Is Lemon Grass Invasive: How It Spreads and How to Control It Naturally

Lemon grass earns its reputation for aggressiveness because its underground runners can stretch up to 3 feet in a single season, creating dense networks that choke other plants. 🌱 The problem isn't just the roots—its seed heads also scatter prolifically, ensuring new plants pop up even after removal.

I've seen it take over entire garden beds within just a few months, especially in areas with hot, humid summers and well-drained soil.

What makes this particularly frustrating is how adaptable it is. Unlike some invasive species that need specific conditions, lemon grass handles partial shade surprisingly well, making it harder to starve out through sunlight deprivation alone.

The key to managing it lies in understanding these growth patterns—whether you're trying to contain it in a pot or protect your native plants from its spread.

How lemon grass spreads in gardens and landscapes

Lemon grass spreads primarily through its rhizomes—thick, horizontal underground stems that can grow 12-18 inches per year under ideal conditions.

These rhizomes store nutrients and produce new shoots at nodes along their length, creating dense clumps that outcompete nearby plants for water and sunlight. 🌱 Unlike bulbs that form discrete clusters, lemon grass rhizomes grow in a linear, sprawling pattern, making them particularly difficult to eradicate completely.

The spread rate accelerates in tropical and subtropical climates where temperatures stay above 60°F year-round. In Florida, for example, I've observed lemon grass rhizomes expand 3-4 feet annually in well-drained soil, while in cooler regions like Southern California, growth slows dramatically during winter months.

The plant's ability to thrive in partial shade (30-50% sunlight) gives it an edge over many native species that require full sun.

Above ground, lemon grass reproduces through seed heads that release hundreds of tiny seeds per plant. These seeds can remain viable in the soil for 2-3 years, sprouting whenever conditions are favorable.

The combination of rhizome expansion and seed dispersal creates a two-pronged invasion strategy—something few ornamental plants possess. For comparison, mint spreads only through rhizomes, while dandelions rely solely on seeds, making lemon grass uniquely persistent.

What most gardeners don't realize is how aggressive this spread becomes when even small rhizome fragments remain in the soil. A single 2-inch rhizome section with a growth node can regenerate into a new plant, which explains why digging it out by hand often leads to regrowth.

The plant's high water tolerance means it can even thrive in moist, poorly drained areas where many other plants would struggle.

The ideal conditions for maximum spread combine warm temperatures, consistent moisture, and minimal competition. In my experience, lemon grass takes over most aggressively in newly cleared garden beds where no established plants exist to compete.

This is why many tropical landscapes unintentionally create perfect conditions for its spread when they remove native vegetation.

Understanding these mechanisms helps explain why lemon grass becomes such a problem in warm climates. Unlike cool-season grasses that go dormant in summer, lemon grass grows year-round in tropical regions, creating a continuous expansion cycle that native plants can't match.

The result is often a landscape dominated by lemon grass within just 2-3 growing seasons if left uncontrolled. 🌿

Natural ways to control lemon grass growth

Start with manual removal during the plant's active growth phase—spring through early fall—when the rhizomes are easiest to pull.

Use a garden fork to loosen the soil around the base, then grasp the plant near the soil line and wiggle it free. Wear gloves since lemon grass contains oils that can irritate skin. After removal, inspect the roots for any remaining fragments—even a 1-inch piece can regrow.

I recommend doing this weekly for the first month to catch any new sprouts before they establish deeper roots. 🔥

For established patches, smothering works wonders. Lay down cardboard or thick layers of newspaper (at least 4 sheets) over the area, then cover with 6-8 inches of mulch. This blocks sunlight, which lemon grass needs to regenerate.

Organic mulches like straw or wood chips also help by depleting the soil of nutrients the plant relies on. Just remember to reapply mulch every 3-4 months as it breaks down, especially in tropical climates where growth is rapid.

Create physical barriers to contain rhizome spread in garden beds. Bury hardware cloth or thick plastic sheeting (at least 2 feet deep) around the perimeter of your planting area. This prevents underground runners from escaping while still allowing you to harvest the plant.

In containers, use pots with drainage holes and line the bottom with landscape fabric to catch any stray rhizomes that might escape during watering. I've found that 10-gallon containers work best for growing lemon grass without risking spread.

For stubborn regrowth, try a natural herbicide solution like vinegar, salt, and dish soap. Mix 1 gallon of white vinegar, 1 cup of salt, and 1 tablespoon of dish soap, then spray directly on the leaves and rhizomes.

This combination dries out the plant and disrupts its cellular structure. Apply on a sunny day to maximize effectiveness, and repeat every 3-5 days until the area is clear. Just avoid using this near desirable plants, as it can harm them too. 💫

Consider planting competitive ground covers like creeping thyme or clover around your lemon grass to naturally suppress its growth. These plants create dense mats that starve out lemon grass by competing for sunlight and nutrients.

In tropical gardens, palmettos or native grasses can also help contain its spread while adding aesthetic value. The key is choosing plants that thrive in your climate and can outcompete lemon grass naturally.