We need hedges! But what sort?

Cover image

Hedges are often the first casualty when front gardens are paved for parking.

That’s a huge loss because hedges boost urban life in many ways, and we need more, not fewer, hedges, especially on residential streets.

Unsung heroes

Research shows that hedges do so much to make towns and cities more liveable. They help absorb some air pollution. They help moderate temperatures in towns – a rising problem as towns tend to be hotter than rural areas, and excess heat is increasingly implicated in public health problems and even higher death rates.

Hedging also helps cut noise levels (a common complaint in busy urban areas) and also takes up rainfall and surface water which can add to flood risk. For good measure, hedging also stores carbon and decontaminate polluted soil. Not bad for a humble hedge.

What’s more, hedges provide shelter and food for insects and birds (supporting urban nature), help with security and privacy, and contribute to a green, aesthetically pleasing and stress-relieving environment.

Some London boroughs have begun putting in hedges a lot – beside roads and schools, in new developments and new road layouts, beside paths. This is because they are now known to provide many of the same benefits as large trees and parks, but take up less space and can be fitted into all sorts of small spaces and corners.

Exactly the same applies to front gardens, so it’s much better to keep existing hedges and plant new ones than to replace them with walls and fences.

Photo of Forsythia creating a hedge together with an ivy-covered wall
Forsythia and ivy creating a hedge

Not all hedges are the same

Some types of hedging plants are more beneficial than others.

Researchers from the Royal Horticultural Society and the Universities of Reading and Sheffield have been investigating which hedge plant species used in towns and cities deliver the most benefits. They have assessed the available research and published a review of common urban hedge species by their benefits (as currently understood).

Nearly all hedge species provide some benefits, but some are particularly strong.

All-rounders: On current information, the best all-rounders are beech (Fagus sylvatica), hawthorn (Crataegus monogyna), holly (Ilex aquifolium) and Japanese rose (Rosa rugosa).

Photo of a driveway with a privet hedge on each side
Privet hedges in Ealing

Air quality: Particularly good at absorbing air pollution are beech, yew, bay laurel, privet, Elaeagnus and Photinia. Hairy and narrow leaves are good at trapping particulate air pollution (tiny sooty particles). Some of these can also produce allergenic pollen when they flower, which can be a problem – seasonal pruning can help lessen this.

Wildlife: Many hedge plants support wildlife by providing shelter, nest sites, food such as nectar for bees and other pollinating insects and autumn berries for birds, and corridors for movement. A mixed hedge of several different species helps maximise biodiversity.

Photo of a hedge containing several shrub species including privet, cherry laurel and Photinia
Mixed species hedge in Ealing

Noise: Large evergreen leaves and dense hedge structure seem to be particularly effective in reducing noise, for example holly, Photinia, Prunus laurocerasus and some Berberis species.

Flooding: Because so many front gardens have been paved over to lower maintenance needs or provide parking, former gardens have few or no plants, adding to rising flood risk.

Hedges can help reduce this by intercepting and delaying rain reaching the ground, and taking up and transpiring water, readying the soil to absorb the next lot of rain. There’s not much information about the best species because most of the relevant research is on trees and not heavily-pruned hedges, but Forsythia is one species known to have a high transpiration rate.

Hedge benefits

I’ve compiled the following list of hedge species from the published review. This, together with information about preferred growing conditions from plant suppliers or the RHS (https://www.rhs.org.uk/plants) may be useful if you’re planting a hedge or with re-appreciating and maintaining an existing one.

Hornbeam (Carpinus betulus): Air pollution, Rainfall, Decontamination, Biodiversity, Health and wellbeing

Beech (Fagus sylvatica): Air pollution, Noise, Carbon sequestration, Decontamination, Biodiversity

Berberis thunbergia: Air pollution, Noise, Decontamination, Security & privacy

Box (Buxus sempervirens): Air pollution, Noise, Rainfall, Biodiversity

Camellia japonica: Air pollution, Rainfall, Decontamination, Health and wellbeing

Hawthorn (Crataegus monogyna): Air pollution, Noise, Biodiversity, Security & privacy

Euonymus japonicus: Air pollution, Noise, Carbon sequestration, Decontamination

Holly (Ilex aquifolium): Air pollution, Noise, Carbon sequestration, Decontamination

Bay Laurel (Laurus nobilis): Air pollution, Noise, Carbon sequestration, Decontamination

Viburnum tinus: Air pollution, Carbon sequestration, Decontamination, Biodiversity

Forsythia spp. and cultivars: Temperature, Rainfall, Biodiversity

Lavender (Lavandula angustifolia): Decontamination, Biodiversity, Health and wellbeing

Privet (Ligustrum ovalifolium): Air pollution, Decontamination, Biodiversity

Firethorn (Pyracantha coccinea and cultivars): Noise, Decontamination, Biodiversity

Rosa rugosa: Air pollution, Decontamination, Biodiversity

Yew (Taxus baccata): Air pollution, Decontamination, Biodiversity

Mexican orange blossom (Choisya ternata): Biodiversity, Health and wellbeing

Hazel (Corylus avellana): Decontamination, Health and wellbeing

Cotoneaster various species: Temperature, Biodiversity

Oleaster (Elaeagnus × ebbingei): Air pollution, Decontamination

Griselinia littoralis: Noise, Biodiversity

Veronica (Hebe spp. and cultivars): Noise, Biodiversity

Lonicera nitida and cultivars: Temperature, Noise

Photinia fraseri: Air pollution, Decontamination

Phyllostachys aurea: Air pollution, Carbon sequestration

Cherry Laurel (Prunus laurocerasus): Air pollution, Temperature

Snowberry (Symphoricarpos albus): Decontamination, Biodiversity

Thuja plicata: Rainfall, Carbon sequestration

Spindle (Euonymus europaeus): Biodiversity

St John’s Wort (Hypericum × hidcoteense 'Hidcote’): Biodiversity

Flowering Currant (Ribes sanguinium): Biodiversity

Skimmia japonica: Air pollution

Weigela florida: Air pollution

Based on research published by: Tijana Blanusa, Michael Garratt, Margaret Cathcart-James, Leigh Hunt and Ross W.F. Cameron, Urban hedges: A review of plant species and cultivars for ecosystem service delivery in north-west Europe, Urban Forestry & Urban Greening 44 (2019)