How to Grow Corydalis yanhusuo? The Latest Cultivation Techniques and Methods Tutorial

Corydalis yanhusuo, also known as Yanhusuo, is a perennial herbaceous plant of the genus Corydalis in the Papaveraceae family. Its dried tubers are used as medicine, and it has the effects of invigorating blood and dissolving stasis, regulating qi and relieving pain. The "Leigong Paozhi Lun" records“for heart pain that feels like death, quickly seek Corydalis yanhusuo”. The "Compendium of Materia Medica" records: “Yanhusuo can move stagnant qi within the blood and stagnant blood within the qi, so it specifically treats all kinds of pain throughout the body. When used appropriately, its effects are indescribably wonderful.”

 Botanical Characteristics of Corydalis yanhusuo

Corydalis yanhusuo is a perennial herb with stems 10~20 cm tall. The tuber is spherical, yellow inside. The aboveground stem is slender and slightly fleshy, bearing 3~4 leaves. The leaves are bipinnately ternately parted, with the final segments lanceolate or narrowly ovate. The inflorescence is a raceme, with ovate bracts; the sepals are extremely small and shed early; the petals are purplish-red, 4 in number, arranged in two whorls. The two outer petals are slightly larger, with the outermost one extending at the base into a long spur; the two inner petals are narrow and small, fused. There are six stamens, diadelphous. The ovary is superior, composed of two carpels forming one locule. The fruit is a capsule, flat and columnar. The flowering period is March to April, and the fruiting period is April to May.

Biological Characteristics of Corydalis yanhusuo

Corydalis yanhusuo originally grows in mountainous areas, sparse woodlands or grassy areas at forest edges. It prefers a warm and humid climate and fears strong light exposure. It is afraid of drought but can tolerate cold. Its growing season is short, and it has relatively high fertilizer requirements. Strong winds are unfavorable to its growth.

The root system of Corydalis yanhusuo is relatively shallow, mostly concentrated in the topsoil layer at a depth of 1~3 cun. The tuber generally has 1~2 buds, sometimes 3~4, and sometimes only one. A ground temperature of 18~21°C is the optimum temperature for sprouting. In the Hanzhong region, seedlings generally begin to emerge after the Start of Spring (early February) and emergence ends around the Rain Water solar term (late February). In most parts of the country, emergence occurs from late January to early February.

Before the emergence of Corydalis yanhusuo seedlings, the underground stem has already begun to elongate, growing slightly upward along a horizontal direction. The first stem node forms in late November, and by early February the underground stem has finished elongating. Each seed tuber can produce 2~4 underground stems, and each stem has 2~5 stem nodes.

From sowing to emergence, the underground stem growth stage of Corydalis yanhusuo requires 100~120 days, after which comes the tuber formation stage. The formation of Corydalis yanhusuo tubers occurs in two locations. First, they form from the swelling of the nodes of the underground stem, commonly called “daughter Yanhusuo”. Usually, under fine planting and sufficient fertilization, planting one Corydalis yanhusuo tuber can form more than 10 daughter Yanhusuo from the swollen nodes of its underground stem. However, if fertilization is insufficient and planting is extensive, planting one Corydalis yanhusuo tuber can produce only 5~8 daughter Yanhusuo. Second, they develop from the tissues of the seed stem, commonly called “mother Yanhusuo”. Mother Yanhusuo begins to form in early February and finishes by late February. The “daughter Yanhusuo” begins to form as the stem nodes swell at the growing nodes, and this takes about 50 days, that is, from mid-to-late March to late April is the period of stem node swelling. Especially from late March to mid-April is the peak period of new tuber growth. The growth condition of Corydalis yanhusuo during this period directly affects the harvest yield.

Corydalis yanhusuo is a typical sun plant. It grows relatively quickly and has a relatively short lifespan (short growth cycle). From sowing to harvest is only about 210 days, and the actual growth period is only about 100 days. Therefore, applying sufficient basal fertilizer, promptly topdressing, and ensuring adequate supply of water and fertilizer during the growth period play a decisive role in increasing yield. In the original production area of Dongyang County, Zhejiang, medicinal farmers believe that the best weather for the peak growth period of Corydalis yanhusuo in early spring is “three sunny days and three rainy days” (that is, one rainfall per week), which is most suitable for its growth. Therefore, if early spring drought occurs (especially from March to April), irrigation must be provided promptly (maintaining once a week), which is the key to achieving high yield.

Based on the above, combined with research on national Corydalis yanhusuo production experience data, the living habits of Corydalis yanhusuo can be simply summarized in three phrases: the “three likes” (likes sunlight, likes warmth, likes moisture), the “three fears” (fears waterlogging, fears drought, fears continuous cropping), and the “five nots for planting” (① heavy clay yellow soil and alkaline soil cannot be planted; ② low-lying waterlogged fields are not planted; ③ continuous cropping fields are not planted; ④ areas without irrigation and drainage conditions are not suitable for planting; ⑤ seed stems without disinfection cannot be planted). Carefully selecting a suitable growing environment and strictly controlling the “five gates” are very important for improving the per-unit yield of Corydalis yanhusuo.

Cultivation Techniques for Corydalis yanhusuo

The cultivation techniques for Corydalis yanhusuo can be summarized in four phrases: “a little shallower, a little sparser, a little warmer, a little wetter”. By a little shallower, the planting (soil covering) depth should be 2 cun; by a little sparser, the sowing density should be 2.5 cun square or with a row spacing of 2×3 cun; by a little warmer, warmth must be maintained for overwintering in winter; by a little wetter, the bed surface must be kept moist and not too dry.

1. Land Selection, Preparation and Bed Making

① Land selection. For planting Corydalis yanhusuo, choose fertile land (fields) with deep soil layers, good irrigation and drainage, and relatively high soil organic matter content. Sandy loam is suitable, with sandy mud, half-sand half-mud fields, and alluvial soil being best. Dead yellow mud, white clay soil, and gravelly soil are all unsuitable for planting. The soil physical and chemical properties should be neutral or slightly acidic, usually with a pH of about 5.6-7.5.

The root system of Corydalis yanhusuo is mainly distributed at a depth of about 1-3 cun in the topsoil. The looser the soil, the more developed the root system, which is beneficial for stem node swelling and nutrient absorption; the daughter Yanhusuo will be larger and more numerous, and the yield will be higher. Compacted soil is not conducive to the growth and spreading of stems and branches, the stem nodes will be small, and the yield will be low. If the soil is too alkaline, it is easy to form stiff seedlings, growth will be slow, and the fibrous roots (stems and branches) will shrink. If the soil is too sandy, its water and fertilizer retention capacity is poor, and early senescence is likely to occur; also, because sandy soil absorbs heat too strongly, the diurnal temperature difference is large, and the ground temperature exceeds the environment required by the crop, inhibiting growth.

② Land preparation. After selecting the field for planting Corydalis yanhusuo, fine tillage must first be carried out. Plow three times and harrow three times to make the topsoil loose and fine loam; this is the foundation for achieving increased yield of Corydalis yanhusuo. If there are many large clods in the Corydalis yanhusuo field, it will not only affect emergence but also hinder root growth, seriously reducing the next year's yield. When preparing the Corydalis yanhusuo field, sufficient basal fertilizer should be applied. Because Corydalis yanhusuo has shallow roots and likes fertilizer, and its growing season is short, applying sufficient basal fertilizer is the key to increasing yield. According to analysis of large-scale high-yield experience, applying 3000 jin of decomposed pig and cattle pen manure, 100 jin of oil cake fertilizer, and 100 jin of phosphate fertilizer per mu can achieve a relatively good yield. If oil cake fertilizer is applied excessively or undecomposed fertilizer directly contacts the seed stems, it will cause seedling burn; although the seed stems will not change color or rot, the buds stop growing after sprouting 1-2 cm. If too much nitrogen fertilizer is applied, it will cause excessive vegetative growth of stems and leaves, and they may lodge in patches during heavy rain, creating favorable conditions for downy mildew spores to parasitize and reproduce, causing large-scale death after infection and reducing yield. Therefore, when applying oil cake fertilizer, fermenting it in advance is beneficial for full absorption by the Corydalis yanhusuo root system.

③ Bed making. After the field is prepared, make beds immediately. Usually, making beds in the transverse direction is preferable, which is beneficial for irrigation and drainage. At the same time, shorter bed surfaces are easier to level, which can improve land utilization. When beds are made reasonably, the utilized area of one mu of land is about eight fen. Generally, the bed width is 4 chi, the ditch width is 7 cun-1 chi, and the ditch depth is 5-7 cun. The specific bed making is shown in the diagram:

2. Planting Time and Methods

① Planting time. Corydalis yanhusuo is propagated by tubers, has a short growth period, and occupies only the time equivalent to one season of wheat. It has large returns, high yield, and quick results. The high-yield planting period is between the Autumn Equinox and Cold Dew (that is, late September to early-to-mid October). Production areas have the experience that “planting early is better than applying fertilizer once”. If planting is delayed until after Frost's Descent, the underground stem will have less than 100~120 days of growth before emergence, and yield will decrease significantly.

② Seed selection. Choose newly produced daughter Yanhusuo of the current year that are medium-sized, uniform, flat-round, yellow, without wounds, and without insect holes as seed. If the selected seed is too large, the planting amount will increase. If old mother Yanhusuo is used as seed, its reproductive capacity is weak and yield will be affected. Seed selected according to requirements has many stem buds on the tuber, emerges robustly, and has strong disease resistance.

③ Reasonable close planting. When planting on the bed surface, a row spacing of 2×3 cun or 2.5 cun square is relatively reasonable. Field experiments have shown that the disease incidence rate is directly proportional to planting density. That is, the greater the density, the faster the infection, the higher the disease incidence rate, and the more severe the disease. The comparative test results on infection under different planting densities of 2 cun, 2.5 cun, and 3 cun were: checked on April 11: the infection rate at 2 cun density was more than 55%; the infection rate at 2.5 cun density was 20%; the infection rate at 3 cun density was 10%. Checked on April 25: at 2 cun density, seedling decline was 100%; at 2.5 cun, seedling decline was 70%; at 3 cun, seedling decline was 40%. Early seedling decline affects yield, while delaying seedling decline can increase yield. The reason excessive density causes more disease is mainly that overly dense aboveground stems and leaves affect the microclimate of the Corydalis yanhusuo bed surface, ventilation conditions are poor, light is insufficient, and the relative humidity of the Corydalis yanhusuo bed surface increases, providing a good parasitic and reproductive environment for downy mildew pathogens, so disease occurs early and spreads quickly. However, planting too sparsely is also not acceptable, as too sparse planting reduces yield per unit area.

④ Soil covering. After planting, maintain a reasonable soil covering depth. A depth of 2 cun to 2.5 cun is suitable. In individual cold winter areas, the soil covering depth can be increased to 3 cun. Because the root system of Corydalis yanhusuo is shallow, if the soil covering is thin, the underground stem will have few branches and short stem nodes, and the tubers will overlap, resulting in low yield. If the soil covering is too deep, emergence will be affected and full stands cannot be guaranteed.

⑤ Planting method and sowing amount per mu. First, stretch a rope on the prepared field and tread the beds. On the bed surface, place the seeds at 2.5 cun square. On the placed seeds, thinly broadcast a layer of old wall soil or decomposed finely crushed farmyard manure at 2000~3000 jin per mu, 100 jin of oil cake fertilizer, and 100 jin of phosphate fertilizer. Then use a hoe to lift the soil from the trodden bed ditches onto the bed surface, which is the soil covering, making the bed surface arched. The sowing amount per mu is generally about 120-140 jin, varying with seed size.