Why is no-one sciencing urban road verges?

Those people who work high up in the hotel chain business will know that a refurbishment of a hotel is important not just for what it looks like but also for how long it takes to clean. Ongoing maintenance costs are frequently what makes or breaks a business. To this end then for each proposed refit style a model room is built, the cleaning of which is timed and this information can then be used to work out future hotel running costs – the larger the hotel chain the more important small savings in time per room become; small savings make a big difference on a large scale.


Here yellow-flowered common bird’s-foot-trefoil grows on a mown verge near the Tees Barrage. The area used to be industrial and so it is likely to be growing in a thin layer of topsoil over free-draining calcareous slag (historic waste from the local iron-making industry).

We should apply these same principles to the public land that local councils manage in our urban and sub-urban areas. In particular I’m concerned with the grassy regularly-mown road verges where there is that same balance needed between visual appeal and cost of maintenance. Unfortunately, I can find no scientific vegetation community trials that investigate how different plant communities (both native and novel) might look on road verges, how much environmental benefit they might bring, how much it would cost to maintain them. Yes, there is information on how to make a meadow…but meadows require long grass to be removed from site at the end of the year and that is not always practical or the cheaper option.


White clover flowering in abundance on a mown roundabout in early July, with the yellow of common bird’s-foot-trefoil by the path at the back of the photo.

Would it, for example, be possible to have a plant community of common bird’s-foot-trefoil, selfheal, white clover, red fescue, etc. by the sides and in the middle of a dual carriageway or motorway and perhaps just cut it once or twice a year? All plants grow low and would not affect sight-lines, are reasonably salt-tolerant, tough growers, cope with drought, and are more beneficial to some pollinators than just ryegrass. Perhaps we can think of the bird’s-foot-trefoil flowering over a set period, much as daffodils are used to decorate road verges in the spring, and then returning to mown green vegetation? Can it all be applied retrospectively by changing the soil and the plants just like town centre paving is changed to refresh the shopping area? Should it be intrinsic in any new road building or widening as part of the third dimension of sustainable development? – see guidance by UK Gov since 2012. What about new housing estates? Could the soil infill be specified as free-draining low-nutrient soil (or clay sub-soil if that’s locally appropriate) so everything grows lower and more slowly, rather than the standard infill of top soil over-sown with superquick germinating rye-grass?


Detail of selfheal, common bird’s-foot-trefoil, and the leaves of autumn hawkbit on the suburban road verge below in early June.


A relic plant community from when the road was created through farmland in the 1970’s or 80’s (can’t find a definitive date) as an entrance to a large housing estate,Hemlington, Middlesbrough. The roundish patch of grey-green colour is glaucous sedge.

And then what effect do different mowing regimes have on existing road verge vegetation? If we change the regime can we get wildflowers looking good straight away without any need to add new seeds? This is an issue at one of my local councils and one of the reasons why I started looking for information. They have looked into leaving the grass long then cutting and removing the grass like a hay meadow would be managed, but the removing of the hay is too expensive and problematic to dispose of: What they need is a compromise between short mown grass and long meadow flowers – a compromise that is relevant to the socio-economic constraints of the area. In places common bird’s-foot-trefoil and self-heal are already present, perhaps the remnants of semi-natural pasture disrupted when the housing estates were built. They’ve been mown regularly for 40 odd years with the cuttings left on top of them all the time and are still there. What if we leave them to flower and seed and then cut? Do they increase? Decline? Will the cut vegetation be too long and smother regrowth if left to decay naturally? What is best for pollinators? Cut a patch in May to delay flowering but leave a patch to flower normally? Alternate cutting so different patches flower at different times? How big a patch is best for pollinators? Or do we just raise the mower blades and does that allow flowering? How high? So many questions…and I can’t find any UK science on the internet that has properly investigated them…



Daisies at Linthorpe Cemetery, Middlesbrough, flowering at the end of May.



*after publishing this blog it turns out someone is sciencing urban road verges for a PhD – article here http://www.sheffieldnewsroom.co.uk/living-highways/  and the lead researcher is Olivia Richardson @orichardson12 and they are using #livinghighways to discuss the project. See also http://www.wildsheffield.com/LivingHighways   *

*A really interesting just-published open-access paper suggested by Helen Hoyle @hehoyle1 and who is the lead author giving the point of view of the people in the council who manage the land and also people who live nearby  http://www.sciencedirect.com/science/article/pii/S1618866716305489 *

When I asked the Urban pollinator project ( @ReadingUrbPolls) they kindly suggested this paper as a start http://www.sciencedirect.com/science/article/pii/S0301479716310556  and it is a summary of urban road verges in relation to biodiversity and cost-effective management.

This study suggested by Dr Manu Saunders ( @ManuSaunders on Twitter) stresses the need for rotating areas of cutting in relation to preserving insects on sea wall grassland in the UK https://www.researchgate.net/publication/267644487_How_does_mowing_of_grassland_on_sea_wall_flood_defences_affect_insect_assemblages_in_Eastern_England

There has been a study on timing of grass cutting in a UK park  – paper here https://www.researchgate.net/publication/264461061_Public_approval_plus_more_wildlife_Twin_benefits_of_reduced_mowing_of_amenity_grass_in_a_suburban_public_park_in_Saltdean_UK and article with pics here https://phys.org/news/2014-09-unmown-win-win-wildlife-humans.html where it looks like the park was already unimproved grassland frankly, but I think they still create the long grass of a meadow rather than a lower growing plant community.

The subject seems to be discussed in ‘Environmental Horticulture: Science and Management of Green Landscapes’ by Ross Cameron and James Hitchmough where they give some suggested plants but I don’t have a copy the book and from what I can see of it on the internet their list of references doesn’t appear to give any UK urban examples.

On a more domestic scale, this website has examples of flowering lawns without using grass http://www.grassfreelawns.co.uk/  and has derived from a PhD study, and seems a step in the right mental direction but too labour intensive for extensive urban areas.

There is a project on Lawns happening in Sweden “Lawn as ecological and cultural phenomenon: Search for sustainable lawns in Sweden”  http://www.slu.se/en/departments/urban-rural-development/research/landscape-architecture/projects/lawn/

The UK Plantlife campaign is concerned with rural road verges see http://plantlife.love-wildflowers.org.uk/roadvergecampaign and their .pdf on the subject http://www.plantlife.org.uk/uk/our-work/publications/good-verge-guide-different-approach-managing-our-waysides-and-verges references a paper on the effect of cutting on rural road verges – the results of an experiment spanning 1965 to 1982; a summary is here http://www.conservationevidence.com/individual-study/670 .

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2 Responses to Why is no-one sciencing urban road verges?

  1. Jim Stephens says:

    I have a 1993 book called The Wildflower Handbook, published by The Department of Transport, which deals with some of the issues you raise. One point stands out; all the rooms in your hotel will be identical, all the verges will be different. Soil, aspect, fertility and so on make a standardised treatment, both at creation and for subsequent maintenance, very difficult.
    Verges have never been more important as wildflower habitat. Farmland is a wildflower desert, moorland is usually too acid and has supported sheep for too long to be of much value, many areas like the scarp of the North Downs which used to be open grassland have for want of maintenance become semi-wooded. Gardens are generally small and fragmented.
    Well managed verges have the potential to be a large scale, connected network much of which is, by virtue of its location, undisturbed.
    There is still resistance, especially in urban areas, to verges being left uncut. Many still see them as weedy, untidy and indicative of neglect. If you’re talking about brambles, docks and cow parsley which when cut leaves a swirl of chopped up litter blowing about, they have a point.

    • Martin says:

      Thank you for the comments Jim. I didn’t know about that handbook – I’ll give it a read as I think it is here as a .pdf to download http://www.standardsforhighways.co.uk/ha/standards/dmrb/vol10/section3/ha6793.pdf .
      You are quite right about the hotel rooms being identical and the verges different and that’s a point I missed. However, I think there will be a common set of plants present though, much in the same way as the national vegetation classifications work and then I would like to see regional variation in species. Similarly a standardised core treatment has to be possible in urban areas because really all that will be changed is the timing of the mowing or the height of the blades (or at least that is my thinking so far on what evidence I’ve seen, but we’ll see).
      I agree with the importance of verges as wildflower habitat; in my area we have a Local wildlife Site designation for road verges, as do many other areas. I’d also like to see greater appreciation of them as ancient grassland too.
      Litter…many areas where I am are standard trees and mown grass – the shrubs were taken out because “the litter catches on them and it looks awful” …Litter is such a problem and I wish there were an easy answer.

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