Reach for the (Green) Stars!

Why not have a smart new resolution resolution this year... or revolution, depending on how you look at it? If you’re living in something other than a bungalow, take a look out of your bedroom window and take in all the roof spaces you can see – and now imagine them covered in a stunning little landscape of flowers and plants. These “green roofs” could be magnets for wildlife, with birds feeding on all the insects and seedheads, as well as soaking up all the excess rainfall and airborne pollutants. 

So, as well as maximising all your garden spaces, a new aerial layer would also tick all the right boxes for saving the planet, at the same time as transforming spectacularly dull structures into really special garden features.

The original concept of adding a layer of vegetation to a roof can still be seen in many Scandinavian and Hebridean communities. Even pitched roofs are often completely covered in the sods of grass and other vegetation that were dug out of the ground when the buildings were first built. This is obviously a very sustainable and cost- effective idea, but it is not done for decorative or wildlife benefits; it’s purely for keeping out the worst of the weather and creating a cosy home.

Modern green roofs are more likely to be seen on large commercial buildings and they are now highly complex systems. They incorporate the latest waterproofing and protection methods for the roof itself, combined with lightweight substrates and effective water removal and irrigation processes. The planted surface is invariably a mixture of sedum succulent species as they are relatively cheap to produce, but they aren’t particularly exciting. This refined technology and the requirement for all new developments to meet biodiversity targets means that green roofs are now an essential element in the construction process. 

It also means that for us gardeners the same principles can be applied to create simpler solutions on a much smaller scale, which can elevate a garden from a one-dimensional plot to a multi-layered landscape. So, how do you start and how difficult is it? We’ve all got sheds, garages or porches and virtually any of these can be fitted with a green roof, provided you follow some very simple common- sense considerations regarding their load bearing capacity. 

Any wooden framed building would need the addition of bracing bars and strengthened uprights – but don’t let that put you off as it’s a relatively simple job for anyone with some basic joinery skills. Next you need to ensure that the roof itself is waterproof and has a seamless covering; again, not impossible for the likes of you and me. There is no definitive right way to build a small green roof and most successful ones have come about through experimentation and creativity. Rest assured that with a little research and some sage advice you can easily convert an existing building into one suitable for a green roof.

Once you’ve got your waterproof and stable building, you can then get on with the interesting bit – the planting! This is where you can really let your imagination run wild, as long as you remember that for most plants it represents a pretty hostile environment, fully exposed to sun, wind, rain and whatever else the weather has to throw at it, plus there is only a shallow depth of substrate to root into. However, despite these spartan conditions, there is a vast palette of plants to choose from, in particular Mediterranean herbs such as Rosemary and Origanum together with small bulbs such as crocus and dwarf tulips. 

The image shows a shed with a green roof which we sowed with a mix of herbs, sedums and other dwarf plants over seven years ago. It doesn’t have any form of irrigation and, with a bit of judicial weeding, keeps looking great. Why not give it a go – trust me green roofs can be addictive!