Monkey grass, often admired for its lush, evergreen foliage and neat clumping or spreading habits, is a staple in many landscape designs. Whether used as a border, groundcover, or accent plant, its low-maintenance nature is a significant draw for gardeners. However, even the most low-maintenance plants benefit from occasional care, and monkey grass is no exception. Trimming, while not a frequent requirement, plays a crucial role in rejuvenating old growth, maintaining a tidy appearance, and promoting healthy new foliage.

Knowing when and how to trim your monkey grass border can make the difference between a tired, ragged edge and a vibrant, well-defined landscape feature. This guide will delve into the different types of monkey grass, the tools you’ll need, and the simple steps to effectively trim your borders for optimal health and aesthetics.

Types of Monkey Grass

The term “monkey grass” is commonly used to refer to two distinct, yet similar, genera of evergreen, grass-like perennials: Liriope and Ophiopogon. While both are popular for similar landscape uses and share a similar common name, they have subtle differences that can influence their growth habit and how you might approach their maintenance.

Liriope (Liriope muscari and Liriope spicata)

Often called “Lilyturf,” Liriope is perhaps the most common plant referred to as monkey grass.

  • Liriope muscari (Clumping Liriope): This species grows in dense clumps and tends to stay where it’s planted, making it ideal for neat borders, edgings, or as an accent plant. It typically grows 10-18 inches tall and produces spikes of lavender or white flowers in late summer, followed by black berries. Popular cultivars include ‘Big Blue’, ‘Monroe White’, and ‘Variegata’ (which has variegated foliage). Its clumping habit makes it relatively easy to maintain a defined border.

  • Liriope spicata (Creeping Liriope): Also known as “Creeping Lilyturf” or “Creeping Monkey Grass,” this variety spreads aggressively by rhizomes, forming a dense groundcover. While excellent for erosion control or filling large areas, its spreading nature means it can become invasive in garden beds if not contained. It generally grows shorter than L. muscari, around 6-12 inches, with less prominent flowers. Due to its aggressive spread, it requires more vigilance to keep its borders in check.

Ophiopogon (Ophiopogon japonicus and Ophiopogon planiscapus)

Known as “Mondo Grass,” Ophiopogon species are typically smaller and have a finer texture than Liriope.

  • Ophiopogon japonicus (Dwarf Mondo Grass): This is the most common Mondo Grass, growing in very dense, low clumps, typically 4-6 inches tall. It has fine, dark green, almost wire-like foliage. It spreads slowly by rhizomes, forming a very tight groundcover or border. It produces inconspicuous white to pale lavender flowers that are often hidden by the foliage, followed by blue-black berries. Its slow, contained growth makes it ideal for precise, low borders and between stepping stones.

  • Ophiopogon planiscapus ‘Nigrescens’ (Black Mondo Grass): A striking cultivar of Mondo Grass, famous for its nearly black foliage. It grows similarly to O. japonicus but tends to be slightly taller (up to 8-12 inches) and spreads slowly. It produces pale pinkish-white flowers in summer, followed by black berries, which stand out against its dark leaves. Like other Mondo Grass varieties, it’s slow-growing and maintains a neat border easily.

Impact on Trimming: The primary difference relevant to trimming is their growth habit. Clumping Liriope muscari and all Ophiopogon varieties generally maintain their form better, requiring less frequent and less aggressive trimming. Creeping Liriope spicata, on the other hand, might require more frequent trimming or root pruning to keep its spreading nature in check and prevent it from encroaching on other plants.

Tools For Trimming Monkey Grass

The right tools make trimming monkey grass borders easier, more efficient, and result in a cleaner cut that promotes healthier regrowth.

  • Hedge Shears (Manual or Electric):

    • Manual Hedge Shears: Excellent for smaller borders, precise shaping, and when you want quiet operation. They provide good control but require more physical effort.
    • Electric/Battery-Powered Hedge Trimmers: Ideal for longer borders or larger areas. They make quick work of trimming but are less precise for fine details and might be overkill for very small patches. They are best for a uniform, straight cut.

  • Hand Pruners/Bypass Shears:

    • Useful for removing individual brown or damaged blades, or for making precise cuts around obstacles. Not practical for trimming entire borders.

  • String Trimmer (Weed Eater):

    • Can be used for a quick trim of a border, but it’s generally less precise than shears and can shred the foliage, leading to ragged edges. If using a string trimmer, ensure it has a sharp line and use a very steady hand. Best for quick rejuvenation cuts rather than precise shaping.

  • Leaf Rake/Hand Rake:

    • Essential for raking out old debris and clippings after trimming. A hand rake is particularly useful for getting into the dense clumps.

  • Garden Gloves:

    • Always wear sturdy garden gloves to protect your hands from sharp blades and potentially abrasive foliage.

  • Tarp or Drop Cloth (Optional but Recommended):

    • Lay this down alongside your border to catch clippings, making cleanup significantly easier.

Blade Sharpness: Regardless of the tool, ensure its blades are sharp. Dull blades tear and damage the grass, leaving ragged edges that turn brown and make the plant more susceptible to disease. Sharpen your shears or replace trimmer line regularly.

Trimming Monkey Grass

The timing and technique of trimming monkey grass are crucial for its health and appearance. The goal is typically to remove old, tired, or brown foliage to make way for fresh, green growth.

When to Trim Monkey Grass:

The best time to trim monkey grass is in late winter or very early spring, just before new growth begins to emerge.

  • Late Winter (February - March in most temperate climates): This timing is ideal because:

    • The grass is dormant or semi-dormant, minimizing stress to the plant.
    • The old foliage has already served its purpose through winter, protecting the crown.
    • You remove the old growth before the new, vibrant green blades begin to push through. If you wait until new growth is well underway, you risk cutting off new shoots, which can set the plant back and look unsightly.
    • This ensures the new season’s growth is fresh, uniform, and vigorous.

  • Avoid Summer Trimming: Do not trim monkey grass during the active growing season (late spring through fall). Cutting it back during hot weather can stress the plant, lead to browning, and make it more susceptible to disease. The new growth won’t have enough time to establish before intense heat or cold.

  • Exception for Appearance: If you have an isolated patch of heavily browned or damaged foliage in the summer (e.g., from severe drought or a specific localized issue), you can selectively snip out those individual dead blades with hand pruners, but avoid a widespread cut-back.

How to Trim Monkey Grass:

The process is straightforward, but consistency is key for a uniform look.

  1. Prepare the Area: Lay down a tarp or drop cloth along the border to catch clippings. This will save a significant amount of cleanup time.

  2. Determine Your Cut Height:

    • For most Liriope varieties, aim to cut back to about 2-4 inches above the ground. This removes the majority of the old foliage without damaging the crown.
    • For shorter Ophiopogon (Mondo Grass) varieties, cut back to about 1-2 inches above the ground. Since they are naturally shorter, a very low cut is fine.

  3. Use the Right Tool:

    • For long, straight borders: Electric or manual hedge shears are the most efficient. Hold the shears parallel to the ground or at a slight angle to create a consistent height. Take small, steady passes.
    • For curved borders or precision: Manual hedge shears or even sharp bypass pruners (for very small areas) will give you more control.
    • For rejuvenation (less precision): A string trimmer can be used, but be aware it might result in a rougher cut. Keep it moving to avoid shredding.

  4. Cut Uniformly:

    • Maintain a consistent height across the entire border. Step back periodically to assess your work and make adjustments.
    • Cut straight across the top. You don’t need to shape the sides much, as monkey grass naturally grows in a tidy form.

  5. Clean Up:

    • Once you’ve finished trimming, rake up all the clippings from the border and the surrounding area. Leaving old clippings can smother new growth and potentially encourage fungal issues.
    • Inspect the border for any missed spots or remaining brown blades and snip them out with hand pruners.

  6. Water and Fertilize (Optional but Recommended):

    • After trimming, a good watering will help new growth emerge.
    • You can apply a light, balanced fertilizer (e.g., a slow-release granular fertilizer) to encourage vigorous new growth. Follow product instructions carefully.

What About Trimming for Creeping Liriope (Liriope spicata)?

For Liriope spicata, in addition to the annual cut-back, you might need to address its spreading habit.

  • Edging: Install a physical border edge (plastic, metal, or brick) sunk at least 4-6 inches into the ground to contain its rhizomes.
  • Root Pruning: If it’s spreading beyond its bounds, use a sharp spade to cut through the rhizomes along the desired border edge. This can be done annually or as needed.
  • Dividing: Every few years, you may need to dig up and divide overgrown clumps of Liriope spicata to prevent it from taking over.

Trimming Monkey Grass: It’s Simple

While “simple” might seem understated for landscape maintenance, trimming monkey grass truly is one of the more straightforward tasks, primarily due to the plant’s resilience and low-fuss nature. The key takeaway is less about complex techniques and more about proper timing and sharp tools.

By consistently cutting back your monkey grass in late winter or early spring, you remove the faded, old foliage, which not only dramatically improves its aesthetic appeal but also provides the impetus for a flush of healthy, vibrant new growth. This annual rejuvenation ensures your monkey grass borders remain dense, lush, and a crisp, attractive feature in your landscape, serving their purpose beautifully year after year with minimal effort. It’s a simple step that yields significant rewards for the overall health and visual impact of your garden.