Living roofs

Front cover photographs:Main shot: A meadow on a shed.James FarrellTop left: Thyme growing on an urbanliving roof. Nigel DunnettBottom left: Blue butterflyPolyommatus icarus. RogerKey/English Nature

English Nature, the Rural DevelopmentService, and the Countryside Agency.Working in partnership to conserve andenhance our landscapes and naturalenvironment, to promote countryside access and recreation as well as publicwell-being, now and for future generations.

This is one of a range of publicationspublished by:External Relations Team English NatureNorthminster HousePeterborough PE1 IUA

www.english-nature.org.uk

© English Nature 2006

Printed on Evolution Satin, 75% recycled post-consumer waste paper, elementalchlorine free.

ISBN 1 85716 934.4

Catalogue code IN 18.5

Text by Dusty Gedge, with Nigel Dunnet,Gary Grant and Richard Jones

Designed and printed byAstron Document Services, 8M.

Working towards Natural Englandfor people, places and nature

Some greenery will naturally growon most roofs. Many roofs are hometo some very rare moss and lichenspecies, especially in areas of lowpollution. However, in this bookletthe term ‘living roof’ (or ‘greenroof’) is used to describe a roof thathas been intentionally covered invegetation. These are now verycommon in countries such asGermany and Switzerland, wherethey can be found on all sorts ofbuildings, from factories, hospitalsand schools to offices and housingdevelopments. But it’s not just largebuildings that are suitable for thistreatment: there are manyopportunities to create living roofs onand around the house and garden –on sheds, porches, outhouses,balconies, garages and smallextensions. Even in the inner city,the roofs on housing estates, multiplegarages, litterbin sheds and balconiesall have the potential to be greened.

The plants suitable for living roofsare not necessarily those found in atraditional English garden, but theycan help create habitats that will

3Living roofs

A few pot plants can help to green-up a roof. Dusty Gedge/Livingroofs.org

2

Living roofsIf you can see any roofs from

your house or office, the chances

are that they are fairly lifeless

and unappealing – perhaps made

of bitumen or asphalt. But roofs

don’t have to be dull and dead.

With effort and imagination, we

could change these sterile

surfaces into green oases. These

would not only provide a haven

for wildlife but also transform

the view from upstairs windows!

attract some very interesting andunusual wildlife.

This leaflet provides some guidance onhow you can make a living roof.However, it is only an outline andcannot take the place of expert advicefrom relevant professionals such asstructural engineers, roofing contractorsand suppliers.

The case for living roofs

Living roofs are not just good forwildlife: they make a positivecontribution to the environment in anumber of other ways.

• They help to cool the room below in hot weather. Conversely, in winter a living roof can provide insulation.

• Living roofs act as sponges, retaining water before allowing it to

Even Portakabins can be given living roofs. ZinCo GmbH

A living roof on a Norwegian boathouse. Roger Key/English Nature

5Living roofs4

evaporate into the atmosphere. Inheavy rainfall, this can reduce the likelihood of local floods and this is one of the main reasons living roofs are now a legal requirement in Germany.

• They protect a roof’s waterproofing from the effects of ultra-violet light and the weather, especially frost. This means that the roof is less likely to leak.

Types of living roof

Living roofs can vary greatly in theirappearance and character. They canbe designed to support low-growingmosses and sedums, wildflowers andgrasses and even shrubs and trees.Everything depends on the type ofroof in question.

There are three basic types: extensive,semi-extensive (also known as semi-intensive), and intensive. These termsrelate to:

• the amount and kind of maintenance that each type may require;

• the depth of soil (more usually referred to as ‘growing medium’or ‘substrate’) which may either be natural or manufactured; and

• the type of plants the area will support.

Extensive living roofs These are the most lightweight andeasily-maintained living roofs and aretherefore also the most common.They are made using shallow soils,which often dry out. This factor,combined with wind and frostexposure, creates a very harshenvironment for plants. To cope withthese conditions, any plant living hereneeds to be tough, hardy and drought-tolerant. These are generally speciesthat, in the wild, grow in coastal, cliff,mountain and dry meadow habitats.

Extensive living roofs tend to have arelatively low weight and are thus themost suitable choice for structuressuch as sheds, garages and smallextensions.

Advantages:• Light weight: 80 – 120 kg/m2.• Shallow soils: depths between

20 mm and 100 mm.• Can withstand harsh weather

conditions (especially lack of water).

• The drought-tolerant conditions are good for a range of species often under pressure in the wild.

• Very low maintenance.

But there are also somedisadvantages:

• The most lightweight and shallow living roofs will support only a small range of vegetation.

• Simple living roofs may have limited visual appeal.

• Shallow, extensive living roofs can be very susceptible to severe drought, leading to die back and patchiness.

Semi-extensive living roofsAlso known as ‘semi-intensive’,these roofs have deeper soils and cansupport both a greater number and awider diversity of plants, makingthem more decorative. However,their depth makes them heavy andthey need a relatively strong structureto support them. Semi-extensiveliving roofs combine some of thelow-maintenance and low-inputbenefits of extensive roofs –especially if naturalistic plantings areused. Some types, though, areeffectively small gardens in their ownright and need to be tended in thesame way, including regular weedingand watering.

A living roof in Canary Wharf. Dusty Gedge/Livingroofs.org

Additional supports allow this shed to bear the weight of asemi-extensive roof. Nigel Dunnet

7Living roofs6

Advantages:

• Can support a wider range of plants and other associated wildlife.

• More decorative than extensive roofs – have a longer flowering season.

• Require less water and other inputs, such as fertilisers.

Disadvantages:

• Need a strong structure to support them.

• Additional maintenance is required – the greater depth of substrate also encourages unwanted plants to grow there.

Intensive living roofsIntensive living roofs are a thirddistinct type, but not one consideredhere. These roofs have very deep

substrates, allowing the growth oflawns, shrubs and even trees. Theyare therefore impracticable in almostall domestic situations.

Which roofs are suitable?

Flat roofs lend themselves mostreadily to being ‘greened’. It is alsopossible to green other types such aspitched, barrel and domed roofs. Inthese cases, however, restraints areneeded to ensure that the growingmedium does not slide off. Roofswith very steep slopes are clearly notsuitable!

Garages • Garages with tiled or corrugated

roofing may not be able to have a

full living roof. The structure may need to be assessed. However, encouraging moss on the roof will provide habitats for invertebrates and feeding areas for birds such as blackbirds.

• Garages with flat asphalt roofs should be able to support a lightweight living roof such as a sedum blanket or, if a concrete deck has been used, a deeper substrate-based, extensive living roof that can be used to grow wildflowers.

Sheds• As sheds are generally very

lightweight structures, even putting on a sedum blanket may be inadvisable without some

Living roof type Soil or substrate depth Planting possibilities

Extensive 0–5 cm Simple sedum/moss communities.

5–10 cm Short wildflower meadows. Low-growing, drought-tolerant perennials, grasses and alpines, small bulbs.

Semi-extensive 10–20 cm Mixtures of low or medium perennials, grasses, bulbs and annuals from dry habitats. Wildflower meadows. Hardy sub-shrubs.

Before and after. A living roof can brighten up the dullest space.Georgina Cape

A living roof prior to planting and seeding. Dusty Gedge/Livingroofs.org

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structural strengthening. However, it is easy to encourage moss to grow on sheds.

• It is often reasonably easy to provide added structural support to a commercial shed, so allowinga heavier, wildflower-rich living roof to be installed.

Extensions, outhouses andbalconiesIt should be possible to install livingroofs on small extensions, outhousesand balconies. Again, whether asedum mat system or a heaviersubstrate-based system is used willdepend on the structure below.

Building a living roof – thebasics

While the exact choice of the type ofliving roof to be used will depend onthe strength of the individual buildingconcerned, it is always vital to ensurethat:

• The existing waterproofing is sound and does not leak. It may be advisable to renew the roofing layer before any installation takes place.

• The structure of the building to beconverted is sound and can take the load.

The need to take expert advice onthese two essential matters cannotbe over-emphasised.

How to do itIn some cases the cost of specialistliving roof products may exceed theoriginal cost of the building itself.However, it is possible to puttogether a small-scale living roofusing materials available in mostgarden centres and hardware shops.

It is possible to encourage mossesand lichens to grow on a lightweightbuilding without much work orexpense. However, if a roof is tosupport flowering plants, it requires aseries of layers.

The basic elements of any living roofsystem are these:

• Waterproof layer. The base layer. Added to the existing surface, this will give greater security and peace of mind even ifthe roof is already soundly waterproof.

• Root membrane. Waterproofing layers, such as asphalt and bitumen, are very susceptible to damage from plant roots and any root penetration may lead to leaks.A pond liner or butyl lining or 300micron damp-proof polythene should be laid over the waterprooflayer and, wherever possible, in one continuous sheet. Otherwise, the sheets should overlap by at

least 20 cm.

• Filter sheet. This sheet allows water to drain off the roof but stops the escape of fine materials in the substrate.

• Moisture blanket. For extensive living roofs, this blanket will

ensure that the growing medium (the soil or substrate) retains enough moisture to support life. Commercial ones can be bought which do not degrade but it is possible to use cardboard or old blankets to achieve the same effect.

• Drainage layer. Like the moistureblanket, this helps to retain moisture while allowing excess water to drain away. Commercial systems store water and are made of plastic or geotextile materials.Sedum mat on the roof of an extension.

Jeremy Linden

Filter sheet. Dusty Gedge/livingroofs.org

11Living roofs10

• Soils and substrates. The top layer. The growing medium should be lightweight and free-draining yet of a material that retains moisture. Many people use aggregates mixed with light sub-soils such as crushed porous brick and limestone chippings.

• Seeds and plants. Sow seeds on the substrate, or put in plug plants(small plants in individual cells) and watch them grow!

Plants and living roofs

Mosses and lichensThe lightest living roofs – and thesimplest to create – are thosesupporting mosses and lichens.

Mosses are a group of small greenplants that do not flower or fruit butproduce spores. They require suchsmall amounts of nutrients that manyspecies are able to live ininhospitable places, clinging to wallsand stone and tiles waiting for rain.

The ‘moss forest’ provides cover forthousands of microscopic animals,such as water bears (Tardigrades),and a habitat for other invertebrateswhich, in turn, are food for birds.Moss on buildings is often – andunfairly – associated with neglect,but it can bring many of the benefitsof a living roof, such as shielding theroof from ultra-violet light, absorbingwater and cooling.

Lichens are composite, symbioticorganisms made up of fungi (whichdominate) and algae orcyanobacteria. Food manufacturedby the vegetative element of theorganism through photosynthesis isenjoyed by the host fungus. As aresult, lichens are able to surviveextremes of temperature and droughtand can colonise surfaces too sterilefor most other organisms (includingmetal, glass and plastic).

Look closely and you will see thatthese anciently-evolved plants adorneven the most urban environment.Walls often support the greycushions of the moss Grimmiapulvinata or the conspicuous yellowseta (stalk-like structures) of wallscrew-moss Tortula muralis. Wherethere is enough moisture, carpet-forming mosses like rough-stalkedfeather-moss Brachytheciumrutabulum may be found. That

yellow crust you cansee on many tiledroofs is Xanthorialichen.

Although it ispossible to encourageor cultivate lichensand mosses, patienceis required becausethese are relativelyslow-growingorganisms. Somelichens, for example,may grow less than amillimetre a year!

There is a centuries-old tradition ofgrowing mossgardens in Japan.Self-established mosscarpets can beencouraged on a layerof sandy soil 20 mm

Drainage layer. Dusty Gedge/Livingroofs.org

Well-drained substrate. Dusty Gedge/Livingroofs.org

A mini living roof! Dusty Gedge/Livingroofs.org

Top: Wall screw-moss Tortulamuralis. Ron Porley/English NatureBottom: The moss Grimmiapulvinata forms attractive cushions.Ron Porley/English Nature

12 13Living roofs

deep or less and, if kept damp, mosscommunities will establishthemselves here through airbornespores. If you can find moss whichhas been stripped from a building (bythose who do not appreciate it!) youcan replant these sods on your ownroof. Even if planted sods fail, theywill encourage the colonisation ofother, better-suited mosses.

It’s worth noting that various speciesof moss will flourish on the sedum-type living roofs discussed below.

A number of companies specialise inproviding pre-grown moss mats andother means of speeding up mossgrowth.

Sedum roofsSedums are the most widely-usedplants for living roofs as they havemany advantages in terms of hardinessand drought tolerance. Beingsucculents, they actively store water intheir tissues and have a number ofways of reducing their need for waterin dry weather.

Under conditions of severe stressmany sedums change colour fromgreen through to red, purple andbrown. Although they are very tough,you must remember that sedumsgrowing on very thin substrates, or onsimple moisture mats, may die backand become patchy during periods ofextreme dryness.

Commonly-used species on livingroofs include white stonecrop Sedumalbum, S. hispanicum and S.reflexum. These species are notnative, however, so for preferenceuse biting stonecrop Sedum acre, arelatively common native of rockoutcrops and old walls. All sedumsare evergreen and most low-growingspecies flower for a relatively shortperiod in midsummer. Whitestonecrop and biting stonecrop havesome of the most spectacularflowering displays and are veryattractive to bees, butterflies andother insects.

There are three main ways toestablish a sedum roof.

• Seeding. Although this is the

cheapest option it will take time for the plants to fully cover the area.

• Cuttings or plugs. Place plants across the roof area.

• Commercial pre-grown sedum blankets. These can be rolled out on to the surface of the roof or the growing medium. A few companies now supply these mats ready-impregnated with wildflowerseeds to increase the diversity of plant species.

Wildflower roofsThe conditions on a living roof (free-draining substrates with low fertility)are ideal for the creation of highlydiverse and species-rich grasslandplant communities. More often thannot, these dry grassland ‘roof

Above: Biting stonecrop Sedum acre thrives on well-drainedground and has spectacular flowers. Roger Key/English NatureRight: Bumblebees enjoying sedum on a roof. Nigel Dunnet

Grasshopper on Sedum album. Native sedum species are preferred, however. Dusty Gedge/Livingroofs.org

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meadows’ are more successful thanthose that people try to grow in theirgardens.

Rooftop meadows have a number ofadvantages:

• A diversity of flowering plant species will result in a longer overall flowering season, thereby

extending the period during whichthe roof flora acts as a nectar source for insects. Late-floweringspecies are particularly useful in this respect.

• If the meadow is left uncut throughout autumn and winter, thestanding seed-heads will provide food sources for seed-eating birds,and the dried-out stems and stalks will provide over-wintering shelter for a range of invertebrates.

• Living roofs can support local or regional plant communities and vegetation types that might be endangered in the wild.

Calcareous grassland living roofsThe use of limestone chippings andmixtures of crushed brick andconcrete will allow a calcareousmeadow to develop. Such meadowsare very species-rich and can still be

found in the wild on steep slopes andthe remnants of unploughed pasture.The soils on these habitats are thin,typically between 50 mm and 100mm – the same sort of depth as thaton an extensive living roof. In thewild, these grasslands can support asmany as 30 to 40 species per squaremetre, so even a small living roofwill, potentially, be home to manydifferent plants.

Where living roof substrate depthsare relatively shallow (50–100 mm)low-growing and creeping speciessuch as the following may be planted.

At greater depths (100–150 mm) theseplants are suitable:

Field scabious Knautia arvensis

Greater knapweed Centaurea scabiosa

Wild marjoram Origanum vulgare

Viper’s bugloss Echium vulgare

It is better not to seed a living roofwith grasses as they may out-competewildflowers. Many wildflowers willcolonise your roof naturally but it isworth adding seeds of wildflowerannuals as they provide an early burstof colour and many are becoming veryscarce in the UK. Examples includescarlet pimpernel Anagallis arvensis,cornflower Centaurea cyanus, cornmarigold Chrysanthemum segetum,

Above: A living roof planted with wildflowers. DustyGedge/Livingroofs.org. Below: Many species appreciate drygrassland as a habitat. Mathew Frith

Common Lotus bird’s-foot-trefoil corniculatus

Cowslip Primula veris

Harebell Campanula rotundifolia

Hawkweeds Hieracium spp

Horseshoe vetch Hippocrepis comosa

Kidney vetch Anthyllis vulneraria

Lady’s bedstraw Galium verum

Common rock-rose Helianthemum nummularium

Salad burnet Sanguisorba minor

Small scabious Scabiosa columbaria

Thyme Thymus polytrichus

The distinctive yellow flowers of common bird’s-foot-trefoilLotus corniculatus. Roger Key/English Nature

17Living roofs16

corncockle Agrostemma githago,wild pansy Viola tricolor andscentless mayweedTripleurospermum inodorum.

Establishing rooftop wildflowermeadowsWildflower meadows can beestablished in a number of ways.

Seeding is the most cost-effectivemethod. Mixing the seed with aquantity of sand prior to sowingallows a more even spreading of seedacross the surface. If you are sowing

on to a sloping roof it can bebeneficial to tack an open hessian orjute mat over the sown mix to protectthe soil from heavy rain.

Wildflower plants can also beestablished using plugs or small pot-grown plants. This is more costly,but gives you greater control over thecomposition of the roof flora. Acombination of seeding and plantingcan also be effective. Both seedingand planting are best done in theautumn and spring. Dry summerweather should always be avoided.

Maintenance

Most people want a living roof that islow on maintenance. As with allother types of garden and landscape,the amount of work needed willdepend on the intended outcome! Ifa perfect, manicured green space iswhat’s required then the area willneed a lot of attention. However,extensive living roofs need relativelylittle maintenance. Semi-extensiveareas will need more attention tokeep them looking good and tomaintain their diversity of species.

Sedum roofsIf a pristine green carpet of sedums isthe goal, then this will mean a fairamount of weeding to controlinvading plants. This may have to bedone two or three times a year.However, a less intensive regime willresult in the development of a moremixed vegetation, as grasses and

other plants invade. If a sedumliving roof is left largely unmanagedit is likely to gradually develop into amore mixed community, with agreater proportion of grasses in thevegetation. However, somemaintenance – even if you onlyintervene once a year – should bedone to remove invading woodyplants (such as birch tree seedlings)that have the potential to disrupt, oreven puncture, the waterproof liningof the roof.

Wildflower roofsFor extensive living roof types itshould be possible to develop a

Top: Cornflower Centaurea cyanus. Peter Wakely/English NatureAbove: Scarlet pimpernel Anagallis arvensis. Paul Glendell/English Nature

This living roof has been designed to incorporate many different habitats. ZinCo GmbH

wildflower meadow with little or nointervention. Low fertility substrateswill give rise to short vegetation thatwill not need cutting back each year.Where growth is more productive ortall – as on a semi-extensive livingroof – it will be necessary to cut backand remove growth every year. Thiswill prevent the died-back remains ofthe previous season’s growth,accumulating on the surface of theroof. Unlike conventional meadows,which are normally cut in summer,it’s recommended that roof meadowsare cut back in late winter. Leavingthe dried and dead vegetation inplace not only provides over-winter

19Living roofs18

shelter for invertebrates and food forseed-eating birds, but also a degreeof protection to the plants beneath itduring severe weather. It can alsolook attractive.

Bugs and living roofs

Common, widespread and highlymobile invertebrates will easilycolonise living roofs. Examplesfound so far include many ladybirdspecies as well as various shieldbugs,

hoverflies, bees and grasshoppers.But since these species occur anywayin our well-tended and nutrient-richgardens, living roofs offer them littleextra. However, the owner of agood, dry grassland roof can hope toattract some of the more unusual andscarce insects that are linked withsimilar habitats in the wild.

A key feature of living roofs is thatthe growing medium is made up ofsubstrates such as crushed brick withonly a little soil mixed in. Thismeans that they are nutrient-poor,sparsely vegetated, well-drained andboth dry and warm, with areas ofbare ground. In turn, theinvertebrates they support are thosethat are warmth-loving (or heat-tolerating) species. These tend to bethose with a rather Mediterraneandistribution in Europe, and which inBritain are therefore right at the verynorthern and western edge of theirrange.

Such species are normally associatedwith habitats such as sandy heaths,chalk downs, coastal cliffs, dunes andbrownfield sites (land that waspreviously developed, then left to runwild). As a result of changing land-use, many of these formerly openhabitats are now in danger ofbecoming smothered by scrub and solosing their important floras andfaunas. Many nationally scarceinsect species occur on brownfieldsites and some of these are nowturning up on living roofs in England.

Field scabious Knautia arvensis, although in this case thefield is on the top of a building! Mathew Frith

Try to imagine a living roof as arockery, with boulders, gravel andother rough, dry substratesdecoratively arranged with only alittle soil. Instead of the traditionalalpine and succulent garden plants,populate it with native species.Plants like kidney vetch Anthyllis

The insects found in dry, warm habitats often include therare and the unusual, for example (from top) a squashbugSyromastus rhombeus, a weevil Ceutorhynchus geographicusand the leafhopper Aphrodes bifasciatus. Roger Key/EnglishNature

vulneraria, horseshoe vetchHippocrepis comosa, bird’s-foot-trefoils Lotus species, salad burnetSanguisorba minor, toadflax Linariavulgaris and native grasses are allassociated with unusual insects whichfeed on them. Clovers – Trifoliumspecies – are valuable forage plantsfor bumblebees, including thedeclining Bombus sylvarum and B.humilis. Wild mignonette Resedalutea and weld R. luteola are visitedby tiny white-faced bees (Hylaeusspecies), many of which are veryrare. Other important nectar andpollen sources for bees, wasps,hoverflies and butterflies are ox-eyedaisy Leucanthemum vulgare, varioushawkbits, Leontodon species andcommon cat’s-ear Hypochaerisradicata.

Wild mignonette Reseda lutea. Roger Key/English Nature

A mining bee Andrena clerkella laden with pollen. Roger Key/English Nature

21Living roofs20

A good living roof will also attractground-dwelling insects such aspredatory ground beetles and root- orseed-eating invertebrates. Theseparticularly favour loose, dry soilinto which they can burrow amongthe plant roots, or areas under largerrocks and stones. Such soil also suitsa wide range of soil-nesting solitarybees and wasps. Unusual visitorsyou might see include the bombadierbeetle Brachinus crepitans, theAdonis ladybird Hippodamiavariegata, mining bees and sandwasps, such as the sand-tailed digger

wasp Cerceris arenaria and theornate-tailed digger wasp C. rybyensis.

Small logs laid across the substratewill not only provide shelter forinsects but also make nesting sites forthe many small bees and wasps thatburrow into dead timber. Unlike logsresting in the moist humus of gardentopsoil – which rot down through theactions of beetle larvae and worms –these roof logs become sun-baked andhard, providing a different butnevertheless important habitat forinsects.

The sand-tailed digger wasp Cerceris arenaria. Roger Key/English Nature

Butterflies

A living roof is a great place toencourage those butterfly and mothspecies not normally found in rich,lush gardens. Being both low innutrients and well-drained, such roofsallow food plants for a number ofimportant butterfly and moth speciesto flourish. Horseshoe vetch, kidneyvetch and bird’s-foot-trefoil, forexample – all with beautiful yellowflowers – are important food plantsfor butterflies such as the dingyskipper and the common blue. Aswith other invertebrates, some of thespecies in the list below like bareareas of brick, shingle or gravel onwhich to sun themselves.

Sun-baked logs make a valuable habitat for many species.Dusty Gedge/Livingroofs.org

23Living roofs22

The grayling butterfly Hipparchia semele prefers grasses. Roger Key/English Nature

Species Substrates Foodplants

Brown argus Chalk to acid Rock-rose, dove’s-foot crane’s-bill, stork’s-bill species

Common blue Chalk to acid Mainly bird’s-foot-trefoil species and black medick

Dingy skipper Chalk, neutral Horseshoe vetch and bird’s-foot-trefoilspecies

Grayling Heath, sand, chalk Grasses

Small copper Chalk to acid Common and sheep’s sorrel

Small heath Chalk to acid Fine grasses

Wall Chalk to acid Grasses

Butterflies associated with dry habitats that may use living roofs

The common blue butterflyPolyommatus icarus will be

attracted to bird’s-foot-trefoils.Roger Key/English Nature

Birds

Even a small living roof can providea good feeding area for common birdspecies such as blackbird, song thrush,robin and wren. Dry grassland roofs,with plenty of good seed plants willattract seed-eating birds such asgoldfinch, linnet, greenfinch andchaffinch. If the roof is inBirmingham or London it may evenattract a black redstart, a bird rare inBritain but one well known for usingliving roofs on the Continent.

Centre: Robins will be attracted by theinvertebrate food to be found on living roofs.

Chris Gibson/English NatureRight: A Black redstart. Rare in Britain, thesebirds often use living roofs on the Continent.

B. Borrell Casals/ FLPA

25Living roofs24

Designing living roofs forwildlife

The best design is one that provides arange of microhabitats for wildlife.Even a small roof may provide anumber of miniature habitats, rangingfrom the bare and dry to the tall andverdant, benefiting many plants andbugs. Do, therefore, think about thefollowing, if the structure allows:

• Try to ensure that your roof has areas of shingle, gravel and stonesthat will remain relatively bare. Such areas will provide a sanctuary for species that like bare, dry ground. Small geometric areas covered in gravel,or the addition of rock cairns, can also give a ‘landscape’ feel to a living roof. Even on a deeper semi-extensive roof, consider

having some shallow, bare areas to increase the range of habitats.

• Even on shallow extensive living roofs there may be areas that can hold deeper substrates. If there is a supporting structure such as a wall or a pillar below, a mound or a ridge of deeper substrate could be applied above. This will allow taller vegetation to grow.

• Placing small boulders and dry rotting logs on the roof can provide important microhabitats for bugs, fungi and other species.

• Use a native seed mix or plug plants, preferably from a recognised supplier. A cheaper alternative is to collect your own seeds from a local meadow, wasteland or dry grassland site (assuming you have permission from the owner!)

Enjoy it

Designing and tending a living roofin the garden should be fun. If, overtime, things do not develop quite asexpected then add a little moresubstrate where possible or sow afew more seeds, or both. Get up onto the roof and have a look at thebugs and beasts that you haveattracted. Above all, let other peopleknow and help spread the word!

Please remember to seek out andfollow all relevant safety advicewhen accessing roofs and highplaces.

A green oasis. Dusty Gedge/Livingroofs.org

In the construction industry aroundone-quarter of all deaths and seriousinjuries are due to falls from ladders.

If using a ladder or other equipment,please refer to and follow themanufacturer’s safety instructions.

Both English Nature andLivingroofs.org are keen to hear frompeople who have made a living roofin or around their garden.

Please contact:gardenroofs@livingroofs.org.uk orsteve.berry@english-nature.org.uk

Pictures courtesy of Zinco GmbH,Livingroofs.org, Nigel Dunnet,Mathew Frith, Georgina Cape,Jeremy Linden

27Living roofs26

Finding out more

For further information on livingroofs and biodiversity go towww.livingroofs.org orwww.greenroofs.com

Nigel Dunnet and Noel KingsburyPlanting Green roofs and livingwalls. Timber Press 2004

Green roofs: their existing status andpotential for conserving biodiversityin urban areas. English Nature Research Report No498. 2003

Jacklyn Johnson and John Newton. Building green: a guide to usingplants on roofs, walls and pavements.2004Available from www.london.gov.uk

Useful organisations

Buglife170A Park RoadPeterborough, PE1 2UFTel: 01733 201 210www.buglife.org.uk

Royal Horticultural Society80 Vincent SquareLondon, SW1 P 2PETel: 020 7834 4333 info@rhs.org.uk

The Wildlife TrustsThe KilnWatersideMather RoadNewark, NG24 1WTTel: 01636 677711www.wildlifetrusts.org

Plantlife14 Rollestone StreetSalisburyWiltshire, SP1 1DXTel: 01722 342 730enquiries@plantlife.org.uk

This English Nature leaflet is one ofa series about gardening with wildlifein mind. The others are: Wildlife-friendly gardening: ageneral guide Plants for wildlife-friendly gardensAmphibians in your garden Reptiles in your garden Minibeasts in your garden Focus on bats Composting and peat-free gardeningMeadows – how to create one in yourgarden Garden ponds and boggy areas:havens for wildlife Dragonflies and damselflies in yourgarden Enjoying moths and butterflies inyour garden Mammals in your garden Wildlife on allotments Birds and your garden.

In preparation:Another kingdom: fungi in yourgarden Green gems: mosses and liverwortsin your garden Not all bad: slugs and snails in thegarden How does your garden grow?Children and wildlife.

All leaflets are freely available fromthe English Nature Enquiry Serviceon 01733 455100/101/102 or e-mailenquiries@english-nature.org.uk

English Nature also produces aninteractive CD: Gardening withwildlife in mind. This has detailedtexts and photos of 500 plants and300 of the more common garden‘creatures’, and shows how they areecologically linked.

Details from The Plant Press, Freepost, Lewes, BN7 2ZZ.Alternatively, call John Stockdale on01273 476151 or e-mail john@plantpress.com