Green roofs are slowly but surely appearing in Britain.
It’s not that they are new it’s just that they we Brits seem to intrinsically mistrust them.
Or is the cost that makes us hold back?
A lovely boat house
This lovely roof [see main pic] was in an especially nice location. I spotted it up near the top of Scotland. It was a photo that I couldn’t resist taking a few years ago when touring that beautiful part of the world.
Here I suspect turf was dug from nearby and established on this lovely old boathouse roof. No doubt the high rainfall helped this. Native grasses and ling [Calluna vulgaris] dominate this green covering.
Elsewhere green roofs are popping up on all types of buildings. Although still novel, one is just as likely to see a roof covered with plants in a domestic garden, on top of an inner city high rise or covering the entrance building to some great garden.
Benefits of a green roof
These are largely environmental with rainwater absorption and heat moderation being the key factors.
However gardeners are most likely to have a green roof for the ornamental effect. The unquestionable benefits offered to wildlife runs a close second.
Flowering roofs look beautiful in summer. They require only the minimum of maintenance.
Bees and other beleaguered insect life will be the greatest benefactors of green roofs but all wildlife will derive some benefit.
These flowering roofs are usually covered either with a carpet of Sedum or wildflowers.
Not any roof is suitable to be a green roof
Before you race out and cover your garage roof with a mat of Sedum or sow a mixture of wildflowers up there, it is vital that the roof is assessed. It needs to be assessed to see if it can carry the extra load.
Some internal strengthening may be necessary. And it may be better to build this into a new building rather than retrofit.
Either way, it is certainly necessary to plant over a waterproof membrane. You’ll also need a specialist growing medium to keep your plants happy.
In many areas the installation of an irrigation system to keep the roof alive during prolonged drought is a must!
Is there a green roof near you or do you have one yourself? If so I would be interested to hear what you think of them.
I considered covering our garden studio roof with plants but rejected the idea on the grounds of significant extra cost. Instead I have used the money to provide insect friendly plants elsewhere in the garden.