Licorice (Glycyrrhiza glabra) is a perennial herb known for its distinctively sweet roots. Historically, it has been used across various cultures for both culinary and medicinal purposes. Its roots contain glycyrrhizin, the compound responsible for its characteristic sweetness.
Understanding Licorice Growing Zones
Successful licorice cultivation requires understanding its preferred growing environment, especially USDA Plant Hardiness Zones. Licorice thrives as a perennial in USDA Zones 7 through 10. Gardeners in Zone 6 might also achieve success, though heavy mulching for winter protection is recommended.
These zones delineate regions based on average minimum winter temperatures, indicating where a plant can survive the cold season. Licorice can tolerate brief periods as low as 5°F (-15°C), though prolonged exposure is not ideal. Local microclimates, influenced by factors like elevation and nearby structures, can also affect a plant’s ability to flourish.
Ideal Climate Conditions for Licorice
Beyond hardiness zones, other climatic factors influence licorice growth. The plant thrives in full sun, requiring at least six hours of direct sunlight daily for optimal root development. While it can tolerate partial shade, insufficient light may result in weaker growth and less robust root systems.
Licorice prefers moderate temperatures for active growth, ideally ranging between 60-85°F (15-30°C). During the growing season, consistent moisture is beneficial, though the plant is sensitive to waterlogging. Once established, its deep root system provides some drought tolerance, but it still needs watering every few days during hot, dry spells.
Soil and Site Preparation
Proper soil and site preparation are essential for healthy licorice plants. Licorice prefers deep, loose, and well-draining soil, with a sandy loam composition being ideal. Its extensive root system necessitates a soil depth of at least 12 inches for proper development.
A slightly acidic to neutral or mildly alkaline soil pH, ranging from 6.0 to 7.5, supports optimal growth. Good drainage is essential to prevent root rot. If your soil is heavy clay, amending it with organic matter like compost, well-rotted manure, and sand will improve drainage and structure.
Cultivation and Ongoing Care
Once the ideal site is prepared, licorice can be planted from seeds or root cuttings. For seeds, cold stratification for two to four weeks, followed by a 24-hour soak in water, can enhance germination rates. When planting, ensure ample space, as each seedling can eventually require about 20×20 inches (50x50cm).
Consistent moisture is important, especially during dry periods, but allow the top layer of soil to dry slightly between waterings to prevent root rot. Licorice has light fertilization needs; if planted in nutrient-rich soil, a single annual application of organic, slow-release fertilizer or compost in spring is sufficient. The plant is resistant to most pests and diseases, though root rot can occur with poor drainage. Slugs or spider mites may also appear.
Harvesting and Utilization
Licorice roots are ready for harvest after two to three years. Some sources suggest waiting three to four years to ensure sufficient root mass has developed. The best time to harvest is in autumn, after the plant has blossomed or begun to die back, as the roots are at their sweetest during this period.
To harvest, carefully dig up the entire plant, or extract the horizontal roots while leaving the main taproot to encourage continued growth. After digging, thoroughly wash the roots to remove soil and then scrape off the outer skin. The cleaned roots can be cut into smaller pieces and dried for future use, though the drying process can make them very hard. These harvested roots can be used for tea, extracts, or as a culinary flavoring in sweets and baked goods.