Lemongrass (\(Cymbopogon citratus\)) is a fragrant, tropical herb prized globally for its distinct citrus flavor in culinary dishes and teas. This grass-like plant forms dense clumps and thrives in long, hot growing seasons, leading gardeners to question its hardiness in cooler climates. USDA Hardiness Zone 8 is defined by average annual minimum temperatures ranging between 10°F and 20°F. This challenging environment puts lemongrass on the edge of survival, requiring special intervention to maintain it year after year.
Defining Perennial Status in Zone 8
Lemongrass is classified as a tender perennial, capable of living for more than two years but lacking the hardiness to withstand freezing temperatures. The plant’s root crown, where the stems meet the roots, is susceptible to cold damage and typically dies when temperatures fall below 25°F for a sustained period. Its reliable perennial range begins in USDA Zone 10 or 11, where frost is rare or non-existent.
In Zone 8, the plant is considered marginally hardy and, without intervention, is generally treated as an annual that must be replanted each spring. While the average minimum temperature range of 10°F to 20°F is survivable for brief periods, a prolonged cold snap will destroy the plant’s underground structure. Survival is not guaranteed even with protection, especially in Zone 8a, which experiences colder minimums compared to 8b. Variability in microclimates, such as protection from a south-facing wall or a thick layer of snow, can sometimes allow the roots to survive down to 15°F.
Essential Summer Growing Care
To ensure a lemongrass plant has the best chance of surviving a Zone 8 winter, it must establish a robust root system during the active growing season. This requires positioning the plant in a location that receives a minimum of six hours of direct sunlight daily. Full sun exposure is necessary to maximize photosynthesis, which leads to the production of flavorful essential oils.
The soil must be rich in organic matter and possess excellent drainage. Lemongrass is adapted to moist conditions but will quickly rot if its roots sit in soggy soil, so amending dense clay with compost and sand is often necessary. During the heat of summer, plants require consistent watering to keep the soil evenly moist, especially in containers, but the goal is hydration, not saturation.
Lemongrass is a heavy feeder due to its rapid growth habit and benefits from regular fertilization throughout the warm months. Applying a balanced, water-soluble fertilizer every two to three weeks encourages the development of thick, healthy stalks that store energy reserves needed for dormancy. A formula with a slightly higher nitrogen content is beneficial to support the extensive foliage growth.
Overwintering Strategies
Because Zone 8 presents a cold risk, gardeners must choose a proactive strategy to protect the root crowns from freezing temperatures. The most reliable method is to treat the plant as a container specimen, allowing for easy movement indoors when nighttime temperatures consistently drop below 50°F. If the plant is too large, it should be dug up, divided, and potted into a container with adequate drainage holes.
If keeping the plant actively growing, potted lemongrass can be placed near a bright, south-facing window. During this time, the plant’s growth will slow, requiring significantly less water—only enough to prevent the soil from completely drying out. Fertilizing should be suspended until new growth resumes in the spring, as the plant is not actively utilizing nutrients.
An alternative approach is to force the plant into dormancy by lifting the entire root clump from the ground before the first hard frost. The foliage should be trimmed back to six to twelve inches to minimize moisture loss during storage. The trimmed root ball can then be placed into a container with lightly moistened potting soil and stored in a dark, cool location, such as a garage or basement, where temperatures remain above freezing but below 50°F.
Overwintering the plant directly in the ground is the riskiest method, only advisable in the warmest microclimates of Zone 8. If attempting this, the crown must be covered with a substantial layer of insulating mulch, ideally six to twelve inches deep, such as straw or shredded leaves. This thick layer helps stabilize the soil temperature and prevent the immediate root zone from experiencing a hard freeze.