The grass roof at Hilldrop is how it all began for John Little. All the techniques and methods in the online guide were used to construct the roof on his house. Furthermore, all of the other green roofs in his garden use the same or similar methods.
Using site spoil to make a grass roof
Whilst we would now recommend using a good green roof substrate, these were not available back in the later 1990s. More to the point John wanted his house to as little impact as possible. The building was designed by Jon Broome and was as sustainable as it could be at the time. Therefore the use of the soil excavated for his footing seemed to be best idea. Now John’s house is on clay. So the soil and sub soil is not necessarily best suited for a wildflower rich green roof.
Yet it continues to surprise.
From brown grass to ox-eye daisies
The roof changes depending on the weather in any given year. A dry summer will see the grass brown off quickly. As John says, ‘There’s nothing wrong with brown grass on a roof, I like it’. Though in wetter years the roof can be a sea of Ox-eye daisies. Even in the spring the roof is alive with colour. Muscari bulbs bloom. their small blue flowers attracting early solitary bees. And although the roof is a grass roof, sedums hung the edges of the roof in the drier areas.
The year of the orchids
The biggest surprise bloomed on the roof after almost 15 years. In 2012 bee orchids appeared. Within the soil, perhaps the seeds had lain dormant awaiting the perfect conditions. The year before was the year of the exceptional dry spring. Perhaps this spell had opened the clay soil up and triggered their germination. In fact they bloomed for a few years and were then gone. That is the way with bee orchids.
The rest of the green roofs at Hilldrop
The grass roof is only one of the many at Hilldrop. The summer house is bedecked with a wildflower green roof, whilst opposite is the ‘twitch grass’ roof. This is home to mice! Of course there are a few bike sheds and a few containers with green roofs as well.
We will be running a workshop on 21st July this year on Designing for Urban Nature. We will have the event details here soon But in the meantime why not join the celebration and build yourself a green roof using our guide.