Ornamental · Asparagaceae
Mondo Grass
Ophiopogon japonicus
Give it shade and steady moisture, and mondo grass settles into a soft, dark green carpet that asks for almost nothing.
Partial shade
Every 5–10 days
USDA 7–10
6–12 in · 15–30 cm
Overview
Mondo grass looks like a fine, dark green lawn, but it isn't a grass at all. It's Ophiopogon japonicus, a member of the asparagus family, native to East Asia and grown as an evergreen groundcover. The narrow, arching blades form low tufts that spread on short underground stems into a dense, even mat.
Gardeners reach for it because it thrives where lawns struggle. It takes shade that most plants can't handle, holds its color through the year in mild climates, and shrugs off drought once it's settled in. Tiny white to lilac flowers hide down among the leaves in summer, followed by small blue berries.
The one thing it asks for is patience. Mondo grass is a slow spreader, so a fresh planting takes its time to close the gaps, but once it does, it makes one of the most carefree carpets you can grow.
Care
The short version: part to full shade, in moist but well-drained soil, with steady water while it gets established and very little feeding after that.
Light
Mondo grass does best in part to full shade, where the blades stay their richest dark green. It will take full sun, but only with extra water, and hot direct sun tends to bleach or scorch the foliage. Filtered light under trees suits it perfectly.
Water
Keep the soil consistently moist while plants establish, watering every 5 to 10 days depending on weather. Once settled, mondo grass handles short dry spells, though anything grown in sun needs more to drink. The soil should stay moist but never waterlogged.
Soil
Average well-drained soil is all it asks, whether clay, loam, or sandy. The thing to avoid is soggy, poorly drained ground or a strongly alkaline site, both of which invite root rot. Working in some organic matter gives it a good start.
Temperature
Mondo grass is tough across a wide range, from about 0°F to 95°F (-18°C to 35°C). That hardiness is what lets it hold its color through the year in zones 7 to 10.
Humidity
Ordinary outdoor humidity suits it fine, so there's no number to chase. It adapts to humid and drier climates alike as long as its moisture and shade needs are met.
Feeding
This is a light eater that needs very little feeding. A single light application of balanced fertilizer in spring covers it, and only if the planting looks like it wants a boost.
Pruning
Mondo grass is low maintenance and needs only one tidy-up a year. Shear or mow the tattered old foliage back in late winter or early spring before new growth pushes through, which also helps knock back scale.
Repotting
Clumps rarely need lifting and are best left to fill in. Divide and replant only when the center thins or the clump grows crowded and loses vigor.
Size & spacing
Plants 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 closes the gaps sooner given how slowly it creeps.
When to plant
Mondo grass is hardy in zones 7 through 10 and goes in the ground when the soil is workable. Set new plants out in spring after the frost has passed, or in fall, and look for its hidden summer flowers 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 rarely gives trouble, but a few problems show up where the site doesn't suit it. Most trace back to too much sun, too much water, or simple impatience while it fills in. Match what you see below and adjust the conditions.
Yellowing, thinning clumps in wet ground
When clumps yellow and thin out, the trouble is usually root rot from soggy soil, and strongly alkaline ground makes it worse. Dig down and check: rotted roots feel dark and soft instead of firm. Improve the drainage, ease off the water, and replant survivors in well-drained soil amended with organic matter.
Fix:
- Improve drainage and stop overwatering
- Replant in well-drained soil amended with organic matter
- Remove and discard severely rotted clumps
Bare gaps and weeds between slow-spreading clumps
Mondo grass is a slow grower that creeps along on short rhizomes, so a new planting can take several seasons to knit into a solid mat. Space the divisions closer together for quicker cover, then mulch and weed the open ground until the clumps meet. Steady moisture during this stretch helps them fill in 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
Bleached or scorched leaves in hot sun
Too much hot, direct sun drains the color from the foliage and can scorch the tips, especially in the Deep South where the heat is fierce. Filtered sun to full shade keeps the leaves their darkest green. If you must grow it in the open, give it extra water to take the edge off the heat.
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
Chewed, ragged foliage from pests
Ragged holes and slime trails point to slugs and snails, while small immobile bumps on the blades are scale insects such as false oleander or fern scale. Hand-pick or bait the slugs, and shear off heavily infested foliage in late winter to knock back the scale. A 2 percent horticultural oil spray clears up a stubborn scale problem.
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
Good news for pet owners and parents: mondo grass is safe. It isn't on the ASPCA toxic-plant lists, and despite its lily-family ties it's nothing like the dangerous true lilies. Eating a large amount of any leaf can upset a stomach, but there's no real poison here.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Mondo grass is safe around cats and isn't on the ASPCA toxic list. A cat that nibbles a few blades is fine, though gulping a big mouthful might bring on a little drool or a brief upset stomach.
Dogs None
Dogs can share a garden planted with mondo grass without any worry. It carries no dangerous toxins, and the worst a curious chewer faces is mild, passing tummy trouble from eating a large amount.
Horses Safe
Horses grazing near mondo grass have nothing to fear, since the plant is not poisonous. As with any rich mouthful of greenery, a very large helping could loosen the gut for a day or so.
Rabbits Safe
Rabbits can browse mondo grass safely; none of its parts hold a harmful compound. Keep treats modest, as too much of any new green can leave a rabbit with a soft stomach.
Livestock Safe
Cattle, goats, and sheep are in no danger from mondo grass, which isn't a toxic plant. A grazing animal might get mild digestive upset only after eating an unusually large quantity.
Birds Safe
Birds, including backyard hens, can peck at mondo grass and its blue berries without harm. The plant poses no poisoning risk to them.
People Safe
Mondo grass is grown as an ornamental, not for the table, but it won't poison anyone who tastes it. There's no real hazard to children beyond the mild upset that comes from 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 knowing apart.
'Nana' / 'Kyoto Dwarf' (Dwarf Mondo Grass)
A very compact dwarf form only about 2 to 4 inches tall that creeps along slowly, prized as a tiny lawn substitute and for tucking between stepping stones.
'Gyoku Ryu'
A compact dwarf selection that forms dense, low tufts of dark green, grass-like foliage.
Black Mondo Grass (Ophiopogon planiscapus 'Nigrescens')
A related species rather than true O. japonicus, grown for its striking near-black purple foliage that throws color contrast into a planting.
Lilyturf (Liriope) - look-alike, not the same plant
A different genus that fools many gardeners, since Liriope carries wider leaves, showy flower spikes held above the foliage, and black berries, while mondo grass keeps narrower leaves, hidden flowers, and blue berries.
How to propagate
Mondo grass is multiplied by splitting up established clumps rather than from seed, and it's an easy job for any gardener.
DivisionEasy
Spring or early in the growing season · Slow; may take years to fill large areas
Division is the standard way to make more mondo grass. Lift a large clump in spring or early in the growing season and split it into sections, keeping as many roots as you can along with several leaves on each piece. The new divisions take hold easily but spread slowly, so a wide patch can take years to fill in.
Myths
Mondo grass is a true grass.
It only looks the part. Mondo grass is Ophiopogon japonicus in the asparagus family, grass-like in appearance but not a grass at all. It's also a separate plant from the similar-looking lilyturf (Liriope), which gardeners often mix it up with.