How to Plant and Grow Mondo Grass

An easy-to-grow, attractive perennial groundcover, mondo grass is a good turf alternative in shade gardens. Hardy in Zones 6-10, its grass-like foliage forms dense tufts that slowly spread over time and require no mowing. In summer, small stalks of flowers appear on top of the crisp foliage. Mondo grass can also make a minimalist statement as a container plant indoors or out.

Where to Plant Mondo Grass

In many instances, shade gardens can be tricky to plant, especially when it comes to turf grass. With something as low maintenance as a mondo grass lawn, you can have the look of grass in shady spots. Mondo grass has no problem growing under large tree canopies, even between gnarled roots and rocks. However, if you're planting black foliage varieties of mondo, they'll need some sun, or the plants will be mostly green in full shade.

In the densest shade, you might not see many blooms. Typically, mondo grass blooms in the summer; its short spikes of pale pink or white appear just above (or sometimes in) the foliage of the plants. After the blooms fade, you may also see glossy dark purple to almost black berries.

How and When to Plant Mondo Grass

Plant mondo grass in early spring to give the roots time to take hold before the weather gets warm. Place it in an area with filtered sunlight to keep the plants from drying. Amend the soil to improve drainage and add the nutrients mondo grass needs. Weed the area and mix in compost to the top 6 inches of soil.

Divide mondo grass into small clumps with eight to ten leaves and many roots. Plant 4 to 12 inches apart. Water the top of the soil until it's moist to around 3 inches deep.

Mondo Grass Care Tips

Despite what the name might imply, mondo grass isn't an actual grass. It's in the lily family, as the dainty flowers suggest. The plants are very slow-growing and spread by stolons, which are horizontal stems just below the soil surface.

Light

When it comes to light exposure, mondo grass is not picky. The most common green varieties can take anything from full sun to shade. Leaf coloring may vary slightly depending on the exposure, including light green to deep emerald. Full sun is essential for the deep black-leaved varieties. The more shade, the more green the black becomes.

Soil and Water

One of the main drawbacks of mondo grass varieties is that they aren't drought tolerant. After they are established, colonies can take some drying out, but ideally, they need consistent moisture without being in standing water. Newly planted mondo grass should be planted in well-drained soil and watered a few times a week so the plants can establish roots. Mature mondo grass plants should be watered once a week.

Temperature and Humidity

Mondo grass is winter hardy in Zone 6 and higher. It will grow back after a freeze. It thrives in humid climates, so if your area is dry, mist it with water to give it moisture.

The foliage of mondo grass is evergreen in warm climates. In cooler temperatures, the leaves may die back, but they can be sheared in early spring before new growth begins.

Fertilizer

Fertilizer isn't necessary, but if you like, apply it every three months during spring and summer. Use a balanced 10-10-10 formula, following the manufacturer's instructions. Fertilizer will help maintain the grass's color.

Pruning

In early spring, cut back dead growth to make way for new grass. If needed, add mulch at that time.

Potting and Repotting Mondo Grass

Mondo grass is an excellent container plant because of its small size and slow growth rate. It is ideally suited for miniature garden projects and pairs well with many other plants.

Plant it in a small container filled with potting soil and keep it at room temperature. It is easy to pot (or repot) because it has such a shallow root system, so don't use a deep pot—a shallow one with drain holes is a better choice. Many varieties grow no wider than 6 inches, but some are more than twice that size. The small ones are better for indoor living. Learn the mondo grass's expected size before choosing a container; it should match the plant's anticipated width.

Water the plant regularly but lightly, and apply a slow-release balanced fertilizer in spring and midsummer. Mondo grass is such a slow grower that there may never be a need to repot it. If you do repot, give it new potting soil at that time.

Pests and Problems

Pythium root rot causes mondo grass's leaves to take on a burnt look, resulting in yellowing leaves and rotting roots. It's caused by heavy soil with poor drainage. It can be treated with appropriate products.

Pests that can damage mondo grass include snails and slugs, which eat through the top of the mounds and destroy the grass. Pick the pests off the grass and drown them in soapy water. Spray with iron phosphate to keep them away. If you live in a southern state, check that mondo grass hasn't been identified as invasive in your state, as it has in others, before you plant.

How to Propagate Mondo Grass

Mondo grass can be propagated via divisions or seed. Divisions is the simpler method for anyone who has (or can buy) a plant. Sowing seeds is a more unreliable method.

Mondo grass has tuberous rhizomes in which it stores water and nutrients. They make it easy to divide plants and establish new plantings. In early spring, dig up an established clump of mondo grass and divide it into small sections using your hands or a sharp knife. Each section should have about 10 leaves and a generous amount of roots. Then, replant the clumps where you want them to grow in the garden, spacing them 6 to 15 inches apart, depending on the projected size of the grown plant—whether dwarf or standard. Water the planted divisions and continue to water them for a few weeks until they are established.

Harvesting seed from an existing plant can be disappointing because hybrid cultivars don't reproduce accurately by seed. It is better to order seed from a garden center. Even in the best case, mondo grass seed has a poor germination rate, and the older the seed is, the worse the rate grows. Sow the seed soon after receiving it in pots filled with sterile potting soil and put them in a cold frame or another cool area. Cool weather results in the best germination rate. Keep the seeds moist at all times and expect germination in two weeks to six months. They won't all germinate at the same time.

Types of Mondo Grass

Dwarf Mondo Grass

Ophiopogon japonicus grows to 1 foot tall with linear green leaves. Spikes of pale whitish-lilac flowers nestle among the foliage. This tough plant makes a fine edging. Zones 7-10

'Nigrescens' Mondo Grass

Ophiopogon planiscapus 'Nigrescens' has tufts of strappy dark purple leaves about 6 inches tall. Spikes of lilac-pink flowers resembling grape hyacinth rise on stiff stems in summer. Zones 6-11

Mondo Grass Companion Plants

Loosestrife

These vigorous growers are beautiful additions to the garden. They vary from tall, stately plants suitable for borders to others that can be planted as creeping groundcovers. Flowers range from tight spikes of 1/2-inch to 1-inch cups carried alone or in whorls. Unfortunately, several sorts may become invasive and need to be corralled. Zones 4–9

Japanese Painted Fern

Japanese painted ferns are washed with silver and burgundy markings. Lady fern is equally grand, though not quite as showy. Either will add interest and texture to your shady spots. Unlike most ferns, these will tolerate dry soil. And they'll accept some sun if they have ample water. Zones 4–9

Ferns add delicate, feathery texture and tons of green to any garden bed. Like mondo grass, they prefer shady spots. Different types of ferns can vary from small, 8-inch plants to towering 6-foot-tall ones.

Astilbe

Astilbe brings a graceful, feathery note to moist, shady landscapes. In cooler climates in the northern third or so of the country, it can tolerate full sun, provided it has a constant moisture supply. In drier sites, however, the leaves will scorch in full sun. It will spread slowly over time where well-situated. Zones 4–8

Impatiens

Impatiens flowers constantly, adding color without much maintenance to a garden. It works well with mondo grass to add lightness to mondo grass's monochromatic coloring. Zones 10-11

Snow-in-Summer

These bright white flowers of snow-in-summer look striking when paired with black mondo grass, and since they're groundcovers, create a lively rug-like look. Zones 3-10

Garden Plan for Mondo Grass

Bold Woodland Garden Plan

Add a bright dose of color to a spot under a canopy of tree leaves.