The Magic of Green Roofs

It has been three years since we planted the green roof for our new house with wildflower plug plants, which has turned out to be a fabulous success. For many, “green roof” is synonymous with “sedum roof”, p1080079we started off by colour bombing it with annuals while the slower growing perennials developed.
This sense of progression and change – like a wildflower meadow – is part of its fascination. Fortunately I can see it from my office window on the first floor! Its colours change through the season and species come and go depending on the weather. It’s much past its best now, but still lovely.

Green Roof in 2014
Green Roof in 2014
Also like a wildflower meadow, the roof serves as a wonderful habitat for all sorts of invertebrates and birds as well. Our wagtails love it, and we see different finches on it regularly too. Fingers crossed we might even have something nest on it next year!
p1080073Conditions on the roof are almost opposite to the wet clay hereabouts, so we can create diversity as well as a very different look with it. Wild Thyme and Scabious (pictured) do very well on it, for example, which we would never see normally here. There are some areas where the growing substrate is evidently more fertile than in others and the moisture retention in the substrate also varies, which gives diversity to the flora and flora within the roof too. Some areas still have a lot of bare earth, whereas others have almost tussocky grass.
p1080085It can be pretty hostile for the plants on the roof, which means I don’t need to do much more than weed it a couple of times a year. Things don’t grow to great size, and annual weeds generally don’t survive at all. In the first year I watered it a couple of times but now I don’t bother. I’ve just sown some Yellow Rattle this year to keep the grasses down a bit in some sections, too. What’s not to like?

Biosolar Roofs

What is a biosolar roof? Simple – it’s a green roof with solar panels.

I wish I’d known about biosolar roofs when we built our house; instead, we have a really nice green roof area and a smaller flat roof with solar panels on. We should have combined the two.

Solar panels and green roofThere are many benefits to green roofs, which I’ve written about before. They range from the obvious – their aesthetic appeal and the biodiversity they bring – to the more obscure. Their insulating properties are excellent and they protect the roofing membrane from getting photo degraded, extending its life. Urban planners are particularly excited about them as a way of controlling water run off and lowering temperatures in city centres.

Combining green roofs with solar panels gives you further benefits. Most obviously, solar is the coming renewable technology and will soon become an efficient way of generating electricity without subsidy, even this far north.* Our panels here worry me because they’re pretty exposed, and would be much better anchored by several tonnes of green roof substrate. It also turns out that mounting them on green roofs reduces their operating temperature and increases efficency. Like ground mounted panels, solar panels on flat roofs offer the potential for a tremendous variety of micro-habitats. Rainfall and light varies according to the position of the panel. At its leading edge there is water running off its face and sun. Underneath the panel it’s relatively dark and dry. It’s almost like a synthetic woodland, which lends itself to establishing a tremendous variety of plants. If these plants are native that will mean a tremendous variety of invertebrates.

My interest in biosolar roofs was piqued at a conference in London hosted by the indefatigable Dusty Gedge, doyen of green roofs, to whom my thanks for the use of this photo. His partner Gary Grant has suggested a species list for biosolar roof plants, which we’ve used as the basis for the plug plants for biosolar roofs selection on our website.

*Given the current regulatory environment, the only biosolar roofs being installed at the moment in the UK are sadly by those folk who already have solar, or by companies looking to brush up their CSR (Corporate Social Responsibility) credentials.

Habitat Aid Newsletter No.5: 13th May 2010

This cold dry weather is a nightmare, but I suppose at least it’s given me time to sit down and write a newsletter. I’ve been a very busy boy over the last month, so much to catch up on.

We ran our first course in April, which seems to have been a great success. Tutored by Hugh Roberts of Environments for People we all learnt how to build a wildlife pond, now sitting in front of me. Thanks to Hugh and to our wetland plant supplier Gower Wildflowers. The pond’s already populated by a selection of interesting looking invertebrae, and the swallows are collecting mud from it as I write. All very rewarding. Next off are our meadow days, run by Sue Everett, on the 11th and 12th June.

I flogged up to Sheffield last week to go to an intriguing workshop on Green Roofs and Living Walls, which is an area we’re keen to get more involved with. We already have a relationship with a consultant, and supply generic native seed and plug mixes for green roofs, but hope to do a lot more in future to encourage folk to plant native plants rather than just use the sedum mats they have done in the past. Green Roofs in particular seem to me to be a fantastic and practical way to encourage biodiversity in urban areas – among other advantages!Green roof in Sheffield

I also hope we can do more work with seeds, where we are starting to supply end business customers directly. After a successful trial we are supplying the British Beekeepers’ Association (BBKA Enterprises Ltd.) with two native seed mixes particularly helpful for bees, which I have high hopes for. We’re also supplying Flowerworld with the seed for a 50,000 sachet promotion at Morrisons to promote the Bumblebee Conservation Trust.

Our other bee related news is that we’re expanding our range of plants and exotic trees for bees as a result of some suggestions from Andy Willis at the BBKA Spring Convention and Norman Carreck at the Laboratory for Apiculture and Social Insects at the University of Sussex. They’ll be supplied by R.V.Roger and available from this autumn.

We are seeing the first fruits of our work with designers, sourcing native plants for some very exciting schemes. We’re both promoting those currently working with habitat creation in mind, and encouraging others to think about it more.

As to life here, Kingsley the new ram has been a success and the mad Runner Ducks are laying again, albeit mostly not in their Duck house. My bees are happy too, and I’ve set up a couple of bait hives for them. Mike the gardener’s grand veg plot looks great and our various mini-meadows look promising too – if only it would rain!

Poll Dorset in the orchard
Post Kingsley moment in the orchard

Points North

R.V.Roger, Pickering
A Proper Nursery
I had a good time on my trip last week. First stop on Wednesday was Pickering on the Yorkshire Moors and the obliging Ian Roger, who runs R.V.Roger – a proper plantsman running a proper nursery, a thriving family business founded in 1913. Although we use Ian for fruit trees and bulbs he has a fantastic collection of seeds, roses and herbaceous too. Then off to Crayke and to the lovely Dutch House, where you can find an arts centre with a cafe, and an eco garden with wildflower meadows (from Habitat Aid seed!).
Art Courses in Crayke
Dutch Art Pig
It’s the brainchild of Cecile, a graphic designer, and Sjaak, the manager of the museum gardens at York. The site is lovely, with a stream running through it to boot, and on a circular tour around the village which takes walkers right through the meadow area. Good luck to you – it’s a venture that deserves to succeed. Wednesday night spent as the only guest at the Strines Inn just outside Sheffield – another proper job – the Good Pub Guide triumphs again. Sheffield on Election Day at a pretty thought provoking Green Roof workshop, then a drive to Louth past endless oilseed rape fields (no bees) and Hawthorn hedges (no Blackthorn).
Louth, Lincolnshire
Exquisite Copper Beech, Louth
Stayed up much too late on Election night and somewhat hung over for my meeting with Steve the seed man, but stayed awake enough to flog over to the Malvern Show that morning. Malvern was slightly anticlimactic to be honest, but met some good folk including Gilly from the British Plant Nursery Guide and Brigit from the Big Green Bus. I bought my annual Pitcher Plant from the ravishing Hampshire Carnivorous Plants stand, promising to look after this one better. Slept well on Friday.
North of Louth
A Long Way From Somerset

Green Roofs

Sheffield RoofJust back from a very jolly road trip to points north and east – Pickering, Sheffield, Louth, and Malvern. I’ll post a blog on the rest of the trip in a few days. I was at Sheffield University on election day for a BALI workshop on green roofs and living walls, which is an area I’m interested in getting more involved in and promoting actively. With increasing urbanization and improving technology it seems a no brainer. Fascinating stuff it was; we had three expert speakers and a tour of some roofs afterwards. I came away enthused, with a lot of detail and some key impressions…

Green roofs can/will bring fantastic benefits to urban environments. I hadn’t thought much beyond the creation of visually attractive amenity spaces and habitats, but they have other advantages too. They improve thermal and acoustic performance and extend the waterproofing life of a roof, as well as benefitting atmospheric conditions. Interestingly, they also not only reduce the quantity of rainwater run off but also help regulate it, which is apparently becoming an increasingly problemmatic area.

The technology behind living walls is still quite new and on a large scale seems tricky and expensive, but in the long term they could be an integral part of urban architecture in a world suffering from climate change and diminishing natural resources. Right now small units, enabling people can grow their own salad on a balcony, for example, seem a great idea.

Green roofs are more straightforward, but not simple. Although construction methods are tried and tested, a one size fits all approach to design and planting absolutely won’t work and they need to be planned and installed with a great deal of care and attention to detail. There are, however, some really good quality specialists about who can help, and it’s worth spending the money on them to avoid expensive mistakes. I can point you in the right direction if you’re interested.

On the other hand, maintenance of an extensive green roof (as opposed to an “intensive” roof) is surprisingly simple and low key, unless you start with just sedum and want to keep it that way – so have to weed regularly to prevent it being overwhelmed over time by native species.

Extensive green roofs aren’t just about sedum mats (below left), which look good all year round and provide instant effect – but which will be less helpful in terms of biodiversity. You can do much more with the planting to include all sort of species, according to situation and design. The demo section of roof below right started off as a sedum mat with other seeds impregnated in it, and although it wasn’t the best time of year to see it looks a treat, with Sea Thrift, Yarrow, Chives and all sorts. Nice habitat!
Sedum matNatural green roof Around the corner from this area was a raised section with a deeper layer of substrate planted like a traditional herbaceous border for dry conditions – ornamental salvias, Rosemary, that sort of thing…

Formal green roofThe intensive amenity roofs we saw struck me as being rather less exciting and, of course, they require a lot more maintenance. Amazing what can be done though, even 20 floors up, and much better than just looking out at a roof with air conditioning units on!