Mondo grass, scientifically known as Ophiopogon japonicus, is an ornamental plant. This evergreen perennial forms dense tufts of slender, arching, grass-like leaves, making it a versatile choice for groundcover, borders, and accent plantings. Though often called “monkey grass,” it is not a true grass but a member of the lily family.
Mondo Grass Growth Characteristics
Mondo grass generally exhibits a slow to moderate growth rate, especially during its initial establishment. It expands through underground stolons and tuberous roots, forming dense clumps that gradually spread. Standard varieties of Ophiopogon japonicus can spread up to one foot wide within one to two years under optimal conditions. Dwarf varieties, like ‘Nana’, spread even more slowly, typically expanding about six inches in two to three years. This slow, clumping habit means patience is often required for the plant to fully fill an area, differentiating it from more rapidly spreading groundcovers.
Key Factors Affecting Growth
Light Exposure
Light exposure impacts mondo grass growth and appearance. While it thrives in partial to full shade, it tolerates full sun with adequate moisture. Full sun may result in lighter green foliage and can cause leaf tips to burn, especially in hot climates. Black-leaved varieties, such as Ophiopogon planiscapus ‘Nigrescens’, need some sun to develop their characteristic dark coloration; in deep shade, their foliage may appear greener.
Soil Conditions
Soil conditions are important for mondo grass growth. The plant requires well-draining soil and performs best in a slightly acidic environment (pH 5.0-6.5). Poor drainage, like compacted or waterlogged soil, can impede growth and lead to root rot. Incorporating organic matter, such as compost, improves drainage and nutrient availability, promoting healthier growth.
Consistent Moisture
Consistent moisture is important for mondo grass, especially for newly planted specimens establishing root systems. Young plants need regular watering, several times a week, to maintain moist soil. Mature plants benefit from weekly watering, though they are not considered drought-tolerant. Both prolonged drought and excessive overwatering can hinder growth.
Temperature and Climate
Temperature and climate influence the plant’s growth. Mondo grass is hardy in USDA Zones 6 through 10, with new growth beginning in early spring in cooler regions. It prefers warm, but not excessively hot, temperatures, with an ideal range between 41 and 95 degrees Fahrenheit (5 to 35 degrees Celsius).
Nutrient Availability
Nutrient availability and fertilization practices influence the plant’s health and growth rate. Mondo grass is not a heavy feeder, but it benefits from periodic nutrient replenishment. Fertilization can enhance the plant’s color and encourage growth.
Optimizing and Managing Growth
To encourage robust growth and faster coverage, proper planting techniques are key. Planting in early spring allows ample time for root establishment. Spacing plants closer together (4 to 12 inches for standard varieties, 2 to 4 inches for dwarf types) helps an area fill in more quickly. Ensuring well-draining soil enriched with compost at planting provides an ideal foundation for development.
Consistent watering, especially during the first growing season, supports root development. Supplemental irrigation during dry periods prevents wilting and maintains steady growth. An annual application of a balanced, slow-release fertilizer in early spring can promote healthy foliage.
Mondo grass spreads slowly, so aggressive containment is rarely needed. If managing its spread is desired, division of established clumps every two to three years in early spring can control size and provide new plants. This division process involves gently separating the tuberous roots and stolons, ensuring each new section has several leaves and a good root system. Routine maintenance, such as trimming ragged or discolored leaves in late winter or early spring, maintains appearance and encourages fresh growth.