Liriope muscari, commonly known as Big Blue Lilyturf, is a highly popular and durable evergreen perennial frequently used in landscape design. Gardeners value this plant for its dense, grass-like foliage and its ability to thrive in a wide range of conditions, making it an excellent choice for groundcover and edging. The most common concern for those planting it is whether it will aggressively take over garden beds. The answer is that Liriope muscari spreads in a slow, predictable manner, maintaining a manageable form in the landscape.
Understanding Liriope Muscari’s Growth Habit
The fundamental characteristic of Liriope muscari is its clumping growth habit, which means it expands its mass outward from a central point rather than sending out distant runners. This makes it ideal for defined areas like borders, walkways, and mass plantings where a distinct edge is desired. A single plant will gradually increase its diameter, but it remains a cohesive, dense unit.
This behavior stands in stark contrast to its close relative, Liriope spicata, or Creeping Lilyturf. While the two species look similar above ground, L. spicata is known as a “running” groundcover because it spreads rapidly and aggressively. L. spicata uses long, far-reaching underground stems, or rhizomes, to invade surrounding areas, often making it problematic for gardeners seeking neat boundaries.
The predictable, well-behaved nature of Liriope muscari is what makes it the preferred species for formal edging. Its growth is focused on thickening the existing stand, typically spreading only about 12 to 18 inches in width over a long period. This distinction in growth habit is what separates a manageable garden plant from one that requires continuous control.
Mechanisms of Slow Expansion
The slow expansion of Liriope muscari occurs primarily through the production of short, underground structures called stolons, which are a type of short-range rhizome. These stolons emerge close to the parent plant, giving rise to new offsets that simply add to the density and diameter of the original clump. This vegetative increase results in the formation of a tight, fibrous root mass that can become quite dense over several years.
Another element contributing to the spread are small, fleshy, peanut-shaped storage organs, or corms, found along the fibrous roots. These corms can also sprout new growth, which again contributes to the slow, steady thickening of the plant mass. The combination of short stolons and sprouting corms ensures the plant is highly effective at covering an area densely without running amok.
A secondary and less frequent mechanism of spread is through seed dispersal. Liriope muscari produces small, blue-black berries after its late-summer flowering period. When these berries fall or are consumed and subsequently dropped by birds and small mammals, the seeds can germinate in new locations. This results in entirely new, isolated clumps appearing some distance away from the main planting, which is different from the continuous expansion caused by the stolons.
Strategies for Containing and Dividing Growth
The most effective strategy for managing and containing the slow spread of Liriope muscari is periodic division. When the clumps become too dense or begin to encroach on adjacent areas, they should be dug up and separated. This process involves lifting the entire root ball and using a sharp spade or knife to cut the dense mass into smaller, manageable sections.
Division can be performed successfully almost any time, but it is best done in early spring before new growth begins or in the fall. Dividing the plant every three to five years refreshes the planting and is a simple way to maintain the desired size and shape of the border. The divided sections can then be replanted to extend the border or shared with other gardeners.
Since Liriope muscari does not send out long, aggressive runners, simple, shallow landscape edging is highly effective for containment. Unlike the deep barriers required for running groundcovers, a standard plastic or metal border can easily restrict the short stolons from crossing into unwanted areas. This makes maintaining clean lines in the landscape a straightforward task.