The leaves of mondo grass are narrower than those of liriope.
The berries of mondo grass are bright blue, while liriope berries are black.
The flower stalks of liriope are usually quite showy and stick out above the foliage. You will not usually see the flower stalks of mondo grass, as they are typically shorter and hidden beneath the foliage. Even in the winter once the flowers and berries are all gone, you will notice more old stalks on the liriope, and will not usually see any in the mondo grass.
Mondo grass plants are typically shorter than liriope and may be darker green.
Mondo grass leaves are less likely to have winter discoloration or signs of insect or disease damage than liriope.
Liriope include grass-like flowering perennial plants native to East and Southeast Asia. Two of the species, L. muscari (lilyturf) and L. spicata (known as creeping liriope or monkey grass). It can be planted almost any time, from spring to fall, generally from nursery plants or divisions. It will grow and spread quite rapidly and likely will produce flowers in its first year.
Mondo grass is ideal in that it requires little maintenance. For this reason, it is an ideal plant to grow in areas that are difficult to reach such as along steep slopes, flower beds and under trees. It is a very resilient type of plant that is both tough and durable. It will stand up to everything from shade to deer – all it needs is to survive is moisture. The Garden has both Dwarf and Black Mondo Grass.
Because Mondo grass is less susceptible to winter discoloration and damage due to insects and diseases, it does not usually need to be cut back in the late winter/early spring. Liriope, however, grows very quickly and does best when cut back once every year. This also gives you a chance to remove fungal spores and scale insects that may be overwintering on the old foliage. Make sure to cut the foliage back before the new foliage begins to emerge, February is usually a good time of year. Make sure to use a clean, sharp blade set no lower than 3″. Remove all of the cut foliage to prevent spread of insect pests or diseases.
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