Propagation Methods and Key Cultivation Techniques for Black Cohosh

Black CohoshIt prefers a warm and humid climate. It is cold-hardy; seedlings of the current year can safely overwinter at a low temperature of -25°C. During the seedling stage it fears direct strong sunlight; during the flowering and fruiting stage it needs ample light. It fears waterlogging and cannot tolerate soil drought. It prefers slightly acidic or neutral humus soil, and grows poorly in alkaline or heavy clay soil. Choose a semi-shaded, semi-sunny hillside slope at an altitude of about 1000 m with deep soil layers and rich humus, or level sandy loam ground with good drainage. After choosing the site, remove field debris and deep-plow 30-40 cm. Apply base fertilizer at 1000-2000 kg per mu, break up the clods, rake fine and level, and make beds 20 cm high and 100-130 cm wide. The transplanting site can also be made into large ridges 60-70 cm wide.

Propagation Methods

Seed propagation. Seed harvesting and treatment: because black cohosh has a long flowering period, the seeds mature at varying times; when the fruit ripens the valves split open naturally and the seeds fall with the wind. Therefore, harvest as they ripen; when the fruit begins to turn yellow from green, the skin starts to dry out, and the valves are about to split, cut off the fruit cluster. After sun-drying, the skin splits completely open; remove the skin and impurities, and after the seeds are sun-dried again they can be sown in autumn. If sowing in the following spring, mix the seeds with fine sand at 1:3 for sand storage, water to keep moist, and store outdoors at low temperature. Note that old seeds from the previous year must not be used in cultivation, because after harvest, if stored dry indoors for 2 months, the germination rate is below 10%, and after one year of storage most will not germinate.

Sowing. Both spring and autumn are suitable; in spring it is from late March to mid-April. When sowing, first open furrows along the bed at a row spacing of 20-25 cm, with a furrow depth of 4-5 cm, sow the seeds evenly in drills in the furrows, cover with fine soil 1.5-2 cm, press lightly, and when the soil is dry give one thorough watering with a watering can, then cover the bed surface with a layer of straw to retain moisture. In autumn, sow from mid-October to early November, using the same method as in spring.

For spring sowing, when the temperature is 15-20°C, seedlings emerge in 18-20 days. Remove the straw from the bed surface gradually, keep the seedbed soil moist, and in drought water with a watering can in the morning and evening. Because seedlings fear strong light, shade the upper part of the bed with a simple reed curtain. Transplant after the seedlings have grown for 1 year; the transplanting time is after the aboveground parts wither in autumn or before they green up in spring. In the prepared field, open holes at a plant spacing of 30 cm and row spacing of 45 cm, with a hole depth of 15 cm, plant 1 seedling per hole, and cover with soil to a level 4-5 cm above the terminal bud, then water thoroughly once after planting.

Field management. In dry spring weather, water to maintain moisture. During the growing period, loosen the soil and weed frequently. Two-year-old black cohosh bears less fruit and the seed quality is poor; to avoid affecting rhizome growth, the inflorescence should be cut off at the early bud stage, and in July-August, before the rainy season arrives, hill up the soil appropriately. If drought occurs, water promptly to keep the soil moist and promote seedling growth. During the seedling stage, cultivate and weed frequently, and hoe shallowly to prevent damaging the rhizome. At the same time, in combination with loosening the soil and weeding, apply an appropriate amount of nitrogen fertilizer in June-July according to seedling growth. Two-year-old black cohosh bears less fruit and the seed quality is poor; at the early bud stage the inflorescence can be cut off to favor rhizome growth. Thereafter, cultivate and weed 1-2 times each year. In the rainy season of July-August each year, hill up soil toward the roots appropriately to prevent water accumulation. This is because in the hot, rainy summer season many plants die from root rot.

Pest and disease control. Black cohosh has very few pests and diseases, with only a small number of white grubs, which mainly damage the rhizome, generally occurring in May-June; they can be controlled by drenching the roots with 800-fold 40% dimethoate emulsifiable concentrate. Among diseases, there is gray leaf spot, which damages the leaves and occurs in August-September; it can be prevented by spraying Bordeaux mixture at 1:1:120 before onset, and controlled with 500-fold 65% zineb in the early stage of the disease.

Harvesting and processing. Cultivated black cohosh can be harvested after 4 years of growth, mainly in autumn. When harvesting, choose a sunny day, first cut off the withered branches, stems, and leaves of the aboveground parts, dig out the rhizome, remove the soil, wash clean, and when sun-dried to 80% dry, singe off the fibrous roots with fire, then sun-dry until fully dry, and knock off the outer skin and remaining fibrous roots. It can be packed in gunny bags, about 20 kg per piece, and stored in a dry, ventilated place.