Verges as wildlife habitat
Grassland road verges represent a habitat that has suffered a devastating decline over the last century. 97% of traditional wildflower meadows have disappeared in Britain so the plants and animals that rely on this habitat have very few places left where they can thrive. Road verges, if appropriately managed, can help to reverse this trend and make an important contribution to supporting local biodiversity.
Regularly mown verges offer very little to wildlife. Few plants are able to flower so there is little food for nectar-feeding insects such as bees and butterflies. The exposed ground dries out creating a very inhospitable environment for most invertebrates. Without these creatures the food chain collapses so there are fewer birds and mammals such as hedgehogs.
The answer is simple, allow the grassland verge to grow. Taller vegetation offers cover, feeding opportunities and a range of micro-habitats that are not available in regularly mown grass. In addition, many more plants can flower and offer nectar to pollinators such as bees and butterflies. Even an unmown grassland without flowers offers excellent wildlife habitat.
In general, the more species of grasses and wildflowers that grow in the verge, the better it is for wildlife. Many insect species are specialised to feed on just one or two types of plant so the more diverse the flora the more wildlife it supports. The verge surveys have shown that in most cases there is a surprisingly diverse flora already present. By simply allowing the verge flora to grow during the Spring and Summer they will produce a valuable wildlife-rich grassland habitat.
Mowing regime
The simplest and most important action is to stop mowing between April and August. This allows the grassland to grow, flower and set seed, providing excellent wildlife habit. A narrow strip alongside the carriageway (or footpath) can remain regularly mown as this prevents longer vegetation falling onto the road/path, it also helps to 'frame' the meadow and lets people passing know that the verge is uncut by intent and not neglect!
In late August, or preferably early September, it should then be cut short and the cuttings removed. The cuttings can be left for a few days to dry and drop any remaining seeds but this isn't necessary so late in the year as most seeds have already been dispersed.
Many mowing machines will struggle to cut long vegetation so a strimmer or a reciprocating blade mower is probably needed. Traditionally meadows were cut by hand with a scythe so this could be an option if anyone is keen to learn this skill.
Whilst an annual cut will help the plant diversity it does deprive other wildlife of important cover and over-wintering sites. The ideal solution is therefore to only cut part of the verge each year leaving part as tall vegetation, then alternating the areas the following year.
If your verge is particularly nutrient-rich and dominated by just a few large grasses and wildflowers, an option is to cut and collect the mowings three times during the first year. This will help make a significant dent in the nutrient level and allow a great variety of wildflowers and grasses to flourish in year 2 and onwards.
Removing the cuttings
The second most important action is to remove the cuttings. This is vital to prevent the build up of a mat of dried stems which will smother the smaller plants and crucially to prevent enrichment the soil as the cuttings gradually decompose - the opposite of what we want!
The types of plants growing on the verge are largely determined by the soil. Most verges are rich in nutrients, particular nitrogen, which allows large plants such as Cow Parsley, Nettle, Docks and False Oat-grass to dominate. Whilst these species do support a lot of wildlife, they also out-compete the smaller species leading to a reduced floral diversity overall. By removing the cuttings the soil fertility will gradually fall and a wider range of flower and grass species will naturally develop over several years.
Disposing of the cut vegetation can be a challenge. Once dry it is effectively hay so is ideal food and bedding for horses, rabbits and other pets. Local residents with these animals may be keen to collect the hay from the verge, especially if raked into a convenient pile. Failing this it can be composted simply by piling it into a heap. It is unlikely that the verge itself will be suitable for this so it is probably necessary to find a suitable site nearby. The cuttings can also be taken to your nearest Waste and Recycling Site for treatment as ‘green waste’.
Note: if the verge contains Ragwort, it may be worth hand-pulling these before cutting if the hay is to be used as animal feed or bedding.
To seed or not to seed?
Whilst it may be possible to add more floral diversity through seeding and/or plug planting, this is an expensive and labour-intensive process that is not guaranteed to work and not generally recommended. Most species introduced artificially tend not to thrive and many disappear within 2-3 years. The most cost effective, sustainable and generally most successful way to improve grassland habitat for wildlife is simply to change the mowing regime to 'cut and collect' and let nature do the rest.
It is generally best to work with nature and manage the verge as it is. Surveys have shown that most verges are surprisingly rich in species and these just need the chance the grow and flower. 'Chocolate box' wildflower meadows, as portrayed by seed companies, are unlikely to be sustainable on the nutrient-rich soils that most verges have, but over time most meadow grasslands that are managed correctly will become more species diverse naturally. Remember that for most wildlife, it is the taller vegetation that is important, not how colourful it is.
If seeding is desirable, care should be taken to source the seed from a reputable source with a mix of native wildflowers and grasses suitable for the soil. Emorsgate Seed's EM2 meadow mix (4g per sq metre) is one suggestion.
It can be tempting to introduce colourful annuals such as Poppies, Corn Marigold and Corncockle. However, these are annual species which typically grow on arable land after ploughing. They are not a natural component of grassland meadows and will, in any case, largely disappear after flowering in year one so are generally not worth the investment.
If seeding is to go ahead, prepare the ground first. The verge should be mown, then scarified (partially disturbed to expose some bare soil). This can be done by vigorous raking. However, it is usually best to only seed a few areas of the verge. This is cheaper, requires less effort to prepare the ground and will enable successful plants to spread naturally. Chemical herbicides should not be used. Seeding should take place in Autumn as many seeds require the cold chill of winter to mature ready for germination in the Spring.
Yellow Rattle is generally a desirable species in grassland meadows as it parasitises grasses so they weaken and become less dominant, leaving space for more wildflowers. This species isn’t included in most seed mixes so is best obtained separately. Preferably, harvest the seed locally if there is a known population and the land-owner agrees. Yellow Rattle needs to be sown fresh in Autumn as it needs cold exposure to germinate. It doesn’t usually do well as a plug plant because it needs grasses to feed on as it grows. Prepare the ground as described above.
Green Hay is another option and a much better way of adding more plant diversity. If there is a quality hay meadow near to you, ask the farmer/land-owner if you can have a small quantity of the cuttings before being dried and baled. These cuttings will contain seed from the meadow plants which will be dropped as the vegetation dries out. Thinly spreading the ‘green’ hay on your verge should add seed with local genetic provenance – far preferable to buying seed from a commercial supplier where the genetic varieties included are not usually local.
An alternative to seeding is to plant ‘plugs’ of pre-grown wildflower seedlings into a small bare area of the verge in Spring. This can be easier and more effective than sowing seed. Black Knapweed, Lady’s Bedstraw, Meadow Buttercup, Bulbous Buttercup, Ox-eye Daisy, Meadow Cranesbill and Bird’s-foot Trefoil are all relatively easy to establish as plug plants and in general are likely (but not guaranteed) to cope with the competition of the existing plants. Growing such plug plants from seed can also be a good way of getting the community involved.
Note - there are hardly any native meadow species that grow from bulbs and it is generally not appropriate to plant any bulbs in the verges. Daffodils, Hyacinths and the like are garden plants and do not have a place in a wildflower meadow.