Native to limestone bluffs, cliffs, and wooded slopes of the central Appalachians, cliff green is a dense, dwarf evergreen shrub with fine, boxwood-like foliage that stays under a foot tall but spreads outward by branches that root where they touch the ground, eventually forming sizeable colonies. Flowers are tiny and inconspicuous; the plant earns its keep as year-round low structure and groundcover in the shade.
It's a genuinely finicky plant to establish, wanting acidic, moist-but-well-drained soil in a sheltered, shaded site — it can decline or die out even under seemingly good conditions, so give it the coolest, most protected spot available rather than treating it as a tough, plant-and-forget groundcover.
Root rot
Plants wilt, yellow, and stunt even in moist soil; lower stems and roots turn brown, soft, and mushy and the plant may collapse. Most common in heavy, wet, or poorly drained ground.
Improve drainage and stop overwatering, and never plant too deep. Lift and destroy badly affected plants along with the soil around the roots. Grow in raised or free-draining beds to prevent it returning.