Lemongrass (Cymbopogon citratus) is a tropical clumping grass prized for its intense citrus aroma in Southeast Asian cuisine. The pale, firm base of the stalk is the most desirable part for cooking, requiring thick, bulbous growth to be useful. Cultivating this robust, flavor-packed growth requires intensive care beyond simple gardening practices. The goal is to provide the exact conditions and cultural practices that trigger the plant to produce numerous, wide, and easily harvestable stalks.
Starting Lemongrass: Propagation Methods
The fastest and most common method for establishing a lemongrass plant is through propagation of fresh stalk cuttings, often obtained from a grocery store. When selecting a stalk, look for one with a firm, intact base that shows no signs of drying or rot. Initiate growth by placing the bottom few inches of the stalk into a glass of water, ensuring the base is submerged.
Position the glass in a bright, warm location, such as a sunny windowsill, and change the water every few days to prevent mold and bacterial growth. Within a few weeks, small roots will emerge from the base, and new leaf growth may begin at the top. Once the roots are at least two inches long, the stalks are ready to be transferred into soil.
Starting lemongrass from seed is a much slower process and is generally less reliable for the home gardener seeking a quick harvest. The most successful approach is planting established, rooted divisions, which are small clumps taken from a mature plant. Using these rooted divisions bypasses the lengthy initial growth phase, leading to a quicker yield of usable stalks.
Optimal Conditions for Growth
Lemongrass thrives under conditions that mimic its native tropical environment, requiring a generous amount of heat and light. Full sun exposure for at least six to eight hours per day is necessary for the plant to achieve maximum size and stalk thickness. Insufficient light results in long, thin, and weaker stalks.
The soil must be rich, loamy, and consistently moist while maintaining excellent drainage to prevent root rot. Incorporating organic matter, such as compost, into the planting bed improves both the nutrient content and the soil structure. Lemongrass is a water-loving plant, and consistent, heavy watering throughout the growing season encourages the plumpest stalks.
The plant’s most rapid growth phase begins once temperatures consistently remain above 70°F. If growing in a container, select a pot that is at least 12 inches wide and deep to accommodate the extensive root system and provide stability for the tall foliage.
Cultivation Techniques for Thick Stalks
To achieve thick lemongrass stalks, the plant must be treated as a heavy feeder, particularly with nitrogen. Nitrogen is the primary nutrient responsible for robust vegetative growth, which directly translates into wider, stronger stems. Apply a high-nitrogen liquid fertilizer, such as a half-strength solution with an NPK ratio around 10-6-4, weekly or bi-weekly throughout the peak growing season (late spring through early fall).
A key technique for encouraging the base of the plant to widen is hilling. As the plant grows, periodically pile loose soil or compost around the base of the stalks, gradually mounding it up. This action encourages the buried portion of the stalk to widen and stimulates the production of new tillers, which form new, harvestable stalks.
Aggressive pruning and harvesting are essential to stimulate new growth and prevent the clump from becoming overcrowded with unproductive, woody stalks. When harvesting, select the outer stalks and pull or cut them off cleanly at the soil line. Removing older, tougher stalks directs the plant’s energy toward developing younger, tender inner stalks. Cutting back the foliage of the entire clump dramatically also forces the plant to focus its energy on new, thicker growth from the base.
Seasonal Care and Troubleshooting
Lemongrass is a frost-tender perennial that will not survive freezing temperatures, meaning gardeners in USDA Zones 9 and below must plan for overwintering. Before the first expected frost, or when nighttime temperatures consistently drop below 45°F, the plant must be prepared for dormancy. If the plant is in the ground, it should be dug up, divided, and potted, or treated as an annual and replanted the following spring.
For potted plants, the foliage should be cut back to about six inches before moving it indoors to a cool, dimly lit location, such as a basement or garage. This allows the plant to enter dormancy, requiring only infrequent watering—about once a month—just enough to keep the soil from completely drying out. If you wish to continue growth indoors, place the pot near a bright, south-facing window and reduce, but do not eliminate, watering and fertilization.
Lemongrass is generally resistant to pests, but spider mites can become an issue, particularly when the plant is grown indoors in dry air. These pests are tiny arachnids that cause fine stippling and webbing on the leaves. A forceful jet of water directed at the infested areas can dislodge many mites. For organic treatment, a spray solution of neem oil or insecticidal soap can be applied to the entire plant, focusing on the undersides of the leaves.