What is it?
Ivy is a woody stemmed, self-clinging climber that can grow quickly to cover fences, walls and buildings. It is a cause for concern owing to its rapid pace of growth and worries about potential damage to the support structure.
For more on the benefits of ivy and how to grow it, see our page on Hedera.
Appearance
Ivy is recognised by its dense, evergreen foliage. In its climbing state it has three- to five-lobed glossy leaves.
It attaches itself to supports by producing aerial roots along the stems. When the stems are pulled away from the wall, they often leave behind the unsightly root ends, that persist and can often only be removed with wire brushes or pressure washing.
The problem
Self-clinging climbers such as Boston ivy and Virginia creeper (Parthenocissus sp.) do not usually cause damage to wall surfaces, but common or English ivy (Hedera helix sp.) supports itself by aerial roots and where these penetrate cracks or joints they may cause structural damage. Sound masonry is unaffected.
Its dense cover can hide defects in the fabric of the building and hinder maintenance work. Ivy may also provide access for intruders and harbour pests such as mice.
Where brickwork is sound, the main problem is to keep growth away from gutters and paint work.
It has been suggested that vegetation attached to walls could lead to dampness resulting from slower drying conditions following rain. This may be plausible on a south-west facing wall where the rain is driven by prevailing winds. However, other sources suggest that such plants will have a slight drying effect on mortar and will also provide some degree of insulation in winter, particularly evergreen ivies covering exposed north and east-facing walls.
Large climbers can pose a risk to buildings. Such problems are most likely with older property, those with shallow foundations and those built on clay soils.
Control
When to control
When undertaking work on ivy check that there are no birds nesting, as it is an offence under the Wildlife & Countryside Act 1981 to damage or destroy the nest of any wild bird while it is in use or being built. The bird nesting season is usually considered to run March to August (though it may last longer for certain species or multiple broods so always check if in doubt).
Non-chemical controls
Where possible, use non-chemical methods. The stems should be cut back to the ground and the woody stump dug out.
If proximity to foundations prevents removal, regular cutting of the stems to ground level may weaken the ivy over time, but is unlikely to kill it.
See section below on RHS research into preventative methods of control using metal sheeting or paints.
Chemical controls
- Ivy can be killed by severing the stem and treating the stump with a proprietary stump and rootkiller based on glyphosate (e.g. Scotts Roundup Tree Stump & Rootkiller, SBM Job done Tough Tree Stump Killer (soluble sachet only), Doff Tree Stump & Tough Weedkiller and Westland Resolva Extra Tough Weedkiller, Westland Deep Root Ultra Tree Stump & Weedkiller) or triclopyr (Vitax SBK Brushwood Killer)
- Top growth may be treated with glyphosate or triclopyr also, but ivy is not easily controlled by weedkiller sprays due to the glossy nature of its leaves. Repeat application may be necessary. Once the foliage has been killed, it can be pulled from the wall
Dead foliage and stems are relatively easy to remove from walls but aerial roots are persistent and can only be removed using a hard brush or paint scraper.
Inclusion of a weedkiller product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.
Download
Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 1a and 4)
Links
Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers
Weeds: non-chemical control
RHS research into preventing ivy attachment
Ivy, with its strong attachment to walls, can be a worry to homeowners, concerned about whether it might damage wall surfaces or block gutters. Growing ivy or other climbers up a building wall can, however, have many benefits; vegetative cover can insulate and cool the building, trap pollutants and attenuate noise.
Options to control or prevent ivy attachment were therefore investigated within a part RHS-funded PhD project, based at the University of Reading. A series of experiments with two ivy species (Hedera hibernica and H. helix) was conducted using both a laboratory model system, but also mature H. helix growing up a wall.
Results
Metal sheets:
Copper and zinc sheets, as well as dense copper mesh, completely prevented ivy attachment, while otherwise not compromising healthy plant growth.
Paints:
- Application of two coats of ‘Easy-On’, a clear anti-graffiti, silane-based, nanoparticle paint, was as efficient in preventing attachment
- Application of another, petrochemical-based paint, while not completely preventing ivy attachment, significantly weakened it, thus easing ivy management
Read the full paper with details on chosen deterrents and possible mechanisms which make them effective.
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