Ornamental · Asparagaceae
Mondo Grass
Ophiopogon japonicus
Hand it shade and steady moisture, and mondo grass settles into a soft, dark green carpet that barely asks a thing.
Partial shade
Every 5–10 days
USDA 7–10
6–12 in · 15–30 cm
Overview
It sure looks like a fine, dark green lawn, but mondo grass isn't a grass at all. It's Ophiopogon japonicus, part of the asparagus family, native to East Asia and grown as an evergreen groundcover. Those narrow, arching blades bunch into low tufts and travel on short underground stems until they've built a dense, even mat.
So why do gardeners keep reaching for it? Because it thrives right where a lawn throws in the towel. It takes shade that most plants just can't stand, keeps its color all year in mild climates, and shrugs off drought once it's dug in. Come summer, tiny white to lilac flowers tuck down among the leaves, and little blue berries follow.
The one thing it wants from you is patience. Mondo grass is a slow spreader, so a fresh planting takes its time closing the gaps, but stick with it and you'll end up with one of the easiest carpets going.
Care
The short version: part to full shade, moist but well-drained soil, steady water while it's settling in, and hardly any feeding once it's established.
Light
Mondo grass is happiest in part to full shade, where the blades keep their richest dark green. It'll take full sun too, but only if you water it more, since hot direct sun tends to bleach or scorch the leaves. Dappled light under some trees? That's the sweet spot.
Water
Keep the soil consistently moist while the plants are settling in, watering every 5 to 10 days depending on the weather. Once they're dug in, they can handle a short dry spell, though anything in the sun gets thirstier. You want moist soil, just never soggy.
Soil
Regular well-drained soil is really all it asks for, clay, loam, or sandy, take your pick. What you don't want is soggy, poorly drained ground or a strongly alkaline spot, because either one sets it up for root rot. Mixing in a little organic matter gives it a nice head start.
Temperature
Mondo grass is tough over a big range, from around 0°F to 95°F (-18°C to 35°C). That hardiness is what keeps its color going all year in zones 7 to 10.
Humidity
Regular outdoor humidity suits it just fine, so there's no number to worry about. It settles in whether the air's humid or on the dry side, as long as its moisture and shade needs are covered.
Feeding
It's a light eater that wants very little feeding. One light dose of balanced fertilizer in spring does the trick, and only if the planting looks like it could use a lift.
Pruning
Mondo grass is low maintenance and only needs a single tidy-up a year. Shear or mow the ratty old foliage back in late winter or early spring before the new growth comes up, which handily sets back scale too.
Repotting
Clumps hardly ever need lifting, so it's usually best to just let them fill in. Divide and replant only when the center thins out or the clump gets crowded and loses steam.
Size & spacing
Plants get to 6 to 12 inches (15 to 30 cm) tall and spread about the same, so set your divisions roughly 6 to 12 inches (15 to 30 cm) apart. Space them closer and the gaps close up sooner, which helps given how slowly it creeps.
When to plant
Mondo grass is hardy in zones 7 through 10, and it goes in whenever the soil's workable. Pop new plants in during spring once the frost has cleared, or in fall, and keep an eye out for those 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 barely ever acts up, but a few things can go sideways when the spot doesn't quite fit. Nearly all of it comes back to too much sun, too much water, or just being impatient while it fills in. Find what matches below and tweak the conditions.
Clumps going yellow and thin in soggy ground
If your clumps turn yellow and start thinning out, it's usually root rot from soil that stays too wet, and strongly alkaline ground doesn't help either. Want to know for sure? Dig down and squeeze a root, because a rotted one feels dark and soft while a healthy one stays firm. Sort out the drainage, back off the watering, and give the survivors a fresh home in well-drained soil worked with some 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 while it fills in
Still seeing soil between your new plants? That's just mondo grass being a slow grower, since it only creeps along on short rhizomes and takes a few seasons to knit into a solid mat. Setting the divisions a bit closer gets you cover sooner. Meanwhile, mulch the open ground, stay on top of the weeds, and keep the soil evenly moist so the clumps meet up 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
Pale, scorched leaves in too much sun
When the color drains out of the leaves and the tips look burnt, too much hot, direct sun is the culprit, and it's rougher still in the Deep South where the heat really cranks up. The easy answer? Give it filtered sun to full shade and the leaves come right back to their darkest green. And if it has to sit in the open, just water it a little more to take the edge off.
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 blades from little pests
Ragged holes with shiny slime trails? That's slugs and snails having a snack. Little bumps stuck to the blades that don't budge are scale insects, usually false oleander or fern scale. Hand-pick or bait the slugs, and shear off the badly infested foliage in late winter to knock the scale down. If the scale's really digging in, a 2 percent horticultural oil spray takes care of it.
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 if you've got pets or kids around: mondo grass is safe. It isn't on the ASPCA toxic-plant lists, and even with its lily-family relatives, it's nothing like those dangerous true lilies. Sure, eating a big pile of any leaf can upset a stomach, but there's no real poison here to worry about.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cats are just fine around mondo grass, and it isn't on the ASPCA toxic list. A nibble or two won't do a thing, though a big greedy mouthful might leave a cat drooling a little or with a short upset stomach.
Dogs None
Got a dog? No problem sharing the garden with mondo grass. There's nothing toxic in it, so the worst a determined chewer runs into is a bit of mild, short-lived tummy trouble after eating a lot.
Horses Safe
Horses grazing near mondo grass have nothing to worry about, because it isn't poisonous. Like any big mouthful of fresh greens, though, an unusually large helping might loosen the gut for a day.
Rabbits Safe
Rabbits can nibble mondo grass safely, since not one part of it holds anything harmful. Just keep the treats small, because too much of any new green tends to give a rabbit a soft stomach.
Livestock Safe
Cattle, goats, and sheep are all safe around mondo grass, which just isn't a toxic plant. A grazing animal might only get mild digestive upset after packing away an unusually large amount.
Birds Safe
Birds, backyard hens included, can peck away at mondo grass and its blue berries with no trouble at all. There's simply no poisoning risk for them here.
People Safe
Mondo grass is a looker, not a snack, but it won't poison anyone who tastes it either. Kids aren't in any real danger past the mild upset you'd get 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 handful of these show up way more than the rest, from ankle-high dwarfs to a nearly black cousin. Here's how to tell the main ones apart.
'Nana' / 'Kyoto Dwarf' (Dwarf Mondo Grass)
This little dwarf tops out at only about 2 to 4 inches tall and creeps along slowly, which is exactly why folks love it as a tiny lawn stand-in and for tucking between stepping stones.
'Gyoku Ryu'
This compact dwarf pick clumps up into dense, low tufts of dark green, grass-like foliage.
Black Mondo Grass (Ophiopogon planiscapus 'Nigrescens')
It's actually a cousin rather than true O. japonicus, and people grow it for that near-black purple foliage that throws great color contrast into a planting.
Lilyturf (Liriope) - look-alike, not the same plant
It's a whole different genus that trips up loads of gardeners, since Liriope has wider leaves, showy flower spikes standing above the foliage, and black berries, while mondo grass keeps narrower leaves, hidden flowers, and blue berries.
How to propagate
Making more mondo grass is just a matter of splitting up clumps you already have, not fussing with seed, and honestly it's an easy job for anybody.
DivisionEasy
Spring or early in the growing season · Slow; may take years to fill large areas
Want more mondo grass? Just split up what you've got instead of messing with seed. Dig up a big clump in spring or early in the growing season and pull it apart into sections, holding on to as many roots as you can plus a few leaves on each piece. The new bits root easily but travel slowly, so a wide patch will still want years to fill in.
Myths
Mondo grass is a true grass.
Nope, it just looks the part. Mondo grass is really Ophiopogon japonicus in the asparagus family, so it's grass-like to look at but not actually a grass. And it's its own plant, separate from that look-alike lilyturf (Liriope) that gardeners are always mixing it up with.