Sunday, 20 December 2009

A Succulent Roof


Instead of digging grass and eucalypt seedlings out of your gutter, you could create a proper lawn on your roof (without trees I’d suggest…). Of course a little infrastructure is needed but there are some pay offs.

An article and media release from a recent issue of ASBS Hortscience, the scientific journal of the American Society for Horticultural Science, lists the gains as “improved storm water management, energy conservation, reduced noise and air pollution, improved biodiversity, and even a better return on investment than traditional roofing”.

I’m not sure what ‘improved biodiversity’ means but I assume more bugs and animals enjoying your roof, as well as the few extra plant species you’ve added.

You do need to select your plants wisely and a common (and tough) succulent called Sedum is coming up well in trials. In fact I saw the sedum roof (pictured above) being trialled at the South China Botanical Garden when I visited there a few weeks ago.

As you would imagine, the depth of soil or rooting material also determines how well the plants survive in this tough, dry habitat.

In a four-year study by Kristin Getter of Michigan State University, the minimum depth of growing material was 7 cm. Any shallower and growth was too slow, while adding more material didn’t improve the results significantly. That said, they do suggest that the deeper the growing material the healthier the plants are likely to be.

Twelve species of sedum were trialled with the toughest being Sedum floriferum, Sedum sexangulare, Sedum spurium ‘John Creech’ and Sedum stefco.

We can all look forward to a green and succulent roof above our heads.

Images: Trialling sedum on the roof of a research building at the South China Botanical Garden in Guangzhou, China.

1 comment:

Rolf Matchen said...

Wow, I've never seen anything like that! A pasture on top of the roof? That's very innovative and refreshing!