Gardeners should consider swapping walls and fences for hedges, says the Royal Horticultural Society (RHS), as new research shows how they provide a range of frontline environmental services. The call forms part of the charity’s Greening Great Britain campaign which urges the public to turn urban concrete corners into thriving green spaces.
Hedges, Plant a Nature Screen
Analysis by the charity of 44 of the most popular hedges, found that as well as mitigating flooding, capturing pollutants and acting as a sound barrier they can also be used to help heat and cool the home. Hedge species in urban environments were also found to provide a crucial resource for a wide diversity of animal species through the provision of shelter, nest sites, food resources and corridors for movement.
The best all-round performers suitable for UK gardens include beech, holly, privet, western red cedar and rose.
The varying structure of hedges makes them well suited for specific roles. Those with hairy, rough and oval leaves, were found to better capture and retain particulates with dense, but porous canopies capturing the most. A yew canopy exposed to roadside pollution can accumulate and retain, for example, four times more particles than Photinia which has smoother leaves and is less dense.
Meanwhile wide, tall and layered evergreen species have been shown to act as sound barriers with English yew (Taxus baccata) and western red cedar (Thuja plicata) found to be the top performing.
RHS hedge planting guide:
|Hedges for…||Have these desirable features…||And include…|
|Particulate capture||Large and dense canopy (at least 1.5 m high and 1 m deep); smaller ovate, hairy, scaly or rough leaves||Cotoneaster, English yew (Taxus baccata), Western red cedar (Thuja plicata)|
|Noise reduction||Wide, tall and multi-layered vegetation belts with evergreen species of dense canopies||English yew (Taxus baccata), Western red cedar (Thuja plicata), Japanese barberry (Berberis thunbergii), cherry laurel (Prunus laurocerasus), holly (Ilex aquifolia)|
|Flood mitigation||Plants with a largeleaf surface, higher transpiration rates andevergreen canopies have been associated with greater rainfall retention||Hawthorn (Crataegus monogyna) and Forsythia × intermedia when in leaf, (privet) Ligustrum sp., Cotoneaster sp.|
|Supporting wildlife||Planting a mixture of species to extend flowering or fruiting periods, or using a range of plant species to provide a more diverse structure (and hence greater niche opportunities) may be of particular value||Hawthorn (Crataegus monogyna), beech (Fagus sylvatica), Rosa rugosa, Pyracantha cultivars, Ligustrum sp., yew (Taxus baccata)|
Tijana Blanusa, Principal Horticultural Scientist, at the RHS said:“In a world that is rapidly urbanising and where there is pressure on land use through the increased densification of cities, the relatively compact nature of the urban hedge may have a pivotal role in ensuring our cities remain ‘liveable’, through its various ecosystem benefits.”