Citronella Lemon Grass – The Expert Guide To Growing Lush
Citronella lemon grass (Cymbopogon nardus or Cymbopogon winterianus) is a perennial clumping grass famous for its citrus-scented essential oils that naturally deter mosquitoes. To grow it successfully, provide full sun, well-draining soil with a neutral pH, and consistent moisture during the heat of summer.
While it thrives year-round in USDA zones 9-12, gardeners in cooler climates can easily grow it as an annual or in large containers to bring indoors during winter. Regular nitrogen-rich fertilization and annual division will keep your plants vibrant and effective.
Do you dream of enjoying your backyard patio without the constant buzz and sting of mosquitoes? Many homeowners search for natural solutions that look beautiful and smell even better than chemical sprays.
Growing citronella lemon grass is one of the most rewarding ways to create a functional, aromatic barrier in your landscape. This versatile plant offers a striking architectural element to your garden while providing the source of the world’s most famous natural insect repellent.
In this guide, I will walk you through everything from soil preparation and NPK ratios to winter survival strategies. Whether you are a weekend DIY gardener or a professional landscaper, you will learn how to master this fragrant perennial.
Understanding the Citronella Lemon Grass Identity
Before you head to the local nursery, we must clear up a common botanical mix-up. Many stores sell a “Mosquito Plant” which is actually a scented geranium (Pelargonium graveolens).
While those geraniums smell like citrus, they do not contain the high concentrations of essential oils found in the true grass. True citronella lemon grass belongs to the Cymbopogon genus, the same family as culinary lemongrass.
The variety known as Cymbopogon nardus is the heavy hitter for oil production. It features long, slender green blades that can reach heights of five to six feet in a single season, making it an excellent choice for privacy screening.
Cymbopogon Nardus vs. Cymbopogon Citratus
You might wonder if you can cook with your citronella grass. While it is related to culinary lemongrass (Cymbopogon citratus), it is generally not used for eating.
The citronella variety has a much stronger, almost medicinal citrus scent. Its base stems are often reddish or purplish, whereas culinary lemongrass stays pale green or white at the bottom.
If your goal is pest control and landscaping, stick with the nardus or winterianus species. They produce more biomass and more potent oils for your outdoor living spaces.
Planting Citronella Lemon Grass for Success
Timing is everything when introducing this tropical beauty to your garden. Because it is a heat-loving species, you should wait until all danger of frost has passed and soil temperatures reach at least 65°F (18°C).
Choose a location that receives at least six to eight hours of direct sunlight daily. While it can survive in partial shade, the plant will become “leggy” and produce less of the essential oils you desire.
If you are planting in the ground, space your clumps about 24 to 36 inches apart. These plants expand quickly, and providing enough airflow between them prevents fungal issues in humid climates.
Potting for Portability
If you live north of USDA Zone 9, I highly recommend planting in containers. Use a large pot—at least 12 inches in diameter—with multiple drainage holes at the bottom.
A high-quality potting mix enriched with perlite or vermiculite ensures the roots stay oxygenated. Potted plants dry out faster, so keep a close eye on moisture levels during July and August.
Container growing also allows you to move the plants onto your deck or near your grill. This places the repellent foliage exactly where you need it most during evening gatherings.
Soil Health and Nutritional Requirements
Expert gardeners know that the secret to a lush “green screen” lies beneath the surface. This grass is a heavy feeder because it produces so much foliage in a short amount of time.
Start by testing your soil pH; these plants prefer a range between 6.0 and 7.0. If your soil is too alkaline, you can add elemental sulfur or peat moss to bring the levels down.
Incorporate several inches of aged compost or well-rotted manure into the planting hole. This improves soil structure and provides a slow-release source of micronutrients.
The Ideal NPK Ratio
To keep the blades vibrant and the oil production high, use a fertilizer with a balanced or slightly high-nitrogen NPK ratio. A 10-10-10 or 20-10-10 formula works exceptionally well.
Apply a granular fertilizer once every six weeks during the growing season. Always water the soil thoroughly after fertilizing to help the nutrients reach the root zone and prevent “root burn.”
For an organic approach, use fish emulsion or liquid seaweed every two weeks. These provide a quick boost of nitrogen that results in deep green, healthy foliage.
Essential Maintenance and Pruning Techniques
Maintaining citronella lemon grass is relatively straightforward, but it does require some “tough love” to look its best. Without pruning, the center of the clump can become choked with dead brown blades.
In early spring, or whenever you notice significant dead growth, use a pair of sharp bypass pruners to thin out the clump. You can even cut the entire plant back to about 6 inches above the ground to rejuvenate it.
This “hard prune” encourages a flush of fresh, tender growth. It also makes the plant more manageable if it has outgrown its designated space in your flower bed.
Division and Propagation
After two or three years, you may notice the center of your grass clump dying out. This is a signal that the plant needs to be divided.
Dig up the entire root ball using a sharp spade. Use a garden knife or the edge of your shovel to slice the clump into three or four smaller sections, ensuring each has a healthy set of roots.
Replant these “divisions” immediately. This is the most cost-effective way to expand your mosquito-repelling border without buying new plants every year.
Landscaping Design With Aromatic Grasses
When you integrate citronella lemon grass into your landscape, think about layers and textures. Its fountain-like shape provides a beautiful contrast to broad-leafed perennials like Hostas or Cannas.
I often suggest using it as a “thriller” in the center of large ornamental planters. Surround the base with “spillers” like sweet potato vine or “fillers” like lantana for a professional look.
In the ground, use it as a mid-height backdrop for shorter flowering annuals. The constant movement of the grass in the wind adds a dynamic, sensory element to your garden design.
Creating a “No-Fly Zone”
To maximize the repellent effect, plant the grass in areas where the wind will carry the scent toward your seating area. Placing them near entryways or windows can also help deter pests from entering the home.
Remember that the plant releases more scent when the leaves are brushed or crushed. Planting them along a walkway where people naturally rub against the blades is a clever design trick.
Just be mindful of the leaf edges. They can be quite sharp, so avoid placing them directly against narrow paths where bare skin might frequently come into contact with the foliage.
Troubleshooting Common Pests and Diseases
Fortunately, the very oils that repel mosquitoes also make this plant quite resistant to most garden pests. However, no plant is entirely “bulletproof.”
The most common issue is rust, a fungal disease that appears as small orange or brown spots on the leaves. This usually happens during periods of high humidity and poor airflow.
To treat rust, remove the affected blades and dispose of them in the trash—not the compost pile. Increase the spacing between plants and avoid overhead watering, which keeps the foliage wet for too long.
Dealing With Root Rot
If the tips of the grass start turning yellow and the base feels mushy, you are likely overwatering. Cymbopogon species hate “wet feet.”
Ensure your soil has adequate drainage. If you have heavy clay, consider planting in raised beds or amending the area with expanded shale or coarse sand.
Check the soil moisture by sticking your finger two inches deep. If it feels damp, wait another day or two before bringing out the hose. It is better to underwater slightly than to drown the root system.
Safety and Handling Guidelines
As a professional landscaper, I always emphasize safety when handling ornamental grasses. The leaves of citronella lemon grass contain microscopic silica edges that act like tiny saws.
Always wear heavy-duty gardening gloves and long sleeves when pruning or dividing. These “papercuts” can be irritating and may even cause a mild skin rash in sensitive individuals.
Keep your pruning tools clean. Wipe your blades with rubbing alcohol after use to prevent the spread of any potential pathogens between different plants in your garden.
Pet and Child Safety
While the plant is generally considered non-toxic in small amounts, the essential oils can be irritating if ingested in large quantities. It is best to keep curious pets and toddlers from chewing on the blades.
Furthermore, the sharp edges of the leaves can cause physical injury to a dog’s mouth or a child’s hands. Position the plants toward the back of the border to create a safe buffer zone.
If you plan to extract the oil for DIY sprays, always perform a patch test on your skin first. Pure citronella oil is very concentrated and can cause photosensitivity or irritation if not diluted properly.
Seasonal Transitions and Overwintering
As autumn approaches, you need a plan for your tropical grasses. If you live in Zone 8 or lower, a hard freeze will kill the plant down to the roots—and often kill the roots entirely.
For plants in the ground, you can try “banking” the crown. Cut the grass down to 4 inches and cover it with a thick 6-inch layer of pine straw or wood mulch to insulate the roots.
In many cases, however, it is easier to treat them as annuals or bring them indoors. If bringing them inside, do so before the first frost to avoid shocking the plant.
Indoor Care During Winter
Place your potted grass in the sunniest window you have, preferably south-facing. Growth will slow down significantly, which is normal during the dormant period.
Reduce your watering schedule and stop fertilizing entirely until spring. You want the plant to “rest” rather than push out weak, spindly growth in the low light of winter.
Watch out for spider mites, which thrive in dry indoor air. A quick misting or a occasional trip to the shower for a rinse will keep the foliage clean and pest-free until it can go back outside.
Frequently Asked Questions
Does Citronella Lemon Grass Actually Keep Mosquitoes Away?
Yes, but with a caveat. The living plant provides a mild repellent effect in the immediate area. For maximum protection, you need to crush the leaves to release the concentrated essential oils.
How Tall Does the Plant Get?
In ideal conditions with plenty of sun and nitrogen, it can easily reach 5 to 6 feet in height and 3 to 4 feet in width. It is a fast grower that can fill a large space in a single season.
Can I Grow It From Seeds?
You can, but germination is often spotty and slow. Most gardeners find it much easier to buy “starts” or nursery containers, or to propagate through division of an existing clump.
Is It Invasive?
In the United States, it is not typically considered invasive because it is a tropical plant that dies back in most climates. However, in frost-free tropical regions, it can spread via underground rhizomes if not managed.
Conclusion: Your Path to a Fragrant, Pest-Free Garden
Adding citronella lemon grass to your garden is more than just a landscaping choice; it is an investment in your outdoor comfort. By providing the right NPK balance, plenty of sun, and proper pruning, you can enjoy a lush, tropical oasis all summer long.
Remember to handle the sharp blades with care and give the roots plenty of room to breathe. Whether you use it as a privacy screen or a container centerpiece, this plant will reward you with beauty and a refreshing citrus scent.
Now is the perfect time to head to your local nursery and pick up a few starts. Transform your patio into a “no-fly zone” and take back your backyard today!
Taylor pairs an engineer's eye with years of hands-on work in soil, lawns and outdoor machinery. He tests ideas in his own garden, keeps tractors and mowers running himself, and speaks to local horticulture groups. Every Garden Aider guide is written to be practical, accurate and safe to follow.
“To bring life alive, you just need to mix some love with the compost, bedding, and gardening machines.”