Managing Ivy Growth

Survey

Before any ivy is removed, it is good practice to carry out a survey. This should determine, as far as possible, how much consolidation and repair works will be needed to stabilise the structure once the ivy is removed. We want to avoid a situation where removing the ivy can be unsafe or reveals a need for urgent repair work, but funds are not available. In some instances, it may be necessary to trim the ivy before carrying out the survey.

Aerial roots growing on the surface of a building do not need to be removed. Ivy rooting into the structure of a building does need to be removed, as soon as possible. Removing a few small pieces of stem from various parts of the structure will allow checks for possible rooting into the building fabric. If the ivy has rooted in one location, it may also have rooted in another. If a healthy ivy has no main stem rooted into the ground, it will most likely have rooted elsewhere into the structure.

Ecological assessment

To avoid disturbing wildlife, an assessment should be carried out by a registered ecologist before ivy is removed. Removal works should be scheduled for autumn/winter, and completed before February when the bird nesting season (late February to the end of July) starts again. Works must also be timed to avoid disturbing bats.

Options

Option 1: do nothing

As described above, ivy growing over a wall can bring numerous benefits. If it is not rooting into the structure, and there is not too much flowering growth that could destabilise the structure, sometimes it is best to do nothing.

It may be best to do nothing if:

• The ivy is protecting a vulnerable surface that would be subjected to erosion and weathering if exposed
• There are no funds for essential repair work to the building fabric beneath the ivy
• There are no funds for maintaining an ivy-free wall in the longer term
• A screen of vegetation helps protect the structure from vandals
• Regular inspection of the masonry structure beneath is not essential
• The ivy does not detract from the appearance of the site

However, if the fabric is in danger and at immediate risk of loss, doing nothing is not an acceptable option

Option 2: cut back

Growing or flowering stems can be cut back without killing the ivy or harming the masonry structure beneath. Cutting back should be done regularly (yearly or every couple of years) to keep growth in check.

It may be best to cut back if:

• Flowering stems are beginning to rub against parts of the structure
• The mass of stems, particularly flowering stems, might destabilise the structure
• Growth is close to a vulnerable or visually important part of the structure
• The ivy is growing into roof spaces or over gutters, downpipes, windows and entrances

Option 3: remove (partially or completely)

Sometimes ivy will need to be partially or completely removed. This always needs to be done carefully, otherwise you might make the situation worse. Our research clearly shows that severing ivy at the base, and leaving the stems and foliage to die, can trigger the plant to root into the structure. It is essential that the juvenile stems are fully removed from the cutting point forwards to the growing tip, because any portion of stem left between the cutting point and the growing tip will attempt to form proper roots.

Be aware that forcefully removing ivy stems can damage the substrate underneath, particularly if it is in poor condition.

Often, ivy needs to be partially removed to reveal whether it is damaging masonry. Partial removal might also be a good option if funds are limited, or if a temporary 'holding operation' is required.

Removing the ivy completely might be necessary if the continued growth of stems and roots is damaging the structure. It might also be necessary to carry out repairs to the fabric.

Complete removal is advised if the ivy is:

• Rooted into the structure
• Growing within the core of the wall or through cracks/gaps/holes in the wall
• Growing in eroded or recessed mortar joints
• Growing around or over protruding stones, such as capping stones
• Growing between faults or cracks in the structure

Ivy may need to be removed if it is obscuring the architectural significance of the structure.

Dense ivy growth is often a problem in cemeteries, burial grounds and churchyards. Care must be taken when removing it, because there may be hidden dangers, such as loose stones or holes. Caring for Historic Cemetery and Graveyard Monuments includes a 1-page guide and a condition survey form for carrying out a monument and memorial survey.

Removing ivy

Removing ivy is a 2-phase operation. In the first phase, the long stems should be cut back close to the wall surface. In the second, the remaining ivy growing over the surface of the structure should be removed. This approach:

• Allows for assessment of the structure to decide how much ivy needs to be removed
• Reduces the possibility that the structure will be damaged by wind (a heavy mass of mature ivy growth can catch the wind and destabilise the wall)
• Stops the remaining ivy from re-rooting into the structure if work is paused at any point
• Makes the ivy less attractive to nesting birds

Removing stems

Ivy stems should be removed carefully in small sections, to avoid dislodging or damaging masonry. This is particularly important if the structure is not in good condition. Any attempt to pull off large sections of ivy could bring down parts of the structure.

It is usually best to start removing stems from the top and outer edges. The youngest growth at the top is often the hardest to remove, as the young aerial roots adhere tightly to the surface. Older stems farther down have little or no attachment to the structure. If you start from the top, the removal work will become easier as you move down the wall. If you start at the bottom, it is very tempting to pull at the stems, to try to get as much off as possible. Tugging is dangerous because it may pull out loose stones, bricks or mortar. As noted, if stems are cut at their base, and then the work is abandoned, the ivy may root-in higher up the wall and cause more damage.

Removing rooted-in growth

If ivy is already rooted into the structure, work can be started at any point. However, starting at the edges and working back to the main stem may be the best and safest method.

Where ivy has rooted-in, you will need to tease out the proper roots. Most of them will be in the mortar joints, although some may be found growing in cracks or flaws in the stone. It may be possible to gently pull the whole root out, if it is small. Larger roots may need to be cut out. If roots or stems are thicker than 10 millimetres, it may be necessary to consolidate or re-point the structure once the vegetation has rotted away.

All cut surfaces should be treated immediately with herbicide to prevent regrowth. There may be dormant buds where the roots become stems; these are difficult to see and can regrow. Checks will need to be carried out the following year, and any regrowth cut back and treated.

Stumps can be dug up (this will require a Scheduled Monument Consent if the area is scheduled), or left and treated to prevent regrowth. The RHS also provides advice about ivy on buildings, including weed killer controls.

Protecting wall surfaces

If the structure is in poor condition, you may have to prise stems and aerial roots away from the surface. This can usually be achieved by sliding a thin blade or scraper beneath the stem and levering upwards. Care must be taken to avoid damaging the masonry surface, especially where the building materials are fragile and friable, or where there is a risk to architectural detail and finish; in these cases, it may be necessary to use wooden implements rather than metal to avoid damage.

Controlling ivy

The RHS, with the University of Reading, has investigated options to control or prevent ivy attaching to surfaces. Their research shows that some paints or copper or zinc sheets may be effective. However, these options may not be appropriate for historic buildings.