I have an earth bank in my garden, created a few years ago when I dug into the
hillside to make a flat area. The bank is mostly at 45 degrees, and for the
time being I have grassed it. It has stabilised and all is well, so soon I will
plant it with ground cover. The problem is the part of the bank that is
steeper. It is 70 deg at its steepest, and every year a bit more shale falls
down due to frost. With more enthusiasm than sense I ordered 20 tons of hard
white limestone, and I have built a retaining wall 10ft high and 20ft long. I
have left little niches in it for planting, but the immediate problem is that I
now have a huge expanse of bright white rock to look at. Honestly it really
hits you in the eye. I bet they can see it from space! Anyway, I'm looking for
ways to tone it down, and I thought about the moss and other green gungy stuff
that is growing quite happily on ancient walls nearby. Does anyone know how I
can speed nature up a bit, and get a 50 year old covering of mossy stuff in a
much shorter period of time?
I should add that what I know about gardening and related topics could be
written on the side of a bilberry.
Thanks in advance to anyone who can help out.

Bill