Short answer
Choose liriope if you want a taller, bolder plant with visible flower spikes that can fill larger areas and takes more sun. Choose mondo grass if you want a finer, shorter, slower-growing plant for shady edges and small spaces. Both are evergreen, grass-like groundcovers, and both are widely used under trees.
Are they the same plant?
No, though people often call both “monkey grass” or “lilyturf.” Neither is a true grass. Both belong to the asparagus family (Asparagaceae), and they are different genera:
- Liriope (Liriope muscari and Liriope spicata)
- Mondo grass (Ophiopogon japonicus, plus black mondo grass, Ophiopogon planiscapus ‘Nigrescens’)
Because the common names overlap and nurseries use them loosely, check the botanical name on the tag.
Side-by-side comparison
| Feature | Liriope | Mondo grass |
|---|---|---|
| Height | Roughly 10 to 24 inches, depending on species | Roughly 6 to 12 inches; dwarf types about 2 to 6 |
| Leaves | Wider, straighter, blade-like | Narrower, finer, often darker and more arching |
| Flowers | Purple, lavender or white spikes held above the foliage in summer | Small white or lilac flowers hidden in the foliage |
| Berries | Dark or black berries | Blue berries |
| Light | Full sun to full shade | Prefers part to full shade; protect from harsh afternoon sun |
| Growth habit | L. muscari clumps; L. spicata spreads by runners | Slow-spreading, forming dense tufts or a mat |
| Annual trim | Usually cut back in late winter or early spring | Often needs little or no cutting |
Numbers come from nursery and extension descriptions and vary by cultivar.
Liriope
Liriope is the larger and more upright of the two. Liriope muscari, such as the well-known ‘Big Blue’, grows in neat clumps and produces showy flower spikes. Liriope spicata, sometimes called creeping liriope, is shorter and spreads faster by underground runners.
Pros
- Tolerates a wide range of light, from sun to deep shade, and many soils, and handles heat and some drought once established.
- Fills space faster than mondo grass.
- Visible flowers add late-summer color.
Cons
- Needs an annual haircut to remove tattered winter foliage.
- Creeping liriope can run into lawns and beds, and it is regarded as invasive in some regions (see non-invasive ornamental grasses). Check your local extension office, and use clumping types for tidy borders.
Mondo grass
Mondo grass has a softer, finer texture and stays closer to the ground. It forms dense tufts that look like a carpet over time. Types include standard green mondo grass, dwarf mondo grass, and black mondo grass with nearly black leaves.
Pros
- A fine, neat look that suits edging, paths, between stepping stones and Japanese-style gardens.
- Slow growth and generally less cutting back.
- Dwarf forms stay very low.
Cons
- Slow to fill a large area, which can mean buying many plants.
- Less cold hardy than liriope. One source lists Ophiopogon japonicus as hardy only in zones 7 to 11, and black mondo grass is described as best in protected spots.
Shade and sun tolerance
Both do well in shade, including under trees. Liriope is the more flexible one, and it can also take more sun. Mondo grass generally prefers part to full shade, and leaves can scorch in strong afternoon sun. Neither is built for heavy foot traffic like a lawn, although dwarf mondo grass is sometimes used as a lawn substitute in light-use areas.
Hardiness
Rated zones vary by source and cultivar. Liriope muscari is commonly listed for roughly zones 5 to 10, and L. spicata for roughly zones 4 or 5 to 10 or 11. Mondo grass is generally the less hardy of the two. If you garden in a cold area, liriope is the safer pick; see our guide to ornamental grasses for Zone 5.
Planting and care
- Spacing: about 12 inches apart for clumping types; closer for spreaders or if you want quick coverage.
- Soil: loosen the soil and add organic matter if drainage is poor.
- Watering: water regularly until established, then they are fairly drought tolerant.
- Trimming liriope: cut it back with shears or a mower on a high setting in late winter or early spring, before new growth starts. Mondo grass needs less; see when to cut back mondo grass.
- Dividing: both can be divided in spring to get more plants.
Which should you choose?
- Large shady beds, slopes, or a fast groundcover: liriope (preferably clumping Liriope muscari).
- Tight edging, small gardens, or fine texture: mondo grass.
- Cold climates: liriope, with hardiness checked for your cultivar.
- Dark foliage contrast: black mondo grass in a protected spot.
If neither is quite right, sedges such as Pennsylvania sedge are another groundcover option; see our guide to Carex varieties for shade. For more on this whole category, read our overview of ornamental grasses for shade.