Ornamental · Asparagaceae
Mondo Grass
Ophiopogon japonicus
Hand it shade and steady moisture, and mondo grass rolls out 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 reads as a fine, dark green lawn, yet it never joined the grass club. It is Ophiopogon japonicus, a proud member of the asparagus family from East Asia, grown as an evergreen groundcover. The narrow, arching blades bunch into low tufts and march along on short underground stems until they pack down into a dense, even mat.
Growers keep reaching for it because it powers ahead where lawns give up. It laps up shade that flattens most plants, holds its color the year round in mild climates, and rides out drought once it digs in. Come summer, tiny white to lilac flowers duck down among the leaves, and small blue berries follow behind.
The one thing it demands is patience. Mondo grass is a slow spreader, so a fresh planting takes its sweet time closing the gaps, but stick with it and the payoff is one of the most rewarding, carefree carpets going.
Care
The short version: hand it part to full shade and moist but well-drained soil, keep the water flowing while it settles in, and feed it barely at all once it's rooted.
Light
Mondo grass thrives in part to full shade, where the blades pump out their richest dark green. It will handle full sun, but only with extra water, since hot direct sun tends to bleach or scorch the foliage. Dappled light under trees suits it perfectly.
Water
Keep the soil consistently moist while plants settle in, watering every 5 to 10 days as the weather dictates. Once rooted, mondo grass shrugs off short dry spells, though anything in sun drinks more. Aim for moist soil that never turns waterlogged.
Soil
Ordinary well-drained soil is all it wants, clay, loam, or sandy, take your pick. Steer well clear of soggy, poorly drained ground or a strongly alkaline site, because either one invites root rot. Fork in a little organic matter to launch it strong.
Temperature
Mondo grass is a real trooper across a wide range, from about 0°F to 95°F (-18°C to 35°C). That hardiness is exactly what keeps its color firing through the year in zones 7 to 10.
Humidity
Everyday outdoor humidity keeps it happy, so there's no number to chase. It settles into humid and drier climates alike, as long as its moisture and shade needs get met.
Feeding
This is a light eater that wants very little feeding. One light hit of balanced fertilizer in spring covers it, and only when the planting looks like it's begging for a lift.
Pruning
Mondo grass is low maintenance and asks for just one tidy-up a year. Shear or mow the tattered old foliage back in late winter or early spring before new growth surges up, which knocks back scale as a handy bonus.
Repotting
Clumps rarely need lifting and do best left to fill in. Divide and replant only once the center thins out or the clump crowds up and loses steam.
Size & spacing
Plants shoot to 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. Pack them closer and the gaps close sooner, which pays off given how slowly it creeps.
When to plant
Mondo grass powers along outdoors in zones 7 through 10 and drops into the ground whenever the soil is workable. Plant it out in spring once the frost clears, or in fall, and keep watch 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 keeps its head down and rarely acts up, though a few snags surface when the site doesn't fit. Nearly all of them trace to too much sun, too much water, or a bit of impatience while it fills in. Match what you spot below and dial in the conditions.
Clumps yellowing and thinning in soggy soil
Clumps that yellow and thin out are usually battling root rot in soil that stays too wet, and strongly alkaline ground piles on the trouble. Dig right down and check, because healthy roots stay firm while rotted ones turn dark and mushy. Fix the drainage, dial back the water, and replant the survivors into well-drained soil charged with organic matter to get them roaring again.
Fix:
- Improve drainage and stop overwatering
- Replant in well-drained soil amended with organic matter
- Remove and discard severely rotted clumps
Bare gaps closing up as clumps spread
Hang in there while the gaps close, because mondo grass is a slow grower that travels on short rhizomes and spends a few seasons weaving into a solid mat. Pack the divisions closer together and cover comes on quicker. Mulch the open ground, stay ahead of the weeds, and keep the soil evenly moist to drive the clumps toward each other 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, scorched blades under blazing sun
Blazing, direct sun bleaches the color and scorches the tips, and it hits hardest in the Deep South where the heat really climbs. Good news travels fast here: shift it into filtered sun or full shade and the blades bounce back to their deepest green. Stuck growing it in the open? Pour on extra water and it shakes 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 blades under pest attack
Ragged holes and glinting slime trails give away slugs and snails on the prowl, while tiny fixed bumps clamped to the blades reveal scale insects like false oleander or fern scale. Pick or bait the slugs and they clear out fast. Shear the badly infested foliage in late winter to slash the scale, and hit any stubborn holdouts with a 2 percent horticultural oil spray.
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
Cheerful news for pet owners and parents: mondo grass is safe. It stays clear of the ASPCA toxic-plant lists, and for all its lily-family relatives it acts nothing like the dangerous true lilies. Sure, packing away a big pile of any leaf can rattle a stomach, but there's no real poison lurking here.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cats get the all-clear around mondo grass, which never lands on the ASPCA toxic list. Nibble a blade or two and a cat stays perfectly fine, though wolfing down a big mouthful might spark a little drool or a quick upset stomach.
Dogs None
Dogs can romp through a garden full of mondo grass with zero worry. It packs no dangerous toxins, so even an eager chewer faces nothing worse than mild, passing tummy trouble after eating a big helping.
Horses Safe
Horses grazing beside mondo grass have nothing to fear, because the plant carries no poison. As with any rich mouthful of greens, a really large helping might loosen the gut for a day.
Rabbits Safe
Rabbits can browse mondo grass safely, since not one of its parts holds a harmful compound. Keep the treats modest all the same, because too much of any new green can leave a rabbit with a soft stomach.
Livestock Safe
Cattle, goats, and sheep face no danger from mondo grass, which simply isn't a toxic plant. A grazing animal might pick up mild digestive upset only after eating an unusually large quantity.
Birds Safe
Birds, backyard hens and all, can peck happily at mondo grass and its blue berries with no harm done. The plant hands them zero poisoning risk.
People Safe
Mondo grass grows for show rather than the plate, but it won't poison anyone who takes a taste. 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 way more than the rest, from ankle-high dwarfs to a near-black cousin. These are the ones worth learning to tell apart.
'Nana' / 'Kyoto Dwarf' (Dwarf Mondo Grass)
This tiny dwarf shoots up only about 2 to 4 inches tall and creeps along at a gentle pace, which is why growers snap it up as a miniature lawn substitute and for packing between stepping stones.
'Gyoku Ryu'
This compact dwarf selection builds dense, low tufts of dark green, grass-like foliage.
Black Mondo Grass (Ophiopogon planiscapus 'Nigrescens')
A related species rather than true O. japonicus, it earns a spot for near-black purple foliage that fires striking color contrast into a planting.
Lilyturf (Liriope) - look-alike, not the same plant
A different genus that catches out heaps of gardeners, since Liriope flaunts wider leaves, showy flower spikes standing above the foliage, and black berries, while mondo grass sticks to narrower leaves, hidden flowers, and blue berries.
How to propagate
Mondo grass multiplies by splitting up clumps you already have rather than fussing with seed, and it's an easy, satisfying job for any gardener.
DivisionEasy
Spring or early in the growing season · Slow; may take years to fill large areas
Multiplying mondo grass is a breeze once you split up a clump instead of chasing seed. Dig up a big clump in spring or early in the growing season and pull it apart into sections, hanging on to as many roots as you can plus several leaves per piece. The fresh divisions grab hold with ease but travel slowly, so a wide patch still wants years to fill in.
Myths
Mondo grass is a true grass.
It just pulls off a great impression. Mondo grass is really Ophiopogon japonicus in the asparagus family, which makes it grass-like to look at yet not a grass at all. It also stands apart from the look-alike lilyturf (Liriope) that gardeners keep tangling it up with.