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Wild flower seeding

The use of wild flower seed is increasingly popular, but it is important to get it right so that it survives but does not threaten biodiversity.
In these times of budget squeezes and paucity of grant opportunities, there is a quiet revolution in planting. Many plant specifiers are turning to wild flower seeding as an alternative to costly traditional ground cover such as annual bedding or shrubs. Good intentions of improving biodiversity are also part of the equation. This has resulted in the development of the wonderful planting styles championed by, amongst others, Nigel Dunnett in Sheffield with new techniques for green roofs, rain gardens, prairie planting and pictorial meadows.

But alarm bells are ringing among specialists in the conservation of wild plants. Britain’s wild flowers are already struggling against continuing and significant changes brought about by habitat loss and fragmentation, climate change and pollution. Wild flower seed can bring lost colour back to places where it cannot hope to return of its own accord but, in the wrong places, it can be counterproductive, bringing yet another pressure to bear on wild flower populations that need sympathetic and supportive management to survive. Of a total of 1,346 wild plant species in Britain, 45 are classed as Critically Endangered, 101 species as Endangered, and 307 species are listed as Vulnerable. In other words, there is conservation concern that a third of our plants are edging towards extinction. In response to this, Plantlife has produced seeding principles to help to address issues facing our native plants. 

Seeding in the wrong places
It would be surprising to find anyone releasing flocks of declining birds or threatened mammals into the countryside without rigorous checks and controls. Yet there is often widespread and unchecked acceptance of wild flower seed mixes, often including plants of non-native origin. Our native plants are both resilient and opportunistic; give them a chance and they will move naturally around the landscape, appearing spontaneously when least expected, or springing up from the seedbank like buried treasure. For example, after reconfiguration of a road junction at Duxford, Cambridgeshire in 2004, a verge was reinstated but intentionally without seeding. The site naturally came up with a great floral display including rough and common poppy and common fumitory.

In many inner urban areas the seed bank has been suppressed for so long that there is insufficient latent seed for natural regeneration to be successful, but in the countryside, suburban areas and remnant rural areas within towns, allowing the dormant seed bank to do its thing is a good solution. 

Legislation is at last bringing some protection here. For example the Wildlife and Natural Environment (Scotland) Act 2011 has made it illegal to plant non-native species in wild areas, which means that only native wild flowers may be used in planting schemes in all areas classified as the ‘wild’. Definitions of the wild and other clarifications can be found in the Scottish Government’s Code of Practice. In England and Wales there is not as yet any equivalent legislation.

Plantlife seeding principles
Think good management first Experience tells us that the most sustainable and cost-effective way to revitalise our countryside and naturalistic open spaces is to manage them correctly, so safeguarding the distinctiveness of local flora. Some commercial wild flower material only carries small proportions of the genetic diversity in native plant populations. With no requirement to meet high quality standards, irresponsible suppliers are producing and selling low-quality wild flower seed.


Green hay method
Cumbria Wildlife Trust through its ‘Meadow Life’ project has used the green hay method to increase the native plant diversity of Carsa Brow, a community parkland site around seven miles from the donor site, an SSSI hay meadow (Piper Hole) which is Cumbria’s Plantlife Coronation Meadow. Carsa Brow was a grassland with suitably low nutrient levels that had limited existing botanical interest and was judged a suitable candidate to be diversified by the addition of green hay. Carsa Brow was power harrowed in preparation to receive the green hay dressing to create suitable open ground for seeding. The hay was cut at Piper Hole on July 27th 2013 and immediately transported to Carsa Brow to prevent it over-heating or shedding seed. It was then spread by a volunteer work party. There are plans for further work at the site to grow and plant wildflower plugs from seed collected this summer from nearby verges, involving children from the local school.


Native and non-native
The verge at this road junction adjacent to a rural area of Scotland (above) has been recently sown with a mixture of native and non-native plants, which is in contravention of legislation. If seeding is chosen as a solution, then the photo at Broxden roundabout in Perth (below), demonstrates that use of non-native species is unnecessary. Native species alone give a glorious display. Even in this case, natural regeneration would have been possible from the seed bank and a better solution for local biodiversity, but nevertheless the native species used here have raised public awareness and appreciation of native plants.


A checklist of effective habitat management actions
• At design stage, assess existing wildlife value and restoration potential of your site as an integral part of project planning. Simple changes to land management can lead to wild flowers appearing. Natural regeneration and spread takes longer but results are far more sustainable and cost-effective.   
• Help seeds move around the landscape by linking sites as part of restoring ecological networks.
• Ensure your contract incorporates the longest possible aftercare period, in order to specify appropriate maintenance techniques. 

Where not to sow
• Avoid sowing wild flower mixes in the wider countryside or adjacent to existing natural or semi-natural habitats or Sites of Special Scientific Interest (SSSIs) where there is a good chance regeneration can take place naturally.
• Always avoid introducing seeds or plants to existing species-rich habitats or those of high conservation value, except in extreme circumstances as part of a rare plant rescue project.

Sow smart! 
• At urban sites with no realistic hope of natural colonisation we recommend either:
(a) sowing basic mixes of approximately five colourful, universal species of local provenance, such as oxeye daisy and yellow rattle. Choose mixtures according to geology and region. Don’t attempt to replicate complete national vegetation types – less is more. Over time, additional species will appear, allowing more natural development of species-rich vegetation;
(b) using the green hay method (or wild harvested seed for woodlands) from local sites which lie on similar soils/geology.

• For help selecting species in England and Wales contact the National Wildflower Centre. In Scotland contact Scotia Seeds.
• In specifications or bills of quantities, stipulate that seed sources and mixes must be as local as possible and be approved by the landscape architect. Consider using named suppliers. 
• Check the labelling of seed delivered to site. Ask for proof from contractors that seeds fit the specification.
• For fertile sites and those containing aggressive grass species such as perennial rye grass (Lolium perenne), consider broadcasting approximately 1g/per m2 of yellow rattle (Rhinanthus minor), which is hemi-parasitic on grasses, thereby reducing grass vigour and creating space for wild flowers to arrive more readily. Check with the contractor or supplier that seed is of local provenance. Six subspecies of yellow rattle occur across Britain, reflecting differing geologies and habitats, so it would be tragic if we upset this balance through introduction of non-native stock from the continent.
• Provide the right ecological conditions for long-term survival of vegetation being created. Thin, nutrient-poor soils typically re-establish as species-rich vegetation more satisfactorily than do nutrient-rich soils. Management, such as grazing or mowing, is likely to be necessary to ensure that plant communities retain their species-rich characteristic.
• Avoid non-native plants where possible – a small percentage are aggressively invasive, whilst others can compromise the scientific interest of natural vegetation types. See our invasive non-native plant pages on our website for more information.
• Limit use of annual cornfield mixes unless you are certain that the annual management required for this will continue. If not, use perennial mixes. Though providing a hit of colour and pollen, annual seed mixes are the equivalent of a fizzy energy drink, rather than a balanced diet for long-term habitat health.
• If schools and community groups wish to use seed bombs, encourage them to make their own using locally collected seeds, or seeds acquired from local, reputable suppliers. Only throw them in urban areas or gardens. Seed bombs should not be used in the wild.
• If possible, document and monitor carefully any attempts to restore habitats keeping note of any species sown, enabling you and others to distinguish between new native colonists and sown introductions. Share findings with Plantlife; often such initiatives are poorly documented and can
remain unmonitored.

Plantlife and BREEAM
BREEAM offers a useful framework for a plant conservation focus on planting design in urban and rural areas. In SUDS schemes or rain gardens, when the areas in question are near to water courses, in rural areas and where sites are adjacent to valuable habitats, Plantlife suggests that native locally sourced plants should be specified to maintain the local distinctiveness of native plant communities.

In terms of roof gardens, and if the development is in an urban area, Plantlife acknowledges that some non-native species, including some sedums and alongside native species, are easier to establish and more durable in the potentially harsh environment of a roof garden. Consider including some native plants however to support a wide range of pollinators.

Matilda Scharsach works for Plantlife Scotland,
the Scottish branch of the international wild plant conservation charity based in Salisbury.  
Recommended reading

Plantlife Seeding Principles
www.plantlife.org.uk
These can be found by following the ‘Keeping the Wild in Wild Flower’ links
on the Scotland pages under ‘campaigns’.

Plantlife Road Verge Campaign
Flowers on the Edge
www.plantlife.org.uk
This can be found by clicking on Road Verge Campaign in ‘campaigns’ on the main Plantlife homepage.

Scottish Government
Non-native Species Code of Practice
www.scotland.gov.uk/Publications/2012/08/7367/5 seeds, or seeds acquired from local, reputable suppliers. Only throw them in urban areas or gardens. Seed bombs should not be used in the wild.
• If possible, document and monitor carefully any attempts to restore habitats keeping note of any species sown, enabling you and others to distinguish between new native colonists and sown introductions. Share findings with Plantlife; often such initiatives are poorly documented and can remain unmonitored. 

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Comments

Posted by Jack Mulligan - August 5th, 2016
I hadn't thought about the difference between using native or non-native plants in my flower beds. I love wild flowers, but mine always die. I should probably make sure I'm getting native flowers that can handle the climate. http://www.vermontwildflowerfarm.com/wildflower-seed-wildflower-mixes.html

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