Black Mondo Grass Care (Monkey Grass) - Shiny Plant

Black Mondo Grass Care (Monkey Grass)

Black mondo grass is an ornamental plant grown on the sidewalk. The plant is commonly referred to as “Monkey grass” in the south.

If you call monkey grass it can be either of any three plants- black mondo grass (Ophiopogon) and two types of Liriope.

All these types are semi-evergreen, and shade-tolerant ornamental grasses. These plants do have some pests and diseases problem but they all are susceptible to slugs.

In this article, we’ll discuss Black mondo grass care, propagation, and transplantation.

Black Mondo Grass care

Black Mondo Grass

Black mondo grass isn’t truly grass but it is a rooted perennial plant that belongs to the lily family. True grasses belong to the Poaceae family some examples are pink muhly grass and blue oat fescue grass both ornamental grasses.

This is a stemless plant that sprouts foliage from ground clumps. The plant also features bell-shaped, pinkish flowers in the spring.

This plant is often used as a shade ground cover plant or in front of a border or as an edging plant. The plant makes a good companion with plant-like Sedum repeater ‘Angelina’.

Watch Story: Black mondo Grass: Growing and Caring tips

How to Grow Black Mondo grass from Seeds 

Black mondo grass can be grown from seeds as well as from division. However, most gardeners use division to propagate new plants because this is a slow-growing plant. It takes two to three months to get established, even months to sprout seedlings from seeds.

If you plant them from seeds in spring they may not get hardy or well-established till the winter season. So, the division is the best method to propagate multiple black mondo types of grass.

How to Divide Black Mondo Grass

  • Black mondo grass needs to be divided every two to three years for better airflow between the roots.
  • Take a strong and sharp shovel or spade. Water the plant to make the soil moist.
  • Dig out the plant from the soil. Dig a large area to get the plant out with its root balls. This grass has a strong root connection, it might take time and energy to toss them out.
  • After dipping out, split its clumps into two to three roughly equal parts. It has strong roots, use a sharp gardening shear to cut roots.
  • Wash roots with water to remove soil from them. In the process, if you find damaged roots balls, cut them off. 
  • Plant one part again in the soil and the other parts in a different location where you want to grow a new plant.
  • You can plant them in rows but with space of at least 4 inches between each division.
  • If you want to plant them after some time, keep the roots of the plant in the water to keep them moist. The plant does not get affected till its roots are moist.

Quick Guide

Common NameBlack Mondo Grass, Monkey grass
Scientific NameOphiopogon planiscapus ‘Nigrescens’
Plant typePerennial grass
Mature Size9-12 inches tall and wide
Sun ExposureFull sun to partial shade
Soil TypeMoist, well-drained soil
Soil pH5.5 – 6.5
Bloom TimeJuly to August
Flower ColorPink
Hardiness Zones6 to 9 USDA
Native AreaJapan

Black Mondo Grass Care

Black mondo grass does not need much care, but you have to water and prune them occasionally for continuous growth. Below are ideal conditions for better growth.


Although, Black mondo grass can tolerate both sun and shade. But ideally, the plant should get at least 6 hours of direct sunlight. The shade usually depends on the intensity of sunlight, in hot and warm climates they require more shade. 


This plant does not need much fertile soil. Average, well-drained soil with a layer of organic compost leads to healthy growth. They prefer soil pH to a range between neutral to slightly acidic. 


Most the ornamental grass becomes drought-tolerant once they get established like blue fescue but black mondo grass needs constant water to grow. This plant needs regular water to keep its roots moist. In hot or warm climates, they require more water.

Temperature and Humidity

Black mondo grass can grow in a wide range of climates. However, they prefer to grow in warm but not too hot climates. The plant can tolerate moderate humidity if the soil is moist. 

The plant is constantly reported to attack by slugs in humidity conditions. If you live in a high humid zone, plant them in partial shade with a minimum of 4 inches of gap between each plant for better airflow.


Most ornamental plants do not require fertilization. A layer of compost in the spring is enough for its growth. Adding fertilizer to the plant, especially conventional fertilizer, increases nitrogen levels in the soil.

This results in excessive growth of foliage and not flowers, which leads to overgrown and unflowered plants. You can know if the plant needs fertilizer or not by simply doing a soil test.

If you want to use conventional fertilizer, use water-soluble 10-10-10 fertilizer on ornamental grasses, but in limit.


How to Prune black mondo grass

Pruning is an important aspect of the growth of the plant. Occasionally, check the plant if it has some dry or yellow foliage or not. Cut off these dry leaves to promote new growth. 
Also, you need to trim them every two to three years, as the plant grows, it gets congested in an area.
Trimming or dividing plants will generate new growth opportunities for the plant. 
Gardeners, usually trim black mondo grass a few inches back during winter to get them ready for growth during the spring season.
Do not trim the plant during the spring and summer seasons because these are growing seasons for the plant, trimming in this period will lead to a lack of growth.

How fast does black mondo grass spread?

Black mondo grass is a slow-growing plant. It takes two to three months to get established. Also, when grown from seeds it takes around three months to sprout a seedling. So, the plant spread gradually. Roughly, the plant reaches about 1 foot wider within one or two years. But, dwarf black mondo grass takes around two to three years to grow about 3 to 4 inches in ideal conditions.

Common Pests and Diseases

Black mondo grass is susceptible to some pests and diseases. The plant gets problems when it gets crowded in a close area. It is important to leave at least 4 inches of distance between each plant for good air circulation.

This ornamental grass is usually attacked by slugs in humid conditions. You have to look occasionally to pick out slugs from the plant.

Black Mondo Grass Species

Liriope known as black mondo grass has two species: creeping liriope and big blue lilyturf.

This species also has a slow growth rate like black mondo grass but growth slightly taller than black mondo grass. The best time to plant, grow or transplant them is in the spring season when plants wake from dormant. In moist weather, the plants do not dry easily which gives more time to plant them.

Creeping liriope grows slightly thicker than big blue lilyturf, so if you live in the northern region creeping liriope is a better choice. This species features blade-shaped leaves which are more narrow than big blue lilyturf.

Both plants produce flowers stalk in the growing season but the big blue lilyturf’s flowers are more visible as they extend above from plant’s foliage.