How to Plant, Grow, and Care for Black Mondo Grass

Do you have a bit of a spooky streak? Love plants that look like they should grow outside that haunted house on the hill? Black mondo grass is the ideal low-maintenance, creepy ground cover. But it also looks amazing even outside of a goth’s garden!

Also known as Ophiopogon planiscapus ‘Nigrescens’, black mondo grass is a drought-tolerant plant that isn’t technically a grass. It’s part of the same plant family as asparagus, in fact. Hovering within eight inches of the ground, black mondo grass can form a darker contrast to a bright floral display.

For dramatic flair, black mondo grass can’t be beat. It’s not just a plant for Halloween anymore. This ghoulish garden-dweller can also be a glorious bedding plant. And it produces flowers, too!

So let’s explore this dark and mysterious black mondo grass in depth. We’ll eliminate its eerie image and show you how best to bring this stunner to light in your yard. All this so you can plant black mondo grass at home!

What is Black Mondo Grass?

In all seriousness, black mondo grass is nowhere near as dark and foreboding as I suggested earlier. Low-maintenance, it looks beautiful as a border edging or dappled through rock gardens. Known botanically as Ophiopogon planiscapus ‘Nigrescens’, it has common names, including black mondo grass, lilyturf, and monkey grass.

Native Area

The native origins of black mondo grass are in Japan, but it’s traveled around the globe. Because of its unique coloration, it’s become a dramatic contrast plant for landscaping. Called monkey grass in the southern US, this plant also produces flowers on a long, slender raceme in fall.

Characteristics

The long, slender, and strap-like leaves of black mondo grass can range from green to purplish-black. The warmer the weather, the darker their coloring becomes. That deep coloration can provide a dramatic counterpoint to brighter blossoms.

Not all forms of mondo plant are black! There are cultivars that are much lighter in color. While they also darken in the sun’s warmth, their edges can stay off-white. The centers of the leaves remain a dark green hue. Lighter plants are often called lilyturf, a name often used for Liriope species as well.

The black mondo grass perennial forms tight, matted clumps in its bed and grows in zones 5-11. It provides year-round color in those zones, but its active growing season occurs in spring and summer.

Varieties

Ophiopogon is a large genus. There are quite a few related plants to mondo grass. While we’re focusing on Ophiopogon planiscapus today, don’t rule out the black mondo grass cousins! I’ll mention two with similar growth habits and tendencies to mondo grass.

But let’s talk lilyturf first. There are a few popular cultivars to zero in on.

Ophiopogon planiscapus ‘Nigrescens’

This is the deepest and the darkest variety, the one which gave mondo grass its “black” name. Reported to have a sweet fragrance, it blooms with lavender to purple bell-shaped flowers. In time, these flowers produce an inedible berry that holds its seeds.

The long leaves of this black mondo grass begin as dark green but deepen in the heat to become so dark they turn charcoal-colored. Slightly reflective, they can have a greyish cast to them in certain lighting. These can survive in USDA zones 5-10 but do especially well in zones 7-9.

Ophiopogon planiscapus ‘Little Tabby’ or ‘Silver Ribbon’

A pair of popular cultivars, ‘Little Tabby’ and ‘Silver Ribbon’, are similar in color. These are more commonly called lilyturf or monkey grass than mondo grass. Their silvery-white edges fade into a vivid, dark green leaf.

The flowers are white but also morph into a deep purple-colored inedible berry as they fade. These are sometimes confused with Ophiopogon intermedius, which is called Aztec grass. But Aztec grass grows to 12-24″ in height, whereas these stay closer to the ground.

Other Related Species

Ophiopogon japonicus (mondo grass or fountain plant)

While it shares the common name of mondo grass, O. japonicus has wider leaves and larger flowers. Many dwarf cultivars of this have been developed. Popular varieties include ‘Albus’, ‘Kyoto Dwarf’, and ‘Silver Mist’.

Only reaching a height of two to three inches tall, it makes a beautiful miniature form and is often used in fairy gardens. This species tends to stay deep green in coloration, and its blooms are white to lavender.

Ophiopogon umbraticola or Ophiopogon chingii

Even more slender-leaved than its kin, O. umbraticola and the similar O. chingii grow four to six inches in height and produce white flowers. Originating in China, they tend to be less erect than planiscapus, looking a bit like a more unruly grass.

Also, unlike its relatives, O. umbraticola does not spread through rhizome-like roots. It stays put quite well. This plant works well for a pop of vivid green color. It will not spread to form a ground cover, so to use it that way, you will need to plant densely.

Ophiopogon intermedius (Aztec grass)

Aztec grass tends to be a larger plant, suitable as a decorative bedding plant. Its leaves are striped pale green and white, and it doesn’t reach the darker colors that its cousins do. Heights of 18-24″ are not uncommon in larger specimens.

I like this white-flowering plant as a border plant. It’s quite popular in the south to southeastern US. Alas, it doesn’t hold up to the winter cold in the northern portions of the country. It prefers USDA zones 7-10 for the best growth.

Be forewarned: Aztec grass spreads rampantly and can become invasive if it likes your climate.

Planting

To plant black mondo grass start by selecting a spot with partial shade to full sun, depending on your climate. Prepare well-draining soil enriched with compost or organic matter to improve fertility and drainage.

Dig holes about four to six inches apart. They are slow-growing plants that eventually spread to form a dense ground cover. Place each division or potted plant into the hole at the same depth as it was previously growing, then backfill with soil and gently press to eliminate air pockets.

Water thoroughly after planting and keep the soil evenly moist, especially during the establishment phase. Adding a layer of mulch helps retain moisture and suppress weeds. Once established, black mondo grass is low-maintenance, requiring minimal watering and care.

How to Grow

But how does one practice proper black mondo grass care? How drought-tolerant is it, really, and what’s the best soil blend? Let’s talk about that!

Light

Full sun to partial shade is what’s recommended for black mondo grass, but it should be a “cool full sun”. If you’re in a hot, desert-like climate, afternoon shade is preferable. Too much full sun or direct sunlight in extreme heat can damage the tender leaves.

Water

While Ophiopogons have relatively mild water requirements, they still need moisture. Maintaining consistently damp soil will help keep them healthy and improve flowering capability. However, they do not like overly wet conditions.

Water black mondo grass a bit more regularly during the first year after planting. After it’s established, it can tolerate the occasional dry period, but it still prefers even moisture levels.

A mulch can help maintain the moisture of the soil around black mondo grass. Those in direct sunlight will thank you. Opt for something which sets off the look of the grass-like leaves well, like a contrasting wood chip.

Black mondo grass is tolerant of humidity as long as there’s good airflow around its location. If it’s boxed in and the air is hot and sticky, it may wilt a bit.

Soil

Humus-rich, slightly acidic, well-draining soil is best for black mondo grass. For best growth, aim for a pH range between 5.5 and 6.5. Avoid clay-like soils when possible, as these are too hard for the roots to penetrate easily.

Excess water needs to drain away to prevent root damage. Avoid muddy conditions, especially in hot climates!

Temperature

Black mondo grass is considered cold-hardy, but that should actually mean frost-tolerant. If you get hard freezes, your plant will suffer. The rare light frost shouldn’t do more than cosmetic damage.

Fertilizer

Fertilizing black mondo grass with a balanced fertilizer should be rare. A spring application of compost around the plant’s base should be more than enough to feed it and support the plant’s health.

Maintenance

Some sources have suggested mowing your black mondo grass. Please don’t do that. It can take months to years to recover. This plant seldom, if ever, needs pruning. Instead, remove dead or disfigured leaves as necessary. Pruning is wholly cosmetic.

Propagation

While black mondo grass will spread, its spread is very slow. It’s much easier to divide off new plants in the spring.

Remove a large clump of black mondo grass from the soil, being careful to not harm its fibrous root system. Dust off excess soil. Using your hands, separate off smaller clumps, each with its own roots and leaves.

Once separated, you can plant black mondo grass at four inch intervals to provide a good cover. Carry out mass planting of large quantities of plugs and you’ll have an entire garden of the stuff.

You can grow black mondo grass from seed contained within its purple berries, but it is time-intensive. Black mondo seed has a low germination rate. It’s also slow to germinate and can take anywhere from 30-150 days. Since it’s a slow-growing plant, preparing enough starts for a ground cover takes a while!

Common Problems

As long as it’s given the right conditions, your black mondo grass plants will thrive. But what if they’re not performing right? Now that we’ve talked about black mondo grass care let’s troubleshoot.

Growing Problems

Underwatering can cause black mondo grass plant wilting. Plants in direct sunlight are more susceptible. If the soil is dry more than an inch below the surface, it’s time to water. Consider adding mulch to slow the evaporation of soil moisture, especially in zones with extreme heat.

Avoid excessive pruning, as the plant grows quite slowly. Too much pruning will make it look less appealing.

Pests

Most pests seem to ignore black mondo grass! But there are two that don’t, both related: snails and slugs. These can chew holes in leaves or gnaw the leaves right off your gorgeous black mondo grass. Use organic bait to lure them away from plants and kill them off.

Diseases

The biggest problem you’re likely to face – especially in mass planting areas – is pythium root rot. This fungal rot can develop when the soil is too moist, causing yellowing and browning of the plant’s leaves. If not treated, it can lead to black mondo grass plant death. Treatment of root rot should begin by reducing your watering regimen.