Putting the ‘Green’ into Green Infrastructure: Maximising Hedges’ Potential for Urban Restoration

The problem – why do we need this research?

Past research, including RHS-led work (Blanusa et al., 2019), established that urban hedges can play a positive role in delivering multiple environmental benefits.

However, most hedges are grown from single plant varieties which could generate a homogenised cityscape and have negative implications for biodiversity, and pest and diseases resistance.

There are also practical barriers to wider uptake, for example in school settings in urban areas where they could bring considerable benefits, because of concerns around the safety, cost and time needed for plant management. 

What are we doing?

Two key components of this project are:

  1. research into the required plant structural and functional traits for the delivery of multiple environmental benefits of mixed hedging
  2. a school ‘case study’ testing a science-driven solution in practice, in order to capture the environmental and social benefits of diverse planting, while addressing the practical concerns in implementation and maintenance
We will further link the research and school case-study through a ‘living lab’-type demonstration at RHS Garden Wisley, where the engaging, publicly-accessible interpretation will showcase examples of best practice which passed both the research and practical criteria.

What difference will this research make?

This research will provide us with data to compare performance of hedge monocultures vs mixes in terms of year-round potential to reduce rainfall run-off and localised flooding risks.

It will also investigate hedges' capacity to improve air quality, along with establishing practical hedge-management protocols which would work in settings such as school grounds.

Knowing which planting combinations to choose to get the most environmental benefit, and how to look after them effectively, could enable wider uptake of this cheap and popular form of green infrastructure which requires relatively little ground footprint.

The project is now complete and findings will be demonstrated at RHS Chelsea Flower Show 2024. Download a summary of key results (5MB pdf)

Further information

Blanusa, T., Garratt, M., Cathcart-James, M., Hunt, L., & Cameron, R. W. (2019). Urban hedges: A review of plant species and cultivars for ecosystem service delivery in north-west Europe. Urban Forestry & Urban Greening, 44, 126391.

Funded by the Royal Commission for the Exhibition of 1851.

Our current advice

Hedges: choices with environmental benefits
All about hedges: the environmental benefits they provide and their role in promoting biodiversity (5MB pdf)

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.