Ivy: A Green Nuisance Or Wildlife Welcomer?

Guest post by Sarah Gerhardt

Gardeners’ opinions are divided when it comes to ivy. Whether you appreciate the evergreen plant or see it as a clinging nuisance will probably depend on where and how vigorously it is growing in your garden. Today’s blog post explores the many positive traits of ivy, some of which we may not be aware of as gardeners. We will take a look at how we can manage ivy sustainably and how we can mitigate some of the problems it can cause us in the garden.

Wildlife Habitat

Common ivy (Hedera helix) and Atlantic ivy (Hedera hibernica) are British native plants and as such well adapted to the climate and ecosystem of the British Isles. They are year-round sources of food and shelter for a large number of insects, birds and small mammals.

Ivy still flowers late in the season which makes it an important food source for insects such as bees, common wasps and hoverflies before they go into hibernation. It is also a lifeline for autumn flying butterflies and moths. In winter a ground covering of ivy helps retain some warmth in the soil and it is less likely to freeze. This means birds and other animals are still able to forage and find food among the ivy leaves.

The dark blue berries of ivy ripen in early spring, a time when most other food resources have been exhausted. With their high fat content they are a superfood for birds. Numerous different garden birds such as thrushes, blackcaps, wood pigeons and blackbirds feast on them. In summer, the caterpillars of many butterflies and moths feed on ivy leaves.

Ivy is also great as a plant that provides shelter. Thick patches of ivy are used as a roosting site for bats and birds, and provide a home for hibernating insects. Birds that like to build their nests in ivy include wrens, robins and dunnocks.

Versatile & Reliable Grower

The value of ivy to wildlife is undeniable and it also has many benefits as a garden plant. Ivy is hardy and thrives in most conditions. It is easy to grow and simple to prune and shape. Its ability to cling and create dense layers allows it to fill in any gaps and holes with ease. Ivy can tolerate deep shade and works as a naturalistic backdrop for any garden schemes and planting styles.

There are many cultivars of ivy that come in various leaf colours and patterns. These cultivars can be an excellent option as evergreen groundcover plants. Look out for cultivars such as Hedera helix ‘Goldheart’ which produces dark-green leaves with a golden centre or Hedera helix ‘Glacier’ with its attractive grey-green leaves and white margins.

Managing Ground Covering Ivy

Ivy is a fast-growing and vigorous plant. A single plant can cover several metres of bare ground and it roots from its stems as they creep along the ground, effectively creating new plants as layers. It can smother smaller plants in the process. Ivy can grow along hedges and over fences which allows it to be easily introduced from a neighbouring garden.

Ground covering ivy can be kept under control by pruning back the stems with secateurs and digging up sections where they have rooted outside the area where the ivy cover is wanted. Smaller pruning of ground covering ivy should be done regularly during the growing season to keep it in check.

Any more drastic reductions should only be carried out outside the nesting season. Nesting season lasts from about March to October so the best time to prune ivy is between November and February. Always check for bird nests before pruning a thick patch of ivy even outside nesting season as birds sometimes have a second brood late in the season or start building their nest early.

Alternatively, ground covering ivy can be kept in check by smothering it. In winter, remove all top growth using shears or a strimmer. Then cover the remaining ivy stems with cardboard, followed by a 20 cm layer of thick organic material such as bark chips. Instead of cardboard and mulch you can use a biodegradable mulch matting. The mulch layer will block out the light which will slowly kill the root system. This may take a couple of years and the mulch layer may need topping up from time to time.

Since ivy grows so readily, prunings should not be added to the compost bin. The prunings are likely to take root in it. Instead dispose of ivy clippings via your local green waste recycling scheme. Or you can make a pile and leave them to rot down separately in a sheltered spot out of the way. The clippings will take some time to break down but will eventually turn to mulch which can then be used in the garden. In the meantime the pile of ivy clippings makes a wildlife home.

Does Ivy Strangle Trees?

There is a common belief that ivy strangles trees. This is not entirely correct. While ivy can quickly smother smaller plants it does not directly endanger the health of large trees. Ivy is not a parasitic plant. The aerial roots of ivy attach themselves to tree bark for support only and do not penetrate it so there is no direct competition for nutrients. The competition for water and nutrients at ground level and for light at canopy level is not an issue for healthy mature trees.

However, in some cases it is advisable or at least desirable to remove ivy from trees. Remove ivy from young or newly planted trees as they are getting established. These trees need optimal support with all vital nutrients and light to become healthy mature trees.

Likewise, old, weak and damaged trees may struggle with the competition from ivy. Existing issues on the tree such as cavities or decay may be obscured by the ivy cover and the weight of the ivy on the tree could make it unstable, especially in a storm. Some trees have small canopies (for example larch and ash) which puts them at higher risk of being outcompeted for light by a heavy covering of ivy. On these trees it is advisable to keep the ivy growth in check.

Lastly, if a tree is grown for its ornamental bark, such as many Acer species, for example the Paperbark Maple (Acer griseum) and birches such as the Himalayan birch (Betula utilis subsp. jacquemontii) the gardener may like to remove ivy for aesthetic reasons.

Managing Vertically Growing Ivy

When growing vertically, ivy roots are incredibly adaptable ‘shape-shifters’ to allow the plant to grow up a range of different surfaces. The tiny roots cling to its support such as trees, rocks or buildings and attach themselves by secreting a clue-like substance that provides a tight hold. In addition the roots can spiral themselves around an attachment point.

Climbing ivy produces seed once it matures but this can take over 10 years to happen. The berries are eaten by birds who then may spread the seeds a large distance from the ivy plant where they may germinate. Ivy seedings can easily be removed before they become established.

To remove ivy from trees cut across all stems at ground level. Use loppers or a saw for mature ivy stems. Take care not to cut into the tree bark while doing so. Severing the stems will kill the ivy that is already growing up the tree. It will die off and can then be removed more easily or left as shelter for wildlife.
Digging out the ivy root will ensure that the ivy does not grow back. However, this is often not possible if it is growing close to the tree. In that case ensure to take off about 1 m of ivy on the tree between where you cut across the stems and the root base. The ivy will grow back from the root base but it will be easy for you to see when it is starting to creep up the tree trunk again. You will have to keep monitoring it and remove any new ivy shoots as they appear. This will gradually weaken the ivy plant.

Controlling Rather Than Trying To Eliminate Ivy

Since ivy is such an incredible plant for wildlife it is better to control its spread than trying to remove it completely. While the mentioned methods of managing ivy can be time-consuming they are effective at keeping it in check. Cover your arms and legs and wear gloves when working with ivy. It can irritate the skin on contact and is harmful if eaten. So make sure that pets and kids do not munch on it.

It is not advisable to try to combat ivy by spraying weedkiller. Apart from detrimental effects to the environment, spraying weedkiller is often ineffective because it will not readily penetrate the plant. Ivy leaves are glossy and moisture-resistant and it may take several applications for the weedkiller to have any effect on the plant.

Remember to always check for nesting birds before you do any work to control or remove ivy. It is in fact an offense to destroy a wild bird’s nest that is in use or being built (Wildlife & Countryside Act 1981). As much as possible limit the work to the winter months when you are less likely to disturb an active bird’s nest.

Try to embrace the ivy in your garden. While it may need some controlling in your borders or up your trees the local wildlife population will thank you for leaving some areas of ivy.

About the author: Sarah Gerhardt is a gardener, linguist and punk musician based in Edinburgh. She was head gardener at the Dean Gardens, Edinburgh for 9 years and runs her own gardening business Gerhardt’s Garden Service. Find out more via her Linktree: https://linktr.ee/gerhardtsgardenservice