Ornamental · Asparagaceae
Mondo Grass
Ophiopogon japonicus
Given shade and steady moisture, mondo grass lays down a soft mat of dark green blades that asks for almost nothing.
Partial shade
Every 5–10 days
USDA 7–10
6–12 in · 15–30 cm
Overview
Up close, mondo grass is a low mound of narrow, arching blades, each a slim strap of deep, glossy green that bends over at the tip. It looks like a fine lawn but is no grass at all: it is Ophiopogon japonicus of the asparagus family, an East Asian evergreen. The blades rise in dense little tufts and travel on short underground stems until they pack into an even, close-knit mat.
The foliage carries its darkest green in shade, a rich, cool color that holds through the year in mild climates, and the clumps stay firm through drought once rooted. Down among the crowded blades in summer sit tiny flowers of white to soft lilac, half-hidden and easy to miss. In their place come small, round berries of a clear, striking blue.
The blades gain ground only inch by inch, since mondo grass is a slow spreader that widens on short rhizomes. A fresh planting stays a scatter of separate green tufts for a while, but in time those tufts touch, merge, and settle into one soft, dark carpet.
Care
The short version: part to full shade, in moist but well-drained soil, with steady water while the blades take root and very little feeding after that.
Light
Mondo grass holds its deepest dark green in part to full shade, where the slim blades take on their richest color. It will grow in full sun with extra water, but hot direct sun bleaches the green and scorches the fine tips. Dappled light under trees suits the foliage best.
Water
Keep the soil consistently moist while the blades root in, watering every 5 to 10 days as the weather asks. Once settled, the tufts ride out short dry spells, though any planting in sun draws more water. Aim for moist soil that never sits waterlogged around the roots.
Soil
Average well-drained soil is all the roots ask for, whether clay, loam, or sandy. Steer clear of soggy, poorly drained ground and strongly alkaline sites, both of which rot the roots beneath the blades. A little organic matter worked in gives the tufts a strong start.
Temperature
The dark blades hold through a wide range, from about 0°F to 95°F (-18°C to 35°C). That hardiness is what keeps their green color through the year in zones 7 to 10.
Humidity
Ordinary outdoor humidity suits the foliage, so there is no number to chase. The blades stay healthy in humid and drier climates alike, as long as their moisture and shade needs are met.
Feeding
Mondo grass is a light eater that wants very little feeding. One light application of balanced fertilizer in spring covers it, and only if the tufts look like they want a boost.
Pruning
Mondo grass is low maintenance, needing just one grooming a year. Shear or mow the tattered old blades back in late winter or early spring before the fresh green pushes up, which also strips out overwintering scale.
Repotting
The tufts rarely need lifting and fill in best when left in place. Divide and replant the clumps only when the center thins to bare soil or the crowded blades lose their vigor.
Size & spacing
The tufts of blades reach 6 to 12 inches (15 to 30 cm) tall and spread about the same, so set divisions roughly 6 to 12 inches (15 to 30 cm) apart. Closer spacing lets the blades meet sooner, a help given how slowly the clumps creep.
When to plant
Mondo grass is hardy in zones 7 through 10 and goes in when the soil is workable. Set new tufts out in spring after frost, or in fall, and watch for the small hidden flowers among the blades around June and July.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring after frost, or fall
- Harvest: Summer (about June to July)
Hardiness
USDA hardiness zones: 7–10
Temperature: down to -18°C
Troubleshooting
Mondo grass seldom falters, but a few troubles show in the blades and roots when the site is wrong. Most trace to too much sun, too much water, or the long wait while the tufts spread. Match what you see below and shift the conditions.
Tufts turning yellow and thin over wet roots
The dark tufts fade to yellow and grow sparse and see-through when root rot takes hold in soggy soil, a decline that strongly alkaline ground only deepens. Lift a clump and the story is in the roots: sound ones stay pale and firm, while rotted ones turn dark and mushy to the touch. Sharper drainage, a lighter watering hand, and replanting the firm survivors in well-drained soil laced with organic matter bring the green back.
Fix:
- Improve drainage and stop overwatering
- Replant in well-drained soil amended with organic matter
- Remove and discard severely rotted clumps
Open soil showing between the young tufts
Ribbons of bare earth linger between the fresh tufts because mondo grass is a slow grower, inching outward on short underground rhizomes that need several seasons to weave the blades into one seamless mat. Set the divisions closer and the dark tufts touch sooner. A blanket of mulch over the open soil and steady moisture at the roots draw the clumps together faster.
Fix:
- Be patient; allow several seasons for clumps to knit together
- Space divisions more closely for faster coverage
- Mulch between plants and weed regularly until the mat closes in
- Keep soil evenly moist to encourage establishment
Blades bleached pale and scorched at the tips
Under hot, direct sun the deep green washes out to a pale yellow-green and the slender tips crisp and brown, a fading most pronounced in the fierce heat of the Deep South. Set in filtered sun through full shade, the narrow blades hold their darkest, glossiest green. In an open spot, extra water keeps the color from bleaching away.
Fix:
- Provide afternoon shade or relocate to part to full shade
- Increase watering for plants grown in full sun
- Site in filtered sun to shade where foliage stays darkest
Blades left ragged and pocked by pests
Torn, ragged holes down the blades and glistening slime trails across them are the mark of slugs and snails, while tiny hard bumps clamped tight to the leaf surface are scale insects such as false oleander or fern scale. Pick or bait the slugs off the leaves. Shear the worst-pocked foliage in late winter to strip out the scale, and a 2 percent horticultural oil spray coats and clears any bumps that cling on.
Fix:
- Hand-pick or bait for slugs and snails
- Shear and dispose of infested foliage in late winter to reduce scale
- Apply a 2 percent horticultural oil spray for scale if needed
Toxicity
Reassuring news for pet owners and parents: mondo grass is safe. Neither its slim green blades nor its blue berries appear on the ASPCA toxic-plant lists, and for all its lily-family ties it is nothing like the dangerous true lilies. A large mouthful of any leaf may unsettle a stomach, but there is no real poison in the plant.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
A cat can chew the slim green blades of mondo grass with no harm, since the plant sits nowhere on the ASPCA toxic list. A blade or two passes without trouble, though a big mouthful of the foliage might bring a little drool or a brief upset stomach.
Dogs None
A dog nosing through the dark tufts of mondo grass is in no danger, as the plant carries no harmful toxin. The most an eager chewer risks from a large helping of blades is mild, passing tummy trouble.
Horses Safe
The narrow green blades of mondo grass hold no poison for a grazing horse. As with any large mouthful of lush foliage, an oversized helping could loosen the gut for a day or so.
Rabbits Safe
A rabbit can nibble the fine blades of mondo grass safely, since not one part holds a harmful compound. Keep the portions small, because too much of any fresh green can leave a rabbit with a soft stomach.
Livestock Safe
Cattle, goats, and sheep grazing the grassy tufts of mondo grass face no poison from it. Only an unusually large mouthful of the foliage might bring mild digestive upset.
Birds Safe
Birds, backyard hens included, can peck at the blades and the small blue berries of mondo grass without harm. Neither foliage nor fruit poses any poisoning risk to them.
People Safe
Mondo grass grows for its dark green looks rather than the table, yet its blades and blue berries will not poison a person who tastes them. A child faces no real hazard past the mild upset that follows eating a lot of any leaf.
No special handling required. It is an outdoor groundcover and is not among the truly toxic lilies; mild GI upset is possible only if large amounts are eaten.
Varieties
A few selections turn up far more than the rest, ranging from ankle-high dwarfs to a near-black cousin. These are the ones worth telling apart by leaf and color.
'Nana' / 'Kyoto Dwarf' (Dwarf Mondo Grass)
A miniature form whose tufts rise only about 2 to 4 inches tall and creep along slowly, low enough to stand in for a lawn or thread its fine blades through the joints between stepping stones.
'Gyoku Ryu'
A compact dwarf whose short blades pack into dense, low tufts of dark green, grass-like foliage.
Black Mondo Grass (Ophiopogon planiscapus 'Nigrescens')
A related species rather than true O. japonicus, set apart by narrow blades of near-black purple that throw a stark, dark note of contrast into a planting.
Lilyturf (Liriope) - look-alike, not the same plant
A separate genus mistaken for it at a glance, though Liriope shows broader leaves, flower spikes lifted clear above the foliage, and black berries, while mondo grass keeps narrower blades, flowers tucked out of sight, and blue berries.
How to propagate
Mondo grass is multiplied by teasing established clumps of blades apart rather than from seed, an easy job for any gardener.
DivisionEasy
Spring or early in the growing season · Slow; may take years to fill large areas
More mondo grass comes from pulling a clump apart rather than from seed. Lift a full clump in spring or early in the growing season and tease it into sections, each keeping a handful of pale roots and several dark green blades. The pieces take root without fuss but creep outward slowly, so a broad sweep of blades still needs years to fill in.
Myths
Mondo grass is a true grass.
The slim, arching blades only mimic a grass. Mondo grass is Ophiopogon japonicus in the asparagus family, so it is grass-like in the leaf yet not a grass at all. It is also a plant apart from the similar-bladed lilyturf (Liriope) that so often stands in for it in the eye.