Tuesday, August 05, 2008
Garden Reading: Planting Green Roofs and Living Walls
(Can you tell I've been studying this book?? Hehe. It came to me in pristine condition...)
Nigel Dunnett and Noel Kingsbury have brought an impressive amount of information together on this topic. For those of us with a cursory knowledge of roof gardens (at best), this book expands our knowledge exponentially. For starters, green roofs can be intensive (those that are cared for similarly to a regular garden) and extensive (those not intended to be used by people, per se)...or, a combination of the two. The term ecoroof is synonymous for green roof and is preferred by some, especially in areas where the roofs may not be green all year.
Probably most of us have seen a roof garden, especially if you live or visit an urban area where ground space is at a premium. I glimpsed one out my hotel window in Richmond, VA, recently, but didn't get a further look as left we exceptionally early the next morning. I've also seen one (from a distance) while visiting in Seattle, WA. However, they're not particularly common out here in the suburbs.
This book explores options way beyond our simple idea of roof gardens. The authors are interested in green roofing worldwide and examples are given from many countries. They point out that Germany has been a leader in this field. While it is somewhat easier to conceive of some of these innovative gardens on a flat surface, it appears that sloped roofs can also support various types of ecoroofs (although they are more problematic).
The estimated costs were rather startling but not surprising. It was suggested that incentives could be offered to encourage this type of roofing. The benefits were numerous such as reduced flooding, temperature reduction and wildlife habitat.
This is a serious book about a serious topic. It's well researched and referenced. It's clearly a book intended to impart information to a wider audience. I could easily see it as a text for a class.
I'm uncertain about the more utilitarian ecoroofs. It's suggested in the book that native plants can be used so that the roofs blend in. There were pictures of some natural roof gardens that were quite impressive. However, on a small scale, or on a personal level, it's a bit hard for me to get past that some of them look...well, untended. The suggestions that some roofs could be maintained with naturally occurring plants or windblown seeds was also a bit harder for me to appreciate. Those sound like weeds to me and I don't know that I'm at a place where I can appreciate them on my roof (and from there...in a carefully tended garden below?) ,
I remember living in the Seattle area and uncared for roofs would often sprout moss and sometimes trees. This was not considered desirable. It's going to take some time to change attitudes and develop appreciation for some of these new roofs, I think.
In addition, the wildlife habitat was a bit disturbing, too. It's suggested in the book that insects and some species of birds might find them hospitable and that this would replace their displacement during construction. I remember living overseas and seeing rats on roofs, not a habitat I would encourage (nor, I expect, would the authors). I also remember pigeons being particularly messy in decorative tiles that were outside our dorm room windows when I was in college.
On the other hand, I grow iris tectorum, Japanese Roof Iris, and it's not at all hard to imagine how lovely it would be on a green roof. I suppose I'm more supportive of the garden type roofs...maybe simply because that's all I've really been exposed to. I also loved the idea of, for instance, the mall in Germany that has made an incredible green area out of its roof....with many uses and purposes. How could anyone not like the idea of bringing green, from lush grassy park like settings to out-and-out vegetable gardening, to areas where there isn't any?
Thanks to the authors, Nigel Dunnett and Noel Kingsbury, for compiling so much information into a usable format. I'm sure their work will be studied and used by many who will be bringing us exciting advances in the world of horticulture. I'm on the lookout, now, for green roofs and will bring an appreciation to (for) them that I didn't have before.