That Coveted Mossy Look

Mossy patina on a planter in part shade
Arabis sturii, armeria maritima (white) and chamaecyparis obtusa 'Nana'

One of the things that everyone loves about hypertufa, including me, is the "instant aged" look of worn edges and bits of moss in the crevices.  The worn edges can be accomplished rather quickly by working a rough stone (or chipping hammer) over the square edges of a new container, but the moss is harder to come by.  The first hypertufa containers that I made for my current garden are 4 years old and sit in full sun.  They aren't mossy at all on the parts that face the hot summer sun, but show some interesting green on their shady sides.  The container pictured above sits on my deck and gets only morning sun.  It's a few years old, but the moss grew effortlessly in the small holes left behind after the exposed peat moss in the original mix gradually rotted away.  Same goes for the round shrub container below, which is in shade for most of the hot sun of the summer afternoons.

Kolkwitzia amabilis 'Maradco'

I've tried mixing moss with buttermilk and painting the slurry onto fully cured containers but the results were pretty poor.  In the sunny spots where the moss got started, it held on only until the next bout of sun and heat killed it for good.  In the shady areas moss grew whether I introduced it or not.  I've given up trying to control the patination of my planters and left nature to take care of it.