Walk into any garden center and you will find these two sold side by side, often mislabeled, and even seasoned landscapers mix up the names. The mondo grass vs monkey grass question matters because although the two look nearly identical at a glance — both are clumping, grass-like evergreen groundcovers with strappy leaves — they behave very differently in the ground, and planting the wrong one for your spot leads to years of frustration. Neither is a true grass; both are members of the lily family relatives. The short version: mondo grass (Ophiopogon) is smaller, slower, and more refined, while monkey grass (Liriope) is larger, tougher, and more aggressive. Which you want depends entirely on the job you need it to do.
What Each Plant Actually Is
Monkey grass is the common name for Liriope, most often Liriope muscari (the clumping type) or Liriope spicata (the spreading type). It forms tufts of dark green, strap-like leaves 12 to 18 inches tall and produces showy spikes of purple or white flowers in late summer that rise above the foliage like little grape hyacinths.
Mondo grass is Ophiopogon japonicus. Its leaves are finer, darker, and shorter — the standard variety stays around 6 to 10 inches, and dwarf mondo (Ophiopogon japonicus ‘Nana’) tops out at just 2 to 4 inches. Its flowers are small, often hidden down in the foliage, and far less showy than Liriope’s. Mondo has a softer, more turf-like, almost mossy appearance, which is why designers reach for it as a lawn substitute in shade.
The Key Differences at a Glance
Here is the head-to-head that actually decides your choice:
- Size: Monkey grass is taller (12-18 in) and coarser; mondo grass is shorter (2-10 in) and finer.
- Flowers: Monkey grass has prominent purple/white flower spikes above the leaves; mondo grass has small, hidden flowers.
- Leaf color/texture: Monkey grass leaves are wider and can be variegated; mondo leaves are narrower, darker green (or near-black in ‘Nigrescens’).
- Spread: Spreading Liriope (L. spicata) is aggressive via runners; clumping Liriope stays put; mondo spreads slowly by stolons and is easy to control.
- Berries: Both form small berries, but Liriope’s are more visible.
- Growth rate: Monkey grass establishes and fills in faster; mondo is slower.
The single most useful tell in the field: if it has tall flower spikes standing above the leaves, it is monkey grass. If the plant is very short and turf-like with a fine texture, it is mondo.
Size and Growth Habit Compared
This is where the choice usually gets made. Monkey grass is the bigger, bolder plant — it makes a substantial border, a solid edging along a walk, or a coarse groundcover that reads clearly from a distance. Because it grows faster and larger, it fills a bed sooner and stands up to being seen from the street.
Mondo grass is the miniature. Dwarf mondo in particular is prized for tight, low, tidy applications — filling the gaps between stepping stones, edging a formal path with a crisp low line, or carpeting a shady area where you want the look of a fine lawn you never mow. Regular mondo makes a dense, dark, low groundcover. If you want height and presence, choose monkey grass; if you want low, fine, and refined, choose mondo.
Spreading Behavior and Control
Do not overlook this difference, because it causes the most regret. Spreading monkey grass, Liriope spicata, travels underground by rhizomes and will march into lawns and neighboring beds — great for covering a big bank fast, a nuisance in a tidy border. Clumping monkey grass, Liriope muscari, stays in well-behaved tufts and is the one to plant where you want defined edging that will not run.
Mondo grass spreads slowly by short stolons and is generally easy to keep in bounds; it knits together over time without invading. So if containment matters, clumping Liriope or mondo are your friends, and spreading Liriope is the one to install only where you actually want it to take over.
Growing Conditions and Care
Both are famously low-maintenance and share broad tolerances, which is why they are so popular. Both prefer part shade to full shade, though monkey grass tolerates more sun than mondo, which scorches in hot afternoon sun. Both handle a range of soils as long as drainage is decent, and both are drought-tolerant once established.
Cold hardiness differs slightly. Liriope is generally hardy in USDA zones 5 to 10, making it the better pick in colder regions, while mondo grass is happiest in zones 6 or 7 through 11 and less reliable in hard winters. Neither needs mowing, but many gardeners shear old, tattered monkey grass foliage down to a couple of inches in late winter before new growth to refresh it; mondo rarely needs this. Both are easily propagated by dividing clumps in spring.
Planting and Establishing Either One
Both plants go in the ground the same way, and getting the spacing right up front saves you from a patchy bed or an overcrowded one. Plant in spring or early fall so the roots establish before extreme heat or cold. For monkey grass, space clumps 8 to 12 inches apart for a solid border within a season or two; for standard mondo, 6 to 8 inches; and for dwarf mondo used as a carpet or between pavers, 4 to 6 inches. Dig each hole as deep as the root ball and twice as wide, set the crown at soil level, backfill, and water in.
Mulch lightly to hold moisture and suppress weeds while the plants knit together, and keep the soil consistently moist for the first few weeks — this is the one period when both plants actually need attention. After establishment, both are drought-tolerant and largely fend for themselves. Because both spread by division, you can buy a few plants and split them every couple of years to fill a large area for free, which is how many gardeners cover big shady beds on a budget.
Common Problems and Pests
Neither plant is fussy, but a few issues crop up. The most common with monkey grass is crown rot or root rot in soil that stays waterlogged, so drainage matters more than watering frequency. Both can show leaf scorch — brown, crispy tips — when planted in too much hot sun, especially mondo, which is the more shade-demanding of the two. Slugs and snails occasionally chew the foliage in damp, shady spots, and in the Southeast, Liriope can suffer from a fungal leaf-spot disease that shows as brown streaks, usually cured by shearing the old foliage in late winter and improving air circulation.
The biggest “problem” is not a pest at all — it is planting spreading Liriope spicata where you did not want a spreader, then spending years pulling its runners out of the lawn. Read the label and confirm you are buying the clumping Liriope muscari for tidy borders. Mondo grass rarely causes any of these headaches, which is part of its appeal in refined, low-maintenance designs where you want the plant to stay exactly where you put it.
Which One Should You Plant?
Match the plant to the job. Choose monkey grass (Liriope muscari) when you want a substantial border or edging with attractive summer flowers, a plant that fills in quickly, and better cold hardiness — it is the workhorse for defining beds and lining walks in most of the country. Choose spreading Liriope spicata only for erosion control on a bank or to blanket a large area fast where its running habit is a feature, not a bug.
Choose mondo grass when you want something low, fine-textured, and refined — dwarf mondo between pavers, along a formal path, or as a no-mow lawn substitute in shade, and regular or black mondo for a dark, tidy, low groundcover. In warm zones 7 and up, mondo shines; in colder zones, lean toward Liriope. If you still cannot decide, remember the simple rule: monkey grass for height and flowers, mondo grass for a low, lush, lawn-like carpet. Get that match right and either one will give you a decade of tough, evergreen, nearly effortless groundcover.
