Green Roof Mulch

The Berry Prairie has a tannish-tone to it these days.  One of the big issues in the original roof was that the black growing medium (the fake dirt) absorbed so much of the intensive, high-elevation sun that it was very, very hot on a regular basis.  The plants did not seem to care for this much, so we've tried to tackle this problem through two different solutions:

1. Pop-up irrigation.  The cool water coming from above (rather than below as with the drip in the previous edition) will help cool all layers of the growing medium.

Photo from Sept. 19

2.  Light-colored mulch.  We used a "rose" colored, 3/8" pea gravel spread 1" deep all over the roof.  This lighter color will help prevent so much absorption and look/act more like a native prairie with their light-colored soils.

You can see the difference in color between the tan pea gravel (right and top of image) and the darker growing medium (left of image)

Written by Brenna Marsicek, UW Biodiversity Institute