Monkey Grass Plant Profile

Three Types, Three Different Uses

Close up of black monkey grass used in a landscape

David Beaulieu

"Monkey grass" is a common name heard most often in the South. It can refer to any of three different plants: one type of Ophiopogon (black mondo grass) and two types of Liriope. While they're used in similar ways, there are important differences between these three perennials that you should be aware of before making a selection. All are good substitutes for shade-tolerant, semi-evergreen ornamental grasses. All have few pest and disease problems, but you may need to protect them against slugs.

Black Mondo Grass

Black mondo grass (Ophiopogon planiscapus 'Nigrescens') isn't a true grass; true grasses belong to the Poaceae family. Black mondo grass is, instead, a tuberous-rooted perennial in the lily family. It's a stemless plant on which the leaves sprout from the ground in clumps. In summer, a single flower stalk sprouts, carrying small, bell-shaped, pinkish flowers. This grass-like plant is often used as a ground cover for semi-shady areas, or in the front of a border or as an edging plant. It's common in rock gardens and valued for its unusual, black foliage. It makes for a great contrast with a plant like Sedum rupestre 'Angelina.'

Botanical Name Ophiopogon planiscapus 'Nigrescens'
Common Names  Monkey grass, black mondo grass
Plant Type Herbaceous perennial
Mature Size 9 to 12 inches tall, with a similar spread
Sun Exposure Full sun to partial shade
Soil Type Moist but well-drained
Soil pH Slightly acidic (5.5 to 6.5)
Bloom Time July to August
Flower Color Pink
Hardiness Zones 6 to 9
Native Area Japan

How to Grow Black Mondo Grass

Space plants 4 inches apart in moist, well-drained soil. Immediately top-dress them with compost to retain soil moisture. No seasonal feeding is needed. Each spring, remove old foliage from around the plants. Where you want to thin the plants or propagate them, lift and divide the roots in spring.

Light

Black mondo grass tolerates a wide range of sun conditions, but the warmer the climate, the more shade is of benefit.

Soil

It prefers moist but well-drained soil with ample organic material. The ideal pH is somewhat acidic.

Water

Mondo grass must be kept consistently moist but not soggy. The hotter the temperature, the more water is required.

Temperature and Humidity

Ideal growing conditions are warm but not hot. It tolerates a wide range of humidity levels if the soil is kept moist. Slugs are a problem in moist climates.

Fertilizer

Black mondo grass doesn't require much feeding. A single top-dressing of compost in the spring will suffice.

Propagating Black Mondo Grass

Black mondo grass is propagated by dividing the fibrous roots in spring.

  1. Use a garden fork to pry clumps up from the ground.
  2. Use your hands to tease apart groups of roots, dividing them into sections each containing a few leaves. A knife may be necessary if the roots are thickly entwined.
  3. Cut away any dried or diseased portions of roots.
  4. Replant the clumps 4 inches apart in the garden. If you cannot plant them immediately, keep them moist until planting.

Creeping Liriope

Liriope, another genus commonly known as monkey grass, includes two species: creeping liriope (Liriope spicata) and big blue lilyturf (Liriope muscari). Liriope is in the asparagus family. It has a very similar growth habit and uses to black mondo grass, but it's a slightly taller plant. We will cover L. spicata first.

Botanical Name Liriope spicata
Common Names  Monkey grass, creeping liriope
Plant Type Herbaceous perennial
Mature Size 9 to 18 inches in height with a similar spread
Sun Exposure Full sun to partial shade
Soil Type Average, well-drained
Soil pH Neutral to slightly acidic (6.0 to 7.0)
Bloom Time August to September
Flower Color White to lavender
Hardiness Zones 4 to 10
Native Area China, Japan, Southeast Asia

How to Grow Creeping Liriope

Plant creeping liriope in any medium, well-drained soil, spacing the plants 12 to 18 inches apart; they'll quickly fill in gaps. Poor soil should be amended with compost. Feeding is rarely necessary; an annual top-dressing of compost may be helpful. Once established, water the plants deeply once a week. Where division is necessary to thin out dense clumps or propagate plants, do it in the early spring. The foliage can be mown down with a lawnmower set at a high cutting length when the growing season is over (in warmer climates, the plant may be evergreen).

Light

Creeping liriope tolerates a wide range of sun conditions, but the warmer the climate, the more that shade is of benefit.

Soil

This plant prefers an average, well-drained soil that has ample organic material. The ideal pH is somewhat acidic.

Water

Creeping liriope performs ideally if it receives a good, heavy watering each week, but once established it has good drought tolerance.

Temperature and Humidity

Ideal growing conditions are warm but not hot. This plant tolerates a wide range of temperatures and humidity levels.

Fertilizer

Creeping liriope does not require much feeding. A single top-dressing of compost in the spring will suffice.

Propagating Creeping liriope

Creeping liriope is usually propagated by lifting and dividing the fibrous roots in spring.

  1. Use a garden fork to pry up clumps up.
  2. Use your hands to tease apart groups of rhizomes, dividing them into sections.
  3. Cut away any dried or diseased root portions.
  4. Replant the clumps 12 to 18 inches apart.

Big Blue Lilyturf

Big blue lilyturf has similar growing requirements to creeping liriope, so we'll restrict ourselves to exploring how the two plants differ and why you'd choose one over the other depending on your landscaping needs.

Botanical Name Liriope muscari
Common Names  Monkey grass, big blue lilyturf
Plant Type Herbaceous perennial
Mature Size 9 to 18 inches in height with a similar spread
Sun Exposure Full sun to partial shade
Soil Type Average, well-drained
Soil pH Neutral to slightly acidic (6.0 to 7.0)
Bloom Time August to September
Flower Color Lavender
Hardiness Zones 5 to 10
Native Area China, Japan, Southeast Asia

How Big Blue Lilyturf Differs From Creeping Liriope

Creeping liriope is slightly hardier, so it can be a better choice for Northern gardeners. Its blade-shaped leaves are narrower than big blue lilyturf's. Both produce flower spikes, but those on big blue lilyturf are showier because they protrude farther enough up out of the foliage to be visible from afar.

"Creeping" liriope received its common name from the fact that it spreads via underground rhizomes. By contrast, big blue lilyturf forms well-behaved clumps. Because creeping liriope can easily spread out of control under the right conditions, it's ill-suited for use as an edging plant. But this same quality makes it a great ground cover for spots where you want a plant that: