Cob: House plans/living roof

[Waiting4 TheDay]

Amanda,

Your gabions got me thinking....as far as a retaining "wall" for a living 
roof, I wonder if a thin, flexible wire (chicken wire?) could be laid on the 
roof around the edge, say two feet in from the edge with the rest hanging 
off, then large gravel piled on top of it, then have the wire wrap over the 
top of the gravel to be held behind that ring of gravel by more gravel.  
Kind of like a gravel sausage.  Just thinking out loud.

My criteria for a roof plant would be drought-tolerant, aggressive 
spreading/rooting, and something special about it.  Grass just wouldn't do 
it for me, not unless I wanted to raise rabbits on my roof (and then the 
hawks and owls would think I'd opened a buffet).  And while I might allocate 
an area for lavender, rosemary, etc., these are more shrub-like and won't 
provide good coverage.

As far as mint, they shouldn't have any problem.  They are incredibly 
aggressive spreaders, so much so that I don't recommend my customers even 
put them in the ground unless they fully understand the consequences.  And 
as far as tough, after a Saturday at the farmer's market, an apple mint in a 
six inch pot got stuck in the corner of the van and left for a full week 
during the middle of summer.  It looked dead and the soil weighed about as 
much as styrofoam.  I put it in a pan of water and let it soak for three 
days.  Within a week there was new growth coming out.

I'd also considered, on a porch roof, putting out desert plants.  Not only 
do we have a couple of very hardy Bunny-ear/prickly pear (Opuntia) cactus 
native to the U.S., but also a lot of the southwest flora is hardy in the 
middle midwest (I'm in southern IL) if given very good drainage during the 
winter.  Ocotillo, creosote bush, and some agave and cholla will all do fine 
from zone 6 or 7 south so long as their soil doesn't hold water during the 
winter.


Chuck


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