In the past twenty years architects and town-planners have attempted to make use of the ‘lost’ space of roofs to extend the amount of green space in towns and cities.  Green roofs tend to be mass plantings of sedums and sempervivums.  As well as attracting small insects and animals the system insulates the building, acts as a water reservoir and is reputed to filter pollutants from the air.

Green roofs may benefit the urban environment in practical ways but, most of all they are very attractive. They provide a voluptuous connection between buildings and their organic surroundings.  The foliage colour changes with the seasons and the flowers make an attractive patchwork of yellow, white and pink.   Given their beauty, it is no surprise that they have been taken up by garden designers. (So much so that at a recent Chelsea Flower Show every flat plane – roof, compost bin and beehive  – seemed to be covered with a sedum carpet).

Green carpets can be bought ready-planted in rolls to transform the roofs of sheds and garages.  Grown on a plastic webbing that holds the growing medium together and sold by the square metre, the sedums used are the low, creeping species: S. acre, S. hybridum, S spurium, S lidium S rupestre and S. album.  Before attempting a makeover on your own shed, though, ensure that the structure is strong enough to take the weight.