It's hard to imagine more serviceable ground covers for shade than these Asian natives. Though slightly less cold hardy than their Liriope cousins (see page 416), they're just as care- free, needing little more than well-drained soil and shelter from hot sun. Deer don't generally bother them. Plant them in large sweeps in areas where you don't want to mow or under large trees where grass won't grow. They also do well in containers. Use them for their lush evergreen foliage; the summer flowers, borne on short spikes, are largely hidden by the leaves.
It's easy to obtain more plants by division. Use a sharp spade to divide clumps in early spring; or use a knife to divide clumps sold in flats or cell-packs at garden centers. To get divisions of mondo grass (O. japonicus, O. planiscapus 'Nigrescens') off to a fast start, trim the roots back by half before replanting. This encourages rapid root growth.
O. intermedius 'Argenteomarginatus'. AZTEC GRASS. Forms foot-tall clumps with a cascading look and spreads widely and aggressively. Thin, dark green leaves with yellowish white margins grow 112 ft. long, 12 in. wide; white flowers are followed by bright blue fruit. Sometimes sold as Liriope muscari 'Variegata', but that plant has violet blooms.
O. jaburan. GIANT LILY TURF. Sometimes sold as Liriope gigantea. Grows 23 ft. tall, 112 ft. wide, with dark green leaves to 1123 ft. long, 12 in. wide. Clump forming; does not spread. Nodding clusters of small white flowers are followed by showy fruit in metallic violet blue (attractive in arrangements). 'Vittatus' (sometimes sold as Liriope muscari 'Variegata') has leaves edged in creamy white.
O. japonicus. MONDO GRASS, MONKEY GRASS. Dark green, grasslike leaves grow 812 in. long, 18 in. wide. Forms dense, 6- to 8-in.-tall clumps that steadily spread by under- ground stems to form an evergreen mat at least 1 ft. across. Short spikes of lilac flowers are followed by metallic blue fruit. Makes an excellent shade-tolerant lawn that never needs mowing, though it takes several years to fill in. Great for filling cracks between pavers and stepping stones. A number of dwarf selections spread much more slowly than the species; these include 'Gyoku Ryu' (12 in. tall), 'Kyoto Dwarf' (24 in.), and 'Nana' (3 in.). 'Little Tabby' (also sold as O. planiscapus 'Little Tabby') and 'Shiroshima Ryu' (also sold as O. japonicus 'Variegatus') have green-and-white striped leaves and grow 46 in. tall.
O. planiscapus 'Nigrescens' ('Arabicus'). BLACK MONDO GRASS. Nearly black, grasslike leaves grow to 14 in. long, 1814 in. wide. New leaves are green, but they soon darken. Spreads slowly, forming tufts to 8 in. high; clumps can reach 1 ft. across, but they don't form a thick carpet. Flowers are white or (sometimes) light pink. Looks great in mixed containers; striking when combined with yellow or chartreuse foliage, such as yellow creeping Jenny (Lysimachia nummularia 'Aurea').