docKnowledge - Greenroofing Info Sheet.indd
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Knowledge - Greenroofing Info Sheet.indd
BritishFlora Planting the seeds for a greener tomorrow BIODIVERSE GREENROOF INFORMATION BritishFloraare arespecialist specialistgrowers growersand andsuppliers suppliersofofUKUKNative Nativeand andlocal localprovenance provenancewildflowers wildflowers BritishFlora andseed. seed.We Wesupport supportthe thegreenroofing greenroofingindustry industryininproviding providingexpert expertecological ecologicaland andhorticultural horticultural and adviceononspecies speciesselection, selection,biodiversity biodiversityenhancement, enhancement,maintenance maintenanceand andestablishment establishmentofofplants plants advice greenroofenvironment. environment.We Wehave havea ateam teamofofskilled skilledlandscapers landscapersthat thatcan caninstall installthe thevegetation vegetation inina agreenroof biodiversegreenroofs greenroofsincluding includingplug plugplanting, planting,seeding, seeding,wildflower wildflowerand andsedum sedumblankets blanketsand and ononbiodiverse other substrate and wildlife features. 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The Thefollowing followingInformation Informationnote noteis isa abrief briefoutline outlineofof forforSustainable greenroofs focusingonon thevegetation vegetationsystem. system. greenroofs focusing the Benefits of Greenroofs x x x x x x Creates Ecological Habitats and Encourages Biodiversity Water Retention and Harvesting & Improved water quality Improves Air Quality Reduces Urban Heat Island Effect Creates Amenity Space & Wellbeing Financial Benefits- Aid to Planning Consent (BREEAM, CSH), Reduced Building Running Costs Grange Farm, Grange Road, Widmer End, Bucks, HP15 6AE T. 01494 718203 F. 01494 718989 www.britishflora.co.uk The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ [email protected] T: 01684 212027 F: 01684 578424 Registered in Cardiff No: 4376669 VAT No: 727 5996 79 www.britishflora.co.uk [email protected] Registration No. 8730825 VAT No. 178 1624 88 Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ BritishFlora Planting the seeds for a greener tomorrow Types of Greenroof; There are a number of different types of greenroofs and terms used to describe them including; Sedum roof, Extensive, Semi-intensive and Intensive, which are defined by substrate depth and the plant communities that can establish on these mediums. Intensive greenroofs are also known as rooftop gardens and can include anything from trees and shrubs to swimming pools and allotments. The ‘biodiverse’ or extensive roof is a shallow light weight system that can support a diverse assemblage of native wildflowers to create ecological habitats for wildlife. BritishFlora specialize in specifying and installing the vegetation layer for extensive/biodiverse and semi-intensive greenroofs. Weights and depths of substrates can vary and a suitably qualified greenroof designer and architect will need to be consulted on weight bearing loads of different roof designs. The Table below provides a guide to weight and depth of substrates in different greenroofing systems. Table.1. Comparison of different greenroof systems Sedum Roof Extensive/’Biodiverse’ Semi intensive Intensive/Rooftop Garden Vegetation Sedum spp. and Wildflowers & Grasses Grasses, Herbs & Herbs, Shrubs, mosses usually UK Native Shrubs Trees & vegetable plants specified growing Depth/Type of 20-60mm, 60-200mm, recycled 120-250mm 150-400mm. Substrate recycled crush crush brick, 10% Crushed brick, Light weight brick, 10% organic content 10% organic compost content organic content Substrate 10-60kg/m2 60-150 kg/m2 120-200 kg/m2 180-500 kg/m2 Low Periodic Periodic High Weight (saturated) Maintenance Greenroof Layer system Terrestrial vegetation requires adequate water, nutrients, drainage and air circulating around the roots to survive and this is recreated in the greenroofing layering system: 1. Seeds, plants or vegetation mat BritishFlora Planting the seeds for a greener tomorrow 2. 3. 4. 5. 6. Light weight substrate- porous and free draining Filter sheet to prevent blockage of drainage board Drainage and reservoir layer Moisture retention blanket Waterproof and root membrane Greenroof Design and Planning Fig.1. Greenroof Layer System A greenroof specialist and architect must be involved in designing a greenroof to calculate weight loading capacities and the appropriate greenroof layering system. BritishFlora works closely with greenroof designers to provide expert horticultural and ecological advice on native species planting, substrates and maintenance. An assessment of the prevailing conditions expected on the greenroof must be undertaken such as the prevailing wind direction, wind strength and shading to determine the vegetation suitable for the roof. There are seasonal constraints when establishing vegetation on a greenroof and therefore adequate planning is essential (see section on establishing vegetation below). UK Native Plant species for a ‘biodiverse’ roof The vegetation that will establish well in the dry, shallow soils and low nutrient environment on an extensive green roof are wildflowers and grasses that naturally occur in these harsh environments in the UK. These are the wildflowers, grasses and sedges of chalk/limestone, sandy soils and coastal grasslands, which are increasingly under threat in our natural habitats. The table at the end of this document is a recommended list of UK Native plants that are proven to establish well on extensive and semi-intensive greenroofs. The plant mix is biodiverse and can be adapted to encourage certain wildlife e.g. leguminaceae plant species such as red clover and kidney vetch provide valuable feeding for certain long-tongue bee species. The seed heads of yellow-wort or campion species provide overwintering for invertebrates and therefore provide valuable foraging potential for black redstart Biodiversity Action Plan species. Establishing vegetation on a greenroof Seeding Seeding is the least expensive way to vegetate a greenroof and is particularly recommended for large areas over 1500m2. There is a wider choice of species available from seed and the installation is relatively straightforward involving hand broadcasting or a mechanical spreader over larger areas. The roof can take up to 2 years before it looks established when using seed and most perennials will not flower until the second growing season. Substrates specifically designed for seeding are available that have a smaller particle size and higher organic content and depths should range between 50-150mm depending on the seed mix. Autumn sowing in August/September, depending on prevailing weather conditions, is recommended to ensure that seedlings will germinate in favorable conditions rather than be exposed to potentially hot and dry conditions of spring and summer. Irrigation of roof after seeding and lightly covering the seed can extend the potential sowing period. BritishFlora technical team can advise on the timing, seeding rates, substrates, and other materials needed to be added to the seed mix to ensure even and effective establishment of your green roof. The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ T: 01684 212027 F: 01684 578424 www.britishflora.co.uk [email protected] Registration No. 8730825 VAT No. 178 1624 88 Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ BritishFlora Planting the seeds for a greener tomorrow Plug planting Plug planting is an effective way of quickly establishing a greenroof and a wide range of species suitable for greenroofing are available in plug plants. Extensive light weight substrates between 80-150mm are suitable for wildflower plug plants, with some plants requiring deeper substrates than others (refer to plant species table at the end of the document). Ideally plug plants should be planted at the beginning of the growing season in March or April to allow a full growing season for the plants to establish. BritishFlora technical team can advise on planting densities, suitable substrates and additional growing materials than will ensure establishment of plug plants. Fig.3. 27cc greenroofing wildflower plug used in Fig.2. Planting wildflower plugs into greenroof substrate Sedum and wildflower blankets or pre-established systems A pre-established sedum or wildflower turf provides an instant green blanket effect and has the wow factor, especially when wildflowers are incorporated. This is the most expensive solution over larger areas and species mixes are limited to those grown on the blanket unless bespoke versions are grown to order. The weight of a wildflower blanket ranges from 35-44kg per m2 saturated weight versus 2-5kg per m2 for wildflower plugs so additional weight bearing needs to be considered. Daily irrigation of wildflower blankets during the establishment period is required and during subsequent extended dry spells to keep these blankets looking lush and green. Additional species can be added to a wildflower/sedum blanket by plug planting or over seeding into the blanket. Fig.4. Wildflower blanket BritishFlora Planting the seeds for a greener tomorrow Diverse substrate materials and depths A biodiverse roof should include a variety of substrate types and depths to increase the mosaic of habitat types, which in turn will encourage biodiversity and establishment of different plant communities. Ideally the extensive substrate depth should range between 50mm and 150mm to allow for different plant Fig.4. communities to blanket thrive, for example sedum will establish on the shallow Wildflower substrates and taller perennial such as field scabious will thrive on the deeper substrates up to 150mm. Diverse substrate materials and depths Biodiverse roofs aim to recreate brownfield sites, including habitat mosaics of bare ground, diverse vegetation and substrate types and low nutrient soil to allow less competitive wildflowers A roofhabitats should include a variety of substrate types and depths to and increase the mosaic of tobiodiverse thrive. These provide ideal foraging for invertebrates, birds mammal species. habitat types, which turn and will encourage and establishment of from different plant Sands mounds, gravel,instone wood piles biodiversity provide important wildlife refuges the harsh communities. Ideally the extensive substrate depth should range between 50mm and 150mm to environment on a green roof and burrowing habitat for invertebrate species such as mining bees, allow for different plant dwelling communities to thrive, for example sedumbe will establish on the loading shallow sand wasps and ground beetles. Substrate features should considered where substrates and taller perennial such as field scabious will thrive on the deeper substrates up to capacity allows on the building (discuss with architect/engineer). 150mm. Where wind erosion is a problem heavier substrates can be used effectively to weigh down the Biodiverse roofs aimand to allow recreate brownfield sites, habitat mosaics of bare ground, extensive substrate plants to establish by including creating sheltered areas behind stone piles. diverse vegetation and substrate types and low nutrient soil to allow less competitive wildflowers See Fig.5. below as an example of wind scouring remediation solution. to thrive. These habitats provide ideal foraging for invertebrates, birds and mammal species. Sands mounds, gravel, stone and wood piles provide important wildlife refuges from the harsh environment on a green roof and burrowing habitat for invertebrate species such as mining bees, sand wasps and ground dwelling beetles. Substrate features should be considered where loading capacity allows on the building (discuss with architect/engineer). Where wind erosion is a problem heavier substrates can be used effectively to weigh down the extensive substrate and allow plants to establish by creating sheltered areas behind stone piles. See Fig.5. below as an example of wind scouring remediation solution. Fig.5. Sand mounds and rockery areas on a greenroof Fig.5. Sand mounds and rockery areas on a greenroof The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ T: 01684 212027 F: 01684 578424 www.britishflora.co.uk [email protected] Registration No. 8730825 VAT No. 178 1624 88 Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ BritishFlora Planting the seeds for a greener tomorrow Maintenance Contrary to popular belief a biodiverse roof does require maintenance, especially during the establishment period (up to 3 months after planting). Irrigation is particularly important in the first 10 weeks and on roofs over 500m2 an automated sprinkler of leaky pipe system should be considered to maintain plant health. For plug plants irrigation is required every 4 days to once a week during the establishment period but wildflower blankets require daily irrigation during dry spells. Greenroofs are very nutrient poor environments and therefore slow release fertilizer should be applied at the beginning of the growing season to help plants establish. Additional maintenance tasks include removal of unwanted weeds and dead heading of perennials in the spring to allow for new growth. Old seeds heads should be left to overwinter to provide foraging potential for birds and overwintering sites for invertebrates. Cutting of wildflower turf and removal of this vegetation is required annually. BritishFlora can provide a full maintenance service to ensure your greenroof performs to expectations. Further reading Dunnett, N. P. & Kingsbury, N. (2008) Planting Green Roofs and Living Walls, 2nd edition. Timber Press, Portland, Oregon. Dunnett, N. P. & Kingsbury, N. (2004) Green Roofs and Living Walls. Timber Press, Portland, Oregon. GRO Greenroof Code (2011). The Greenroof Code of Best Practice for the UK 2011. The Greenroof Organisation (GRO) Technical Advisory Group. Gedge, D., Dunnett, N. & Grant, G. & Jones, R. (2006) Living Roofs. English Nature, Peterborough Snodgrass E, Snodgrass L (2006). Greenroof Plants. Timber Press, Portland, Oregon. The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ T: 01684 212027 F: 01684 578424 www.britishflora.co.uk [email protected] Registration No. 8730825 VAT No. 178 1624 88 Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ BritishFlora Planting the seeds for a greener tomorrow Table.2. Biodiverse UK Native Plant Mix for Greenroofing Plant Name Biting Stonecrop – Sedum acre Comments Succulent plant suitable for very dry shallow substrates. Yellow flowers. Can grow in very shallow substrate 10-100mm. Table.2. Biodiverse UK Native Plant Mix for Greenroofing Buck's Horn Plantain Suitable for windy and Plantago coronopus coastal sites Comments Plant Name Substrate depth of 50100mm. heads SucculentSeed plant suitable for Centaury – suitable foraging birds very dryfor shallow substrates. Centaurium erythraea Yellow flowers. Biting Stonecrop – Substrate depth of 50Sedum acre 100mm. Medium height Can grow in very shallow perennial substrate 10-100mm. Clustered bellflowerBuck's Horn Plantain Suitable for windy and Campanula glomerata Plantago coronopus coastal sites Prostrate/creeping Substrate depth of 50perennial. Substrate 100mm. Seed heads depth of 50-100mm. Good Centaury – suitable for foraging birds foraging for long tongues Common Bird'sfootCentaurium erythraea bee species including trefoil – Substrate depth of 50bumble bees Lotus corniculatus 100mm. Medium height Medium height perennial. perennial Common Cat’s Ear Substrate depth of 50Clustered bellflower100mm. Hypochaeris radicata Campanula glomerata 100-150mm Prostrate/creeping deeper substrate required, perennial. depth Substrate depth Common Knapweedmedium tall perennial of 50-100mm. Good Centaurea nigra foraging for long tongues Common Bird'sfootSubstrate depth including of 50bee species trefoil – 100mm. Annual from seed, bumble bees Lotus corniculatus colour in the first year Medium height perennial. Common Poppy Common Cat’s Ear Substrate depth of 50Papaver rhoeas 100mm. Hypochaeris radicata 100-150mm deeper substrate depth required, Common Knapweedmedium tall perennial Centaurea nigra Substrate depth of 50100mm. Annual from seed, colour in the first year Common Poppy Papaver rhoeas The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ T: 01684 212027 F: 01684 578424 www.britishflora.co.uk [email protected] Registration No. 8730825 VAT No. 178 1624 88 Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ BritishFlora Planting the seeds for a greener tomorrow Comments Comments Medium Medium perennial, perennial, blush blush red red throughout summer throughout summer Substrate Substrate depth depth of of 5050100mm. 100mm. Plant Plant Name Name Common Common Sorrel Sorrel –– Rumex Rumex acetosa acetosa Substrate Substrate depth depth of of 5050100mm. 100mm. Annual Annual to to grow grow from from seed seed provides provides colour colour in in first growing season first growing season Medium Medium height height perennial. perennial. Substrate depth Substrate depth of of 5050100mm. 100mm. Spring Spring flowering flowering CornflowerCornflowerCentaurea Centaurea cyanus cyanus Cowslip Cowslip -- Primula Primula veris veris Deeper Deeper 150mm 150mm Field Field Scabious Scabious –– Knautia Knautia arvensis arvensis 100100- Sedge Sedge of of dry dry grasslands. grasslands. Substrate Substrate depth depth of of 5050100mm 100mm Glaucous Glaucous sedgesedgeCarex Carex flacca flacca Herb-Robert -Herb-Robert Geranium robertianum Geranium robertianum Kidney Kidney vetchvetchAnthyllis Anthyllis vulneraria vulneraria Lady’s Bedstraw Lady’s Bedstraw Galium verum Galium verum substrate substrate Substrate Substrate depth depth of of 5050100mm. 100mm. Suitable Suitable for for shaded shaded and and exposed exposed areas areas Clump Clump forming forming prolific prolific self self seeder seeder suitable suitable for for all all biodiverse biodiverse roofs. roofs. Substrate Substrate depth of 50-100mm. depth of 50-100mm. Nectar Nectar sources sources bees bees and and butterflies butterflies (small (small blue) blue) Substrate Substrate depth depth of of 50-100m, 50-100m, medium to tall perennial, medium to tall perennial, slow slow growing growing -The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ T: 01684 212027 F: 01684 578424 www.britishflora.co.uk [email protected] Registration No. 8730825 VAT No. 178 1624 88 Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ BritishFlora Planting the seeds for a greener tomorrow Comments Substrate depth of 50100mm. Tall perennial, quick grower Plant Name Ox-eye Daisy – Leucanthemum vulgare Perforate St. John’swort – Hypericum perforatum Medium height perennial. Substrate depth of 50100mm. Seed heads good foraging resource for bird species Low growing perennial, nectar source for long tongued bee species including bumble bees Medium height perennial. Substrate depth of 50100mm. Red Clover – Trifolium pretense Ribwort Plantain – Plantago lanceolata Substrate depth of 50100mm, clump forming perennial. Very good nectar source and foraging Rock Rose – Helianthemum nummularium Rough Hawkbit Leontodon hispidus - Medium height perennial. Substrate depth of 50100mm. Medium height perennial. Substrate depth of 50100mm. Very drought tolerant. Salad Burnet – Sanguisorba minor Medium height perennial. Substrate depth of 50100mm. Very good nectar source for inverts. Small Scabious Scabiosa columbaria The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ T: 01684 212027 F: 01684 578424 www.britishflora.co.uk [email protected] Registration No. 8730825 VAT No. 178 1624 88 Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ BritishFlora Planting the seeds for a greener tomorrow Plant Name Comments Suitable for windy sites and those near the sea. 50100mm substrate Thrift- Armeria maritima spp maritima Thyme – Thymus polytrichus Mat forming aromatic perennial. Good for high foot traffic areas and shallow substrates under 50mm Tall biennial, deeper substrates 100-150mm. Good nectar resource for inverts, good potential foraging habitat Viper's Bugloss – Echium vulgare White Campion - Silene latifolia/alba Medium height perennial. Substrate depth of 50100mm. Resource for foraging moths and night flying inverts and therefore attracts bats. Succulent plant suitable for very dry shallow substrates. White flowers. White Stonecrop – Sedum alba Wild Basil – Clinopodium vulgare Wild Carrot – Daucus carota Wild marjoram – Origanum vulgare Substrate depth of 50100mm. Aromatic small perennial. Attracts foraging moths and therefore bats Medium height perennial, deeper substrates 100150mm. Substrate depth of 50100mm. Attracts foraging moths and therefore bats The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ T: 01684 212027 F: 01684 578424 www.britishflora.co.uk [email protected] Registration No. 8730825 VAT No. 178 1624 88 Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ BritishFlora Planting the seeds for a greener tomorrow Plant Name Wild Pansy/Heartsease - Viola tricolor Comments Small perennial, requires substrate depth of 50100mm. Extended flowering period Substrate 100mm depth of 50- YarrowAchillea millefolium Medium height perennial. Substrate depth of 50100mm. Yellow toadflax – Linaria vulgaris Yellow-wortBlackstonia perfoliata Substrate depth of 50100mm. Suitable foraging for black redstarts, invertebrates overwinter in seed heads The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ T: 01684 212027 F: 01684 578424 www.britishflora.co.uk [email protected] Registration No. 8730825 VAT No. 178 1624 88 Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ
