Cymbopogon nardus, commonly known as citronella grass, is a tropical, clump-forming plant recognized for its distinctive lemony fragrance. Valued for its ornamental appeal and essential oil, it can be propagated through division or seed.
Propagating by Division
Dividing an established Cymbopogon nardus clump offers a reliable method for creating new plants. The ideal time for this process is during the spring or early summer, when the plant is actively growing. Before beginning, prepare necessary tools such as a sturdy shovel or spade, a sharp knife, and gardening gloves. Watering the mother plant thoroughly the day before division helps to reduce transplant shock and makes the root ball easier to manage.
To divide, carefully dig around the clump, extracting as much of the root system as possible. Once lifted, shake off excess soil to expose roots and rhizomes. Use a sharp knife or spade to divide the clump into smaller sections, ensuring each has healthy roots and foliage. Trimming leaves back to about 6 inches helps new plants focus energy on root establishment.
Prepare the new planting sites with well-draining, loamy soil, ideally amended with compost or other organic matter to provide nutrients and improve structure. Replant the divisions immediately at the same depth they were previously growing, ensuring adequate spacing for future growth. After planting, water the newly divided plants thoroughly to settle the soil around the roots and encourage establishment.
Propagating by Seed
Propagating Cymbopogon nardus from seed is less reliable than division due to low germination rates. Seeds can be sown indoors 10 to 12 weeks before the last frost, or directly outdoors two weeks after the last frost once the soil has warmed.
Lightly scatter seeds on the surface of a well-draining seed-starting mix. Do not cover them deeply, as they require light to germinate; a gentle press ensures good seed-to-soil contact. Maintain a consistent soil temperature of 70-75°F (21-24°C) for optimal germination, using a heat mat to improve success.
Keep the soil consistently moist but never waterlogged by misting regularly to prevent the tiny seeds from being displaced. Seedlings typically emerge within one to three weeks under these conditions. Once seedlings develop at least three sets of true leaves or reach about 2 inches in height, they are ready for transplanting into larger individual pots or their final outdoor location. Handle the delicate seedlings by their leaves rather than their stems to minimize damage during this process.
Caring for New Cymbopogon Nardus Plants
Proper care helps new Cymbopogon nardus plants establish and thrive. Immediately after planting or transplanting, water thoroughly to help them settle. Maintain consistent soil moisture, especially for container plants, allowing the top inch of soil to dry slightly between waterings.
New plants require ample sunlight, ideally at least six hours of full sun to partial shade daily. In hot climates, afternoon shade can prevent leaf scorching. The plant prefers well-draining, loamy, slightly acidic soil (pH 5.8-7.0). Incorporating compost or other organic materials before planting provides essential nutrients.
While Cymbopogon nardus is not a heavy feeder, a diluted balanced fertilizer, such as a 5-5-5 or 10-10-10 formulation, can be applied monthly to potted plants or annually in spring for established garden plants. For plants in the ground, adding compost during planting might negate the need for additional fertilization. As a tropical plant, Cymbopogon nardus is sensitive to cold; in regions where temperatures drop below 32 degrees Fahrenheit (0 degrees Celsius), plants should be brought indoors or provided protection during winter.
Common Propagation Challenges
Several challenges can arise when propagating Cymbopogon nardus. A frequent issue with seeds is very low germination rates, making this method impractical for some. If seeds sprout, young seedlings can become leggy without sufficient light.
For plants propagated by division, a common problem is the failure of new sections to establish, often evidenced by wilting or a lack of new growth. This can stem from root damage during the division process, or from improper watering, such as dehydration or overwatering leading to rot. Overwatering can also manifest as brown spots on leaves, while drooping leaves might signal either insufficient water or inadequate light. Root rot is a significant concern if the soil remains waterlogged.
While generally resilient, young Cymbopogon nardus plants can face issues with common garden pests like aphids, spider mites, or whiteflies. Though not typically susceptible to many diseases, fungal infections can occur in environments with high humidity or poor air circulation.