Cymbopogon nardus, commonly known as Citronella Grass, is a clump-forming perennial grass. It features long, thin, bright green leaves that release a distinct lemony fragrance when brushed or crushed. This tall, upright grass adds a unique textural element and its refreshing scent makes it a favored choice for many gardeners.
Essential Growing Conditions
Citronella Grass thrives in locations that receive at least six hours of direct sunlight daily. This supports vigorous growth and optimizes aromatic oil production. While it can tolerate some afternoon shade in extremely hot climates, insufficient light may lead to leggy growth and a less potent fragrance.
The plant requires well-draining soil to prevent root rot. An ideal soil pH for Cymbopogon nardus ranges from slightly acidic to neutral. For heavy clay soils, incorporating organic matter like compost, sand, or perlite improves drainage and aeration. While it tolerates poorer soil, the grass flourishes in rich, fertile environments.
Cymbopogon nardus needs consistent moisture but should never be waterlogged. Water regularly, especially during dry periods, to keep the soil evenly moist. Check the top inch or two of soil for dryness before watering again to prevent both over and under-watering. Adjust watering frequency based on local climate and whether the plant is in the ground or a container.
Originating from tropical regions, Citronella Grass prefers warm temperatures, growing best between 60°F and 90°F (15°C and 32°C). It is winter hardy in USDA zones 10 through 12, where it grows as a perennial. In colder climates, where temperatures drop below freezing, it is typically cultivated as an annual or brought indoors for winter.
Planting and Potting
Selecting the right location is important for successful growth. When planting directly into the ground, choose a sunny spot with sufficient space to accommodate its mature size, which can reach up to 8 feet tall and 5 feet wide. Ensuring good air circulation around the plant promotes overall health.
When planting Cymbopogon nardus from seeds, sow them after the last frost, once soil temperatures have warmed. For transplanting starts, dig a hole twice as wide as the root ball and just as deep. Gently place the plant in the hole, backfill with soil, and lightly firm around the base to remove air pockets. If planting multiple plants, allow 24-36 inches (60-90 cm) between each one for adequate spread.
For container growing, select a pot with ample drainage holes to prevent water accumulation. A container at least 12-18 inches in diameter suits a single plant, allowing space for root development. Use a high-quality potting mix formulated for good drainage, often containing perlite or sand. After planting, water thoroughly to settle the soil around the roots.
Ongoing Care and Pruning
Regular pruning encourages bushier growth and maintains the desired shape and size of your Citronella Grass. Removing yellowing or dead leaves improves the plant’s appearance and channels energy into new growth. Prune throughout the growing season using clean, sharp shears, cutting foliage back close to the base. A significant cutback in late summer can rejuvenate the plant.
Citronella Grass is not a heavy feeder and requires minimal fertilization. If the plant shows signs of nutrient deficiency, such as stunted growth or pale foliage, apply a light balanced liquid fertilizer. Apply once a year in spring, at half the recommended strength, to support healthy development. Over-fertilization can lead to excessive leafy growth at the expense of fragrance.
Cymbopogon nardus is naturally resistant to most common garden pests and diseases, making it a low-maintenance plant. Its strong aroma often deters insects, so significant pest infestations are rare. Maintaining proper watering and good air circulation are the best preventative measures. Should a minor problem arise, addressing it quickly with organic solutions, like insecticidal soap, is effective.
Overwintering Strategies
For gardeners in colder climates outside USDA zones 10-12, Cymbopogon nardus can be overwintered indoors. Before the first hard frost, inspect potted plants for pests, then bring them inside to a location with bright, indirect light. Reduce watering significantly during dormant winter months, allowing the soil to dry out more between applications.
Another overwintering option is to take cuttings from mature plants before cold weather. Select healthy stems, cut them into sections, and root them in water or a moist potting mix. These cuttings can be grown indoors over winter, providing new plants for the following spring. This method effectively propagates the plant and ensures its return.
Gardeners in regions with harsh winters often treat Cymbopogon nardus as an annual, allowing it to die back with the first killing frost. The plant will not survive freezing temperatures outdoors in these zones. In such cases, new plants are purchased or propagated from cuttings each spring after frost danger has passed, ensuring a fresh display for the growing season.