergic contact dermatitis can be caused by ivy contact. In irritant contact dermatitis, the skin is damaged by touching a substance. People with allergic contact dermatitis experience an allergic response after coming into contact with a substance that acts as an allergen. Interestingly, not everyone develops dermatitis after touching ivy.
In Europe, English Ivy extracts are used as an expectorant. An expectorant is a substance that relieves coughs by thinning mucus, enabling it to be coughed up easily. Ivy extract is approved for use by the German Commission E. This organization is a scientific advisory group that examines the safety and effectiveness of traditional herbal remedies.
There is a some evidence that English Ivy extracts help the coughs that develop in certain health conditions, but the extracts seem to work no better than other expectorants. Medicines containing guaifenesin are often used as equivalent expectorants in North America.
A Potential Anti-Cancer Effect
English ivy may have other health benefits for humans in addition to acting as an expectorant. Like other plants, ivy contains many different chemicals in a wide range of concentrations. Some of these chemicals may be helpful for us. Although the plant isn't currently used for either of the following applications, it may be in the future.
Falcarinol is found in carrots as well as English ivy. In carrots it acts as a natural pesticide that fights fungi. In one experiment, mice were fed freeze dried carrots containing falcarinol, corn starch to which an equivalent amount of falcarinol had been added, or corn starch on its own. All of the mice in the experiment were given a chemical that causes colon cancer.
After the experimental treatments were finished, the researchers examined lesions (damaged areas) in the animal's colons that typically enlarge and become tumours. The lesions in the mice that received falcarinol were significantly smaller than those in the mice that weren't given falcarinol. The researchers concluded that the falcarinol had delayed or slowed the development of cancer.
The mouse research is very interesting, but the discovery doesn't necessarily mean that falcarinol will have the same effect in humans. Results of lab experiments in rodents sometimes apply to humans, but not always. Even if the chemical is potentially helpful in us, scientists will need to discover the concentration that is both effective and safe. More research is necessary.
A Possible Sunscreen
The adhesive secreted by the root hairs of English ivy contain tiny nanoparticles that have been found to block dangerous ultraviolet radiation. They may be able to act as a safe human sunscreen.
Nanoparticles of titanium dioxide and zinc oxide are already used in sunscreens. There is some concern that the nanoparticles of these chemicals can travel through damaged skin and into our body, however, where they may have harmful effects. English ivy nanoparticles may be safer, although this hasn't been proven yet. More research is needed in order to determine the practicality of using an ivy sunscreen.
Ivy Alternatives for Gardens
Growing English Ivy
English Ivy is a beautiful plant. However, it's potentially harmful to the environment. Growing it deliberately requires caution. Landscapers and gardeners may love ivy, but its ability to grow invasively, hide pests, and interfere with the growth of other plants needs to be taken seriously. A dense growth of ivy can affect not only the ivy grower's garden but also their neighborhood.
The history of English Ivy in North America is a sad one, as it is for many introduced plants. Ivy is often referred to as a "noxious weed" instead of a valued part of its ecosystem. Some people may think that importing a plant from another part of the world either deliberately or accidentally is unimportant, but there may be serious consequences. Without the natural checks and balances that often develop during their long occupation in their native habitat, introduced plants may become invasive and damage their surroundings.
- Information about English ivy from NC State University
- English ivy as a medicine from WebMD
- Effect of falcarinol on mouse cancer from the NIH, or National Institutes of Health
- An English Heritage/University of Oxford report about the effects of ivy on walls
- Nanoparticles in English ivy may hold the key to making sunscreen safer and more effective from the ScienceDaily news service
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
Questions & Answers
Will English ivy live near an ocean beach?
English ivy is said to be moderately salt tolerant, so it would probably grow near a beach. It does best in soil that is rich in organic matter and in an area with at least partial shade, though it can tolerate sun. It would be best to plant it in a place that is protected from the wind, so it doesn’t dry out.
What fertilizer should I use for common ivy?
I have English ivy (or common ivy) in my garden. I’ve never fertilized the soil around the plant because it grows very well without the addition of chemicals. I’ve read that the plant often needs very little or no fertilizer, assuming it’s growing in soil containing organic matter. If fertilizer is required, garden experts recommend that it includes a balanced ratio of chemicals.
Specific number sequences show the amount of nitrogen, phosphorus, and potassium in a bag of fertilizer. For example; a 15-15-15 bag contains 15% nitrogen, 15% phosphorus, and 15% potassium. This is a ratio that is often recommended for English ivy, though I have no experience in using it myself. It’s important to follow the instructions on the fertilizer bag carefully, and to avoid sprinkling the fertilizer on the leaves of the plant.
When did the English ivy come to North America?
According to the Smithsonian Institution, English ivy was introduced to North America in the early 1700s by European colonists. The colonists appreciated the plant’s ability to create an evergreen cover over the ground and used it as an ornamental plant.
Can too much rain cause English Ivy to die?
Yes, it's possible, depending on where the ivy is planted. English ivy likes moist but well-drained soil. We get quite a lot of rain where I live. My English ivy grows well in this environment. If the soil became waterlogged and stayed that way, however, I would expect that the plants would be damaged and begin to die.
Does English ivy have the ability to grow through a brick wall?
The answer is often no, but in certain circumstances English ivy can destroy brick. It’s a very opportunistic plant. If the mortar holding the bricks together has been damaged and weakened by another factor or if the brick itself has cracks, is lose, or has started to crumble, ivy roots may penetrate the damaged area and make it worse.
© 2014 Linda Crampton