Mondo Grass (Ophiopogon japonicus or Ophiopogon planiscapus) is a popular, low-maintenance choice for gardeners seeking a lush, grass-like ground cover. This evergreen perennial is a member of the lily family, known for its ability to form dense, spreading colonies. It is a slow-growing plant that works well in shaded areas or as an attractive border planting. Its clumping habit makes it an excellent substitute for traditional turf, especially in areas where mowing is difficult or undesirable.
Site Selection and Soil Preparation
Mondo Grass thrives in environments that offer shade or partial shade, though common green varieties can tolerate full sun if provided with sufficient moisture. Avoid locations where the plant will be subjected to intense, harsh afternoon sun, which can scorch the foliage. The optimal soil condition is well-draining, which is a significant factor in preventing root rot, a common issue when the plant sits in standing water.
Before planting, the area should be thoroughly cleared of existing weeds, which would otherwise compete with the slow-growing Mondo Grass for resources. Integrating organic matter, such as compost, into the top six inches of soil is highly beneficial. This amendment helps to improve the structure of heavy clay soils by enhancing drainage, while simultaneously assisting sandy soils with moisture retention. The plant generally prefers a slightly acidic to neutral soil pH, ranging from 5.5 to 7.0.
Preparing the Planting Material
Mondo Grass is typically purchased as established clumps or plugs. The first step in successful planting involves preparing this material by dividing the clumps. Gently separate the larger clump into smaller sections, which will serve as the individual planting units.
The goal is to create smaller “plugs” that each contain a generous amount of roots and several leaves or shoots. A gentle pulling motion is usually sufficient to tease the roots apart, though a sharp knife can be used for densely packed clumps. Ensuring each newly separated section has a viable root structure is important for rapid establishment and growth.
Placing and Spacing the Grass
When planting, dig a hole that is slightly wider than the root ball of the plug, but only as deep as the root ball itself. This technique ensures the plant will not settle too deeply after watering. Once the hole is ready, place the prepared plug inside, making sure the crown—the point where the leaves meet the roots—sits level with the surrounding soil surface, or slightly above it.
Backfill the hole with the prepared soil, gently firming it around the roots to eliminate any air pockets. Proper spacing is a primary consideration that determines the eventual density and speed of coverage. For mass plantings, standard Mondo Grass plugs should be spaced between 6 to 12 inches apart, while dwarf varieties may be planted as close as 4 inches apart. Closer spacing will encourage the plants to spread and form a continuous ground cover much faster than wider spacing.
Initial Establishment Care
Immediately after planting, the newly placed plugs require a thorough and deep watering to settle the soil and eliminate any remaining air pockets around the roots. During the first four to six weeks, consistent moisture is a top priority for the actively establishing root system. The soil should be kept uniformly moist, but not saturated or soggy, to encourage root growth without causing rot.
After the initial period, the watering frequency can be reduced, as the plant becomes more self-sufficient. Applying a light layer of organic mulch, approximately two to three inches deep, immediately after planting helps to maintain consistent soil moisture and regulate temperature fluctuations. Although Mondo Grass is a light feeder, a balanced, slow-release starter fertilizer or an application of a root stimulator can be applied during planting to give the young roots an initial boost. This focus on consistent moisture and root support during the early weeks ensures the plants successfully transition to their new location.