Glycyrrhiza glabra (Licorice)
Glycyrrhiza glabra (Licorice)
Contents
Introduction & History
Licorice is the herb with the most recognisable flavour in the world — that sweet, anise-like taste that's 50 times sweeter than sugar comes from the root of this unassuming, leguminous perennial. Used for over 5,000 years from China to Egypt, licorice root remains one of the most important herbs in both traditional Chinese medicine and modern food manufacturing.
History & Origin
Native to southern Europe and western Asia. One of the oldest and most widely used medicinal herbs — found in the tomb of Tutankhamun (1323 BCE), documented in Chinese medicine since at least 2100 BCE, and described by Theophrastus (300 BCE). Liquorice ('liquiritia' from Greek 'glykyrrhiza' = sweet root) has been cultivated commercially in England since the 16th century (Pontefract, Yorkshire). It remains one of the most traded herbs globally.
Botanical Description
Herbaceous perennial growing 60–120 cm tall with an extensive, deep root system. Leaves are pinnate with 9–17 oval leaflets — typical legume foliage. Small, pale violet-blue flowers in short spikes appear in summer, followed by small, flattened seed pods. The magic is underground: thick, woody, sweet-tasting roots and runners (stolons) spread extensively, making the plant difficult to remove once established.
Stem: Semi-woody to woody at base • Height: 100 cm at maturity • Spread: 60 cm • Foliage: green • Flowers: blue-purple (summer)
Planting & Cultivation
Plant root divisions or nursery specimens in spring, spacing 45–60 cm apart. Full sun, deep, sandy, well-drained soil. The deep root system needs at least 60 cm of unrestricted soil depth. Seed is slow and unreliable — root divisions are the standard planting method. Position where the spreading root system won't interfere with other plants. Harvest roots at 3–4 years.
| Sun exposure | Full Sun |
| Soil pH | 6.0-8.0 |
| Spacing | 60 cm |
| Seed depth | 3–6 mm (surface-sow if light-dependent germinator) |
| Water needs | Moderate |
| Soil type | Well-drained, humus-rich loam; add perlite or grit for drainage |
Cultivation Details
Full sun, deep, sandy soil with good drainage. The root system is extensive — both deep (1–2 metres) and spreading (stoloniferous). This can be invasive in ideal conditions. Contain the root spread with deep barriers or grow in large, deep containers. Requires warm summers for best root development. Minimal above-ground maintenance. Feed lightly with low-nitrogen fertiliser.
Climate & Hardiness
Hardy to about −20°C (USDA zones 5–9). Needs warm, dry summers for best root sweetness (the plant's native habitat is semi-arid Mediterranean to Central Asian steppe). In cool, wet climates, root quality is lower. Commercial production occurs in Turkey, Iran, China, and southern Europe — hot, dry summers are key to quality.
USDA zones: 7-10
Minimum temperature: -10°C
Drought tolerance: Yes — established plants tolerate dry spells
Seasonal Care
Spring: new shoots emerge; divide if needed. Summer: the unremarkable foliage grows. Autumn: harvest roots from 3–4 year plants. Winter: fully dormant; cut back dead growth.
Propagation
By root division in spring — each piece with a bud will grow. By stolon segments. Seed is viable but germination is slow and erratic (scarification helps). Root division from established plants is far more practical. The spreading stolons naturally propagate the plant.
| Method | Success rate | Time | Notes |
|---|---|---|---|
| Stem cuttings | 70–90% | 2—4 weeks | Softwood in spring, semi-ripe in summer; 8–12 cm |
| Division | 95%+ | Immediate | Split established clumps in spring or autumn |
| Seed | 50–80% | 14–28 days | Some require cold stratification; germination variable |
| Layering | 80–90% | 6–12 weeks | Pin low branch to soil; sever when rooted |
Diseases & Pests
Generally healthy. Aphids on young growth. Spider mites in dry conditions. Powdery mildew occasionally. Root rot in waterlogged soil. As a legume, it fixes nitrogen through root nodules — a benefit to the soil. No serious pest problems.
Culinary Uses
The sweet root is used in confectionery (liquorice candies, particularly in Scandinavia and the Netherlands), brewing (stouts and porters), herbal teas, and as a natural sweetener. Essential flavouring in anise-flavoured spirits: ouzo, arak, sambuca, and pastis. In Chinese cooking, it's used in five-spice powder and slow-braised dishes. Chewing a root stick is a natural breath freshener and was historically used as a 'chew stick' toothbrush substitute.
Medicinal & Aromatherapy
Contains glycyrrhizin (50× sweeter than sugar), flavonoids, and isoflavones. Used in traditional Chinese and Ayurvedic medicine for thousands of years — as a harmonising herb that makes other medicines more effective. Documented anti-inflammatory, antiviral, and expectorant properties. Soothes sore throats and digestive irritation. CAUTION: excessive consumption (>50 g/day for extended periods) can cause hypertension, hypokalaemia, and fluid retention due to the mineralocorticoid effect of glycyrrhizin.
Container & Companion Growing
Container Growing
Challenging but possible in very deep containers (50+ cm). The root system needs depth. Use sandy, well-draining compost. Full sun. Water moderately. Container growing helpfully contains the spreading stolons. The above-ground plant is unremarkable — grow for the root harvest rather than visual appeal.
• Minimum pot size: 25–35 cm Ø, 10 L+
• Depth depends on root type
• Use free-draining potting compost with 20–30% perlite or grit
• Ensure drainage holes; stand on pot feet to prevent waterlogging
• Feed with dilute liquid fertiliser (half-strength) every 2–3 weeks in growing season
Companion Planting
As a nitrogen-fixer (legume), licorice improves soil fertility for neighbouring plants. In permaculture, useful in guild plantings under fruit trees. The spreading root system can be problematic near other plants — contain or give it its own bed. Not typically used as a vegetable garden companion due to the spreading roots.
| ✓ Good companions | Most vegetables, Fruit trees |
| ✗ Avoid planting with | Other vigorous herbs |
Common Mistakes to Avoid
Not giving it deep enough soil for the extensive root system. Not containing the spreading stolons. Harvesting too early (wait 3–4 years for meaningful root mass). Consuming excessive amounts (the health warnings are real — moderation is key). Not realising how deeply the roots penetrate — digging them up is hard work.
Harvesting & Preservation
Harvest roots in autumn from 3–4 year plants. Dig deeply and carefully — the roots extend far. Wash, slice, and dry slowly (the dried root keeps its sweetness for years). Chew dried root sticks as a natural sweet. For tea, simmer dried root pieces in water for 10–15 minutes (a decoction, not an infusion). Store dried root in sealed containers.
• Time of day: Early morning, after dew has evaporated but before intense midday heat volatilises essential oils
• Growth stage: Just before flowering, when essential oil concentration peaks. Once flowers open, the plant redirects energy from leaf production
• Season: Autumn (3-4 Years)
• Part harvested: Roots
• Harvest rule: Never remove more than ⅓ of the plant at once; this ensures continued vigorous regrowth
• Technique: Cut stems cleanly above a leaf node with sharp scissors or secateurs. Tearing damages tissue and invites disease
| Method | Process | Shelf life | Best for |
|---|---|---|---|
| Air drying | Tie bundles, hang upside down in warm, dark, airy space | 6–12 months | Most herbs |
| Oven / dehydrator | Spread on trays, 35–45°C until crisp | 6–12 months | Fleshy-leaved herbs |
| Freezing (whole) | Blanch 5s, ice bath, pat dry, freeze flat on tray | 6 months | Basil, chives, parsley |
| Freezing (oil cubes) | Chop fine, pack into ice cube tray, cover with olive oil | 6 months | Any culinary herb |
| Herb salt | Layer herb and coarse salt 1:4, dry and grind | 12+ months | Rosemary, thyme, sage |
| Infused vinegar | Pack jar, cover with warm vinegar, steep 2–4 weeks | 6 months | Tarragon, dill, basil |
| Infused oil | Fill jar with dried herb, cover with oil, steep 4–6 weeks | 3–6 months | Rosemary, thyme, chilli |
Frequently Asked Questions
Is it safe to eat licorice?
In moderate amounts, yes. Excessive consumption of real licorice (not artificially flavoured candy) — more than 50 g daily for weeks — can raise blood pressure and lower potassium levels. People with hypertension, heart conditions, or kidney disease should limit intake. Most commercial 'liquorice' candy uses artificial flavouring, not real licorice root.
How long until I can harvest roots?
3–4 years for worthwhile root mass. The longer you wait (up to 5–6 years), the larger and sweeter the roots. This patience requirement is the main challenge for home growers.
Can I just chew the root?
Yes — dried licorice root sticks are traditionally chewed as a natural sweet and breath freshener. The sweetness is released slowly and the woody texture provides dental exercise. It's how licorice was consumed for millennia before candy manufacturing.
Seasonal Care Calendar
🌱 Spring (Mar–May)
Water: Light
Feeding: Light feeding
☀️ Summer (Jun–Aug)
Water: Moderate
Feeding: No feeding
🍂 Autumn (Sep–Nov)
Water: Minimal
Feeding: No feeding
❄️ Winter (Dec–Feb)
Water: Minimal
Feeding: No feeding
The world's most recognisable herbal flavour — roots 50× sweeter than sugar. Leguminous perennial with deep, spreading roots. Hardy to −20°C (zones 5–9). Harvest at 3–4 years. Used in candy, spirits, and 5,000 years of medicine. Caution: excessive consumption causes hypertension.
Quick Reference: Glycyrrhiza glabra
Key Principles: Right location, well-drained soil, regular harvesting to promote growth, and appropriate winter protection for tender species.