One of your jobs Joe? You hafta incorporate a planter into the wall? I did a roof years back that had a small tree growing out of a mortar joint in the chimney. Ive seen them growing out of dummy flues too.
always amazes me how determined mother nature is that trees can grow out of cracks in rocks and eventually split them .
Reminds me of that "day after" show that was on History channel...all the plants and trees just take back over...