Detailed Guide to Asarum Cultivation Techniques: Key Points on Planting and Management Methods

Asarum Cultivation Techniques

Asarum is a precious authentic Chinese medicinal herb from Liaoning, with wide distribution, high yield and good quality, selling well both domestically and abroad. Xinbin County began developing artificial cultivation of asarum in 1986, and now more than 20,000 hectares remain in production. With high economic returns, it is one of the main varieties for farmers to prosper and a major cultivated Chinese medicinal herb. Asarum is used medicinally as the whole plant, pungent in taste and warm in nature. It has the functions of dispelling wind and dispersing cold, and opening the orifices to stop pain. It mainly treats wind-cold headache, sinusitis, toothache, phlegm-retention cough, and wind-damp arthralgia; recently it has also been used to treat rhinitis, laryngitis, gastritis and oral erosion, all with notable efficacy.

I. Growth Habits of Asarum

Asarum is a shade-loving plant, mostly distributed in mountain areas with deep humus layers and fertile soil under broadleaf forests and mixed coniferous-broadleaf forests, or growing among dense shrubs, in slightly moist spots at the bottom of gullies and along forest edges. Thus it has developed characteristics of liking moisture, liking fertilizer, liking shade, and fearing strong light, but under forest canopy with excessive closure it grows extremely slowly. Practice has proven that only through "dappled shade" or ample scattered light combined with strengthened water and fertilizer management can asarum grow rapidly and achieve high yields.

II. Asarum Seedling Cultivation Techniques

1. Site selection The site for asarum can be chosen under forest or on ginseng-following land or garden land with a shade shed. For forest planting, broadleaf forest or mixed coniferous-broadleaf forest should be chosen, preferably a plot with suitable light transmittance, flat terrain, good drainage and fertile soil. For non-forest cultivation of asarum, it is best to choose a place with irrigation conditions, preferably flat terrain, loose and fertile soil with good drainage. Clay soil with poor permeability, overly sandy wind-leaking land, and low-lying areas or dry ridge land with shallow soil are all unsuitable.

2. Land preparation For cultivating asarum under forest, first cut clean the underbrush and remove it from the site, then rake out stones and other debris, and begin digging. The depth depends on the depth of the soil layer; do not dig out the raw subsoil. Generally 5-20 cm deep is sufficient. After the first digging, rake once more to remove grass and roots from the field, then after raking level, dig again carefully to remove remaining grass and fibrous roots from the soil. After raking clean and level, beds can be made. When using farmland or garden land to cultivate asarum, first plow the land (20-30 cm deep), break up clods, apply 2000-3000 kg of pig manure per 667 sq m, turn the manure into the soil and mix well, rake level and refine, then make beds.

3. Bed making The method of making asarum beds is simple and easy. Make beds along the slope or slightly angled to the slope; do not make beds across the hill to prevent rain erosion. Generally the bed width is 1.2 m, height 20 cm, and the length can be determined by the terrain, generally 10-30 m is suitable; if too long it is difficult to level. The working path is 0.8 m wide. Under forest with fertile soil, generally no base fertilizer is applied.

4. Sowing The characteristic of asarum seeds is that dry seeds do not easily emerge; after harvest they should be sown fresh. Otherwise, as the dry storage time lengthens, germination capacity gradually decreases. Experiments have shown that fresh seeds can reach a germination rate of 96%, while after 60 days of dry storage the germination rate drops to 2%; if stored dry even longer, no seedlings will emerge at all after sowing. Timely sowing is the key to improving germination rate and ensuring full stands. After seed collection, if soil moisture is good, sow immediately. Generally this is done from late June to early July, no later than the end of July, otherwise root growth is affected.

Sowing is divided into 4 methods: broadcast sowing, drill sowing, hole sowing and whole-fruit sowing. The broadcast sowing method involves making a shallow bed trough about 3 cm deep on the bed surface, scraping the bottom level, then evenly broadcasting fresh seeds mixed with 5 times their volume of fine sand into the trough, then covering with 2 cm of sieved humus soil, requiring uniform soil cover. Broadcast sowing produces uniform seedlings, each plant has a certain nutritional area, which is beneficial to growth. However, the seedling's ability to push through the soil is weak; if the soil crusts it is difficult for seedlings to emerge, and weeding requires much labor. It is suitable for sowing on ginseng-following land and loose fertile forest land. The drill sowing method involves opening horizontal furrows on the bed surface at 10 cm row spacing, 3 cm deep, sowing 120-150 seeds per row with about 1 cm seed spacing, covering with 2 cm of soil. About 250 g of seed is used per seedbed curtain. Drill sowing is suitable for seedling cultivation in garden land; seeds are relatively concentrated, easy to push through the soil and emerge, convenient for loosening soil and weeding, but produces fewer seedlings. The hole sowing method involves digging holes on the bed surface for sowing, with row spacing of 9-12 cm, hole spacing of 6 cm, sowing 7-10 seeds per hole, covering with 2 cm of soil; the seeding rate is close to drill sowing. The whole-fruit sowing method involves digging holes on the bed surface and sowing whole fruits, with row spacing of 9-12 cm, hole spacing of 8-10 cm, covering with 2 cm of soil after sowing. Whole-fruit sowing wastes seed, requiring 700 g per curtain and 21 kg per 667 sq m. Hole sowing and whole-fruit sowing have strong soil-pushing ability and are suitable for relatively compacted soil, but seedlings emerge clustered together which affects growth, roots easily become tangled, and transplanting is difficult, so they are generally not used. After sowing, cover the bed surface with a layer of dead branches and fallen leaves or rice straw to maintain moisture, prevent surface crusting and rain erosion.

5. Seedling stage management After sowing asarum, in the first year only roots grow and no seedlings emerge. In the following spring, before seedlings emerge in early April, remove the covering to ventilate and light the bed surface, raise soil temperature and promote emergence. If there is spring drought, remove the covering a bit later, or after removal water with a sprinkling can to help emergence. In the second year after sowing, asarum seedlings grow weakly, with only two leaves all year, so field management must be strengthened, with frequent loosening of soil and weeding. Before overwintering, where conditions permit, a layer of pigsty manure can be spread to help prevent cold and preserve moisture, and also serve as topdressing. For seedling cultivation outside forest, leafy branches or old ginseng curtains can be used to build a shade shed.

III. Transplanting

The time for transplanting asarum is generally divided into spring and autumn, that is, mid-to-late May or mid-to-late October. Spring planting is done before the buds sprout, and autumn planting after the overwintering buds have formed; autumn planting is preferable. Asarum transplanting methods include wild seedling transplanting, seedling transplanting, and terminal bud propagation.

Here we mainly introduce the seedling transplanting method.

1. Seedling selection In order not to affect the next year's growth, seedlings should be selected before transplanting, choosing asarum with fresh, disease-free leaves as planting stock, discarding soft, rotten, blackened and overly wilted seedlings, to ensure vigorous growth of the transplants.

2. Planting method The furrow drill planting method is suitable for planting artificially cultivated 2-3 year old seedlings. Open horizontal furrows 10 cm deep on the bed surface, with row spacing of 20 cm and plant spacing of 4-6 cm. Arrange the roots in a fan shape and spread them out, then cover with 4 cm of soil. Afterwards cover the bed surface with fallen leaves or rice straw to keep the soil moist and prevent crusting, and also to protect against cold and freezing. Each 667 sq m requires 40,000 seedlings. If drought occurs, water half an hour after covering with soil; after the water seeps down, cover again with soil up to bed level. The furrow hole planting method involves opening horizontal furrows 14 cm deep on the bed surface, planting 6 holes per row, with 2 large seedlings or 3-4 small seedlings per hole, and hole spacing of 20 cm. Begin planting from the upper end of the bed, scraping soil toward the downhill direction, with the asarum rhizome tip tilted toward the uphill direction, do not let roots curl, and cover with 20 cm of soil. If soil moisture is poor, water when half the soil cover is done, and after the water seeps down, level the bed surface with the remaining soil. This method is suitable for planting wild seedlings.