Lemongrass (Cymbopogon citratus) is a fragrant, perennial herb prized for its culinary uses and ornamental qualities. Native to tropical regions, it thrives in warm climates, making understanding its temperature needs essential for successful cultivation.
Optimal Temperature Range for Lemongrass
Lemongrass grows best in consistently warm conditions, ideally with temperatures ranging from 68°F to 100°F (20°C to 38°C). A range of 70°F to 90°F (21°C to 32°C) is optimal for robust growth during the growing season. These warm temperatures promote vigorous foliage development and strong root systems.
Maintaining temperatures above 68°F (20°C) supports continuous growth and prevents stress or dormancy. This consistent warmth is beneficial for developing the thick, flavorful stalks used in cooking.
Protecting Lemongrass from Cold
Lemongrass is sensitive to cold and vulnerable to frost. Temperatures below 55°F (13°C) can be detrimental, and anything approaching 40°F (4°C) is too cold, potentially causing damage or killing the plant. At 15°F (-9°C), lemongrass freezes to death.
Signs of cold stress include leaves lightening in color, turning brown or black, and exhibiting wilting and drooping.
For those in colder climates (USDA Zones 9 or below), bringing potted lemongrass indoors before the first frost is necessary. If growing in the ground, plants can be dug up, trimmed to a few inches, and potted for overwintering.
Mulching around outdoor plants with straw or wood chips can help insulate roots and maintain consistent soil temperatures in milder Zone 9 areas. Harvesting all usable stalks before the first hard frost is an option for plants that cannot be overwintered.
Managing Lemongrass in Hot Conditions
Lemongrass tolerates high temperatures well, thriving in full sun even in hot southern locations. It is well-adapted to significant heat, with optimal growth extending up to 100°F (38°C). While it can endure heat, extreme conditions, especially with insufficient water, can still cause stress.
Providing consistent moisture is crucial in hot weather, as it is not drought-tolerant and needs regular irrigation. Watering once or twice weekly, or even daily for potted plants in very hot conditions, helps prevent the soil from drying out.
In areas with intense midday sun and extreme heat, offering some afternoon shade can prevent overheating and maintain plant health. Signs of heat stress might include stunted growth or crispy leaf tips, indicating a need for more consistent watering or a slight reduction in direct sun exposure during peak heat.