Detailed Explanation of the Key Technical Points for Asarum Cultivation and Management
Asarum, alias: Chinese wild ginger, pot grass wild ginger, Latin name: Asarum sieboldii Miq. Aristolochiaceae, Asarum genus perennial herb; rhizome upright or creeping horizontally, diameter 2-3 mm, internode length 1-2 cm, with multiple fibrous roots. Leaves usually 2, leaf blade heart-shaped or ovate-heart-shaped, apex acuminate or acute, base deeply heart-shaped, tip rounded, leaf surface sparsely covered with short hairs, denser on veins, leaf back hairy only on veins; stamens inserted at middle of ovary, filaments nearly equal to or slightly longer than anthers, connective prominent, short conical; ovary semi-inferior or nearly superior, spherical, relatively short, stigma lateral. Fruit nearly spherical, diameter about 1.5 cm, brownish-yellow. Flowering period April-May.
Morphological characteristics of Asarum:
Asarum is a perennial plant, plant height 15-25 cm. Underground there are horizontally creeping rhizomes, producing many slender white roots, with a strong pungent taste and aroma. The upper part of the rhizome branches, each branch has 1-2 heart-shaped leaves, length 4-12 cm, width 5-14 cm, petiole length 7-15 cm, leaves grow in clusters, a single plant may have dozens to over a hundred leaves. Flowers are solitary, emerging from between two petioles; perianth purple-red, broadly elliptical, revolute from the base; capsule hemispherical, not dehiscing at maturity, breaking open only after rotting. Seeds ovate-conical, hard-shelled, grayish-brown and glossy. Flowering period April-May, fruiting period June-July.
How is Asarum cultivated and managed?
1. Site selection and land preparation. Asarum prefers loose, fertile soil rich in organic matter, with pH preferably neutral or slightly acidic. It fears strong light and drought, so the main production areas in Northeast China mostly choose understory cultivation; when using old ginseng land or farmland for planting, shade sheds must be built. Understory cultivation has no strict requirements for tree species, but broadleaf forests are best, followed by mixed coniferous-broadleaf forests. Slopes facing east or west are preferable, with a slope preferably within 10 degrees.
Land preparation should be carried out in spring and summer; early land preparation helps soil maturation, making Asarum grow well with less disease. Before digging, remove small shrubs or overly dense branches from the forest land to maintain a 50%-60% light transmittance under the canopy, dig to a depth of 15-20 cm, remove stones and tree roots, rake the soil surface level, and make raised beds 1-1.2 m wide, 10-20 m long, and about 20 cm high; the working path should be 50-100 cm wide. Where the soil layer is thick the working path may be slightly narrower; where the soil layer is thin the working path should be wider, to ensure sufficient soil on the bed surface.
2. Propagation methods. Mainly by seed propagation, also by root division propagation.
(1) Seed propagation. The seed treatment method is to dig a shallow pit in a shaded area under the forest, about 15 cm deep, with size depending on the amount of seed; mix 1 part seed with more than 5 parts sand, place into the pit, cover with about 5 cm of sand, then cover with leaves or rice straw. Check frequently, keep warm and prevent water accumulation; after about 45 days, sow in time to avoid germination.
Sowing methods: broadcast sowing, drill sowing, and hole sowing are all acceptable. For broadcast sowing, mix seeds with 10 times fine sand or soil and scatter evenly on the bed surface, sowing about 30 g of seeds per square meter. For drill sowing, sow in rows on the bed at a row spacing of 10 cm, sowing width 4 cm, about 130 seeds per row. For hole sowing, row spacing 13 cm, hole spacing 7 cm, 7-10 seeds per hole. After sowing, cover with humus soil or sieved fine soil about 2.5 cm thick, then cover with grass or leaves about 3 cm. Keep the soil moist.
Asarum can be direct-seeded, growing in place for 3-4 years before harvesting the product. This can be adopted when seeds are abundant. At present, production areas, in order to make full use of seeds to expand planting area, mostly adopt seedling raising and transplanting. Transplanting 2-3 year old seedlings is preferable, carried out in late autumn or early spring each year after the aboveground parts wither or before seedlings sprout. The planting method is to open horizontal furrows on beds with sufficient base fertilizer, row spacing 17-20 cm, plant spacing 7-10 cm, place the seed roots well in the furrows, let the roots spread out, cover with soil to a thickness such that the bud scales are about 5 cm from the soil surface, and cover with grass or leaves on top. It can also be planted by digging holes at a row spacing of 15 cm, with 7-10 holes per row.
(2) Root division propagation. Using harvested plants, cut off a 4-5 cm section from the upper part of the rhizome, each section must have 1-2 bud scales and retain root strips, then dig holes at a plant and row spacing of 20 cm×20 cm, planting 2-3 rhizome sections per hole.
3. Field management
(1) Watering and weeding. Asarum has a shallow root system and is not tolerant of drought, especially in seedling beds; the seeds are tiny and covered with shallow soil, so soil moisture must be checked frequently, and watered promptly when the soil is dry, to ensure full and strong seedlings. Attention should be paid to timely weeding; both the beds and the furrows should be free of weeds.
(2) Regulating light. Before May, temperatures are low, and Asarum seedlings require more light, so shading is not needed. Starting from June, light should be controlled at a 50%-60% transmittance. When using old ginseng land to plant Asarum, shade sheds must be built well; for understory cultivation, boron supplementation or branch trimming should also be done according to Asarum's light requirements.
(3) Fertilizing and earthing up. Asarum is a fertilizer-loving plant; when planted in poor soil, if not fertilized, it grows extremely slowly. According to experience in Liaoning, pigsty manure is best as base fertilizer, smoked soil fertilizer (tiger manure) is second, and superphosphate is best among chemical fertilizers. In May and July each year, superphosphate 1 kg can be added to clean water 50 kg, stirred to dissolve, and the supernatant taken and poured onto the bed surface with a watering can; use superphosphate 1 kg per 20 sq m.
After winter begins, use pigsty manure 4000 kg per mu mixed with superphosphate 40 kg for fermentation together; mix the fermented fertilizer with about 5 times humus soil and spread it over the Asarum beds, which both serves to fertilize for the coming year and protects the bud scales for safe overwintering. Because the Asarum rhizome grows upward by one node each year, if the bud scales on it are not protected, they are susceptible to frost damage.
(4) Removing flower buds. Perennial plants bloom and set seed every year, consuming a large amount of nutrients and affecting yield; therefore, except for seed-producing plots, all flower buds should be removed when they emerge from the ground.