Rough ginger, Zingiber zerumbet, is a unique plant distinct from common culinary ginger. Also known as “shampoo ginger” or “pinecone ginger,” it is valued for its appearance and traditional uses.
Identifying Rough Ginger
Zingiber zerumbet is known by several names, including shampoo ginger, pinecone ginger, bitter ginger, and Awapuhi. This perennial grows from thick, creeping rhizomes, similar to culinary ginger (Zingiber officinale). Unlike culinary ginger, Zingiber zerumbet is cultivated for its unique inflorescences and other applications.
The plant features reed-like stems 4 to 7 feet tall, with lanceolate leaves 8 to 12 inches long arranged alternately. Some varieties, like ‘Darceyi’, have variegated green and white leaves. Its distinguishing pinecone-shaped inflorescence emerges on separate, shorter stalks directly from the rhizomes, often concealed beneath leaf stalks. These inflorescences are initially green and waxy, maturing to a vibrant red and filling with a clear, fragrant liquid. During cooler fall and winter, the plant becomes dormant, with above-ground parts dying back, leaving only underground rhizomes.
Traditional and Modern Applications
Rough ginger has a long history of traditional use in Asia and the Pacific Islands. Its rhizomes, leaves, and inflorescences have all been utilized. The viscous liquid from mature, red inflorescences is famously used as a natural shampoo and conditioner, making hair soft and shiny. This “ginger shampoo” is highly valued, and the liquid can be gently squeezed from the cones for direct application.
Beyond cosmetics, the plant’s rhizomes have been used in traditional medicine for various ailments. Historically, rough ginger addressed inflammation, fever, toothache, stomach issues, allergies, and skin diseases. It also alleviated digestive problems like indigestion, constipation, and diarrhea. The dried rhizome has also been ground into a powder for perfume.
Modern scientific research investigates Zingiber zerumbet’s pharmacological properties, focusing on its main bioactive compound, zerumbone. Studies show anti-inflammatory, antioxidant, anti-diabetic, and antimicrobial effects. The plant also shows potential for anticancer, analgesic, and immunomodulatory properties in preclinical studies. While edible, the rhizomes have a bitter taste compared to culinary ginger, though leaves flavor dishes in some cuisines.
Growing and Harvesting Rough Ginger
Cultivating rough ginger is achievable for home gardeners in suitable climates. This tropical perennial thrives in warm, humid conditions and prefers partial shade, tolerating full sun if soil remains consistently moist. Choose a site with well-draining, fertile soil, ideally with a slightly acidic to neutral pH (5.7 to 8.0). Amending soil with compost or manure enhances fertility.
Propagation is most effective by dividing rhizomes in spring or early summer. Each rhizome section needs at least one growing shoot or “eye.” Plant rhizomes horizontally just below the soil surface, spacing them 2 to 3 feet apart to allow for spreading. For containers, ensure good drainage and use a rich potting mix.
Rough ginger requires consistent moisture, needing at least one inch of water per week during its active growing season (late spring to late fall). Keep soil moist but not waterlogged to prevent rot. Fertilize with a balanced fertilizer every 4-6 weeks during the growing season. As the plant goes dormant in winter, reduce watering significantly. In colder zones (below USDA Zone 8), rhizomes may need to be dug up and stored indoors to protect from frost.
Harvest the “shampoo” liquid when cones are fully red and filled with clear, fragrant liquid. It can be gently squeezed out. Cones can refill overnight if not squeezed too hard, or be fully squeezed for a larger yield. For medicinal or culinary use, rhizomes can be dug up after about 10 months, then washed and used fresh or dried.
Precautions and Responsible Use
When considering rough ginger, particularly for medicinal use, be aware of potential considerations. While generally well-tolerated, some animal studies reported adverse effects at certain dosages, including appetite loss, behavioral changes, and skin discoloration. However, other studies with higher doses did not observe these effects, suggesting reactions might be dose-dependent or vary by preparation.
Consult a healthcare professional before using Zingiber zerumbet or any herbal remedy, especially with pre-existing health conditions or other medications. This avoids potential interactions or contraindications.
When sourcing rough ginger, whether from a garden or wild foraging, responsible practices are important. The plant can spread aggressively by rhizomes in some climates, so growing it in containers can help manage its spread. If foraging, ensure sustainable harvesting to maintain plant populations.