Rheum, a name in traditional Chinese medicine. It refers to the dried roots and rhizomes of plants in the genus Rheum of the Polygonaceae family, including Rheum palmatum L. (palmate rhubarb), Rheum tanguticum Maxim. ex Balf. (Tangut rhubarb), or Rheum officinale Baill. (medicinal rhubarb). It has the therapeutic effects of promoting bowel movements to eliminate stagnation, clearing heat and purging fire, cooling the blood and detoxifying, removing blood stasis and regulating menstruation, and draining dampness to relieve jaundice.It is primarily used to treat constipation caused by excess heat and food stagnation; vomiting of blood and epistaxis due to blood heat; red eyes and swollen throat; boils, abscesses, and carbuncles; intestinal abscesses and abdominal pain; amenorrhea due to blood stasis; postpartum blood stasis obstruction; trauma; damp-heat dysentery; jaundice with dark urine; dysuria; and edema. Externally, it is used to treat burns and scalds.
Rhubarb
Rheum, a name in traditional Chinese medicine. It refers to the dried roots and rhizomes of plants in the genus Rheum of the Polygonaceae family, including Rheum palmatum L. (palmate rhubarb), Rheum tanguticum Maxim. ex Balf. (Tangut rhubarb), or Rheum officinale Baill. (medicinal rhubarb). It has the therapeutic effects of promoting bowel movements to eliminate stagnation, clearing heat and purging fire, cooling the blood and detoxifying, removing blood stasis and regulating menstruation, and draining dampness to relieve jaundice.It is primarily used to treat constipation caused by excess heat and food stagnation; vomiting of blood and epistaxis due to blood heat; red eyes and swollen throat; boils, abscesses, and carbuncles; intestinal abscesses and abdominal pain; amenorrhea due to blood stasis; postpartum blood stasis obstruction; trauma; damp-heat dysentery; jaundice with dark urine; dysuria; and edema. Externally, it is used to treat burns and scalds.
Chinese Name : 大黄
Latin Name : Rhei Radix et Rhizoma
Aliases : General, Huangliang, Huoshen, Furu, Shu Da Huang, Jinwen Da Huang, Niusheng Da Huang, Jinwen, Shengjun, Chuanjun
Authentic Producing Area : Gansu, Qinghai, Sichuan
Nature, Flavor & Meridian Tropism : Bitter in taste, cold in nature; enters the Spleen, Stomach, Large Intestine, Liver, and Pericardium meridians
Benefits & Efficacy
Benefits
Purges to eliminate accumulations, clears heat and reduces fire, cools the blood and detoxifies, removes blood stasis and unblocks the meridians, and drains dampness to relieve jaundice.
Indications
Constipation due to real heat and food stagnation; blood heat causing vomiting of blood or epistaxis; red eyes and swollen throat; boils, abscesses, and carbuncles; intestinal abscesses with abdominal pain; menstrual cessation due to blood stasis; postpartum blood stasis obstruction; trauma from falls or blows; damp-heat dysentery; jaundice with red urine; dysuria; edema; externally used to treat burns and scalds.
Usage and Dosage
1. Internal Use: Decoct 3–12 g; for purgation and bowel movement relief, add the herb toward the end of decoction and do not boil for too long; alternatively, steep in boiling water and drink the infusion; take 0.5–2 g as a powder; or incorporate into pills or powders. 2. External Use: Use an appropriate amount; grind into a powder and apply as a poultice, or decoct in water for washing or topical application. The decoction may also be used for enemas.
Precautions
1. Rhubarb is a potent purgative that can easily deplete vital energy; it should not be used indiscriminately unless a pattern of excess is present. 2. If you need to use other medications concurrently while taking rhubarb, consult a doctor or pharmacist first. Do not self-medicate to avoid drug interactions that may reduce efficacy or increase the risk of adverse reactions.
Chemical Constituents
It primarily contains anthraquinone components (aloe-emodin, emodin acid, emodin, emodin methyl ether, emodin phenol, etc.), conjugated anthraquinone components (emodin methyl ether-8-glucoside,aloe-emodin-8-glucoside, etc.), and dianthrones (sennosides A, B, C, and D), as well as essential oils.
Pharmacological Actions
This product has laxative, anti-ulcer, intestinal mucosal barrier-protective, antimicrobial, anti-acute pancreatitis, nephroprotective, hepatoprotective and cholagogue, and anti-fibrotic effects.
Relevant Discussions
1. *Shennong’s Classic of Materia Medica*: “It expels stagnant blood, treats blood stasis with alternating chills and fever, breaks up masses and accumulations, eliminates retained fluid and undigested food, cleanses the intestines and stomach, removes the old to make way for the new, promotes the passage of water and food, regulates the middle burner to aid digestion, and harmonizes the five viscera.”
2. *Treatise on the Nature of Medicinal Substances*: “It treats fever and chills, aids digestion, purifies the five viscera, regulates the menstrual cycle in women, alleviates edema, dispels phlegm and stagnation, resolves cold and heat accumulations and undigested food, promotes the function of the small and large intestines, alleviates heat-toxin-induced swelling, treats childhood febrile illnesses and intermittent fevers, relieves restlessness and fever, eliminates pus, and expels retained blood.”
3. *Compendium of Materia Medica*: “Treats bloody or white diarrhea, tenesmus and abdominal pain, dribbling urination, real heat and dry constipation, tidal fever and delirium, jaundice, and various inflammatory sores.”
4. *Collected Commentaries on the Classic of Materia Medica*: “Scutellaria baicalensis serves as its adjuvant.”
Applications
Clinical Applications
1. For treating Yangming腑实 syndrome, it is often combined with芒硝, 厚朴, and 枳实 to enhance the purgative effect and eliminate accumulations, forming an urgent purgative formula, such as 大承气汤 (from *Treatise on Cold Damage*); if the dose of Rheum palmatum is relatively light and it is used with intestinal-moistening herbs such as Sesamum indicum, Prunus armeniaca, and honey, the laxative effect is milder, as seen in the Sesamum indicum Pill (Treatise on Cold Damage).
2. For treating internal heat accumulation with deficiency of vital energy, it should be combined with tonifying herbs to simultaneously attack the pathogen and tonify the body, addressing both the symptoms and the root cause.To treat heat accumulation with deficiency of qi and blood, it should be combined with herbs such as ginseng and angelica root, as in the Huanglong Decoction (*Treatise on Cold Damage*); to treat heat accumulation with fluid depletion, it should be combined with herbs such as ophiopogon, raw rehmannia, and scrophularia, as in the Zengye Chengqi Decoction (*Treatise on Warm Diseases*); to treat spleen yang deficiency and cold-induced constipation, it must be combined with herbs such as aconite and dried ginger, as in the Wenspi Decoction (*Essential Prescriptions Worth a Thousand Gold for Emergency Use*).
3. To treat hematemesis, epistaxis, and hemoptysis caused by uncontrolled blood heat, it is often used in combination with Coptis and Scutellaria, as in Xiexin Decoction (*Jin Gui Yao Lue*).
4. For upper gastrointestinal bleeding, modern clinical practice has shown that using rhubarb powder alone yields good therapeutic results.
5. To treat symptoms such as red eyes, sore throat, and swollen, painful gums caused by fire pathogen rising upward, it is used in combination with herbs such as Scutellaria baicalensis and Gardenia jasminoides, as in the Liangge Powder (from *Formulas of the Bureau of Harmonious Preparations*).
6. To treat abscesses, boils, and carbuncles caused by heat toxins, it is often used in combination with Lonicera japonica, Taraxacum officinale, and Forsythia suspensa.
7. To treat intestinal abscesses and abdominal pain, it can be used in combination with Moutan Bark, Peach Kernel, and Mirabilite, as in the Rhubarb and Moutan Decoction (from *Jin Gui Yao Lue*).
8. To treat mastitis, it can be used in the Jin Huang Powder (from *Women’s Effective Formulas*), which is prepared by grinding it into a powder with Licorice Root and boiling it with wine to form a paste.
9. To treat oral ulcers and erosions, it is often ground into a powder in equal parts with calcined alum and applied to the affected area (*Taiping Shenghui Fang*).
10. To treat burns and scalds, the powder may be used alone or combined with *Di Yu* powder, mixed with sesame oil and applied to the affected area.
11. To treat postpartum abdominal pain due to blood stasis and persistent lochia, it is often used in combination with peach kernels and earth beetles, as in the Decoction for Expelling Stagnant Blood (Jin Gui Yao Lue).
12. To treat amenorrhea caused by blood stasis in women, it can be combined with peach kernels and cinnamon twigs, as in the Peach Kernel Chengqi Decoction (Shanghan Lun).
13. To treat trauma-induced injuries, blood stasis, and swelling and pain, it is often combined with Angelica sinensis, Safflower, and Manis pentadactyla, as in the Fuyuan Huoxue Decoction (*Medical Inventions*).
14. To treat dysentery caused by damp-heat stagnation in the intestines, using Rheum palmatum alone is effective (*Collection of Disease Mechanisms, Appropriate Treatments, and Life-Preserving Methods from the *Su Wen*), or it may be combined with Coptis, Scutellaria, and White Peony.
15. For treating damp-heat jaundice, it is often combined with Yinchen and Zhizi, as in the Yinchenhao Decoction (*Treatise on Cold Damage*); for treating damp-heat dysuria, it is often combined with Mutong, Cheqianzi, and Zhizi, as in the Bazheng Powder (*Formulas of the Bureau of Harmonious Preparations*).
16. For treating chronic phlegm obstruction, shortness of breath preventing the patient from lying flat, mania, madness, and epilepsy, as well as severe constipation, such as the Longshi Guntan Pills (from *The Treatise on the Master of Nourishing Life*).
Related Compatibility
1. Rhubarb combined with Artemisia capillaris and Gardenia: Rhubarb clears heat, expels stasis, and promotes bowel movements, guiding stasis and heat to be eliminated through the stool; Artemisia capillaris is the primary herb for treating jaundice, excelling at clearing heat, draining dampness, and alleviating jaundice; Gardenia excels at clearing and draining damp-heat from the liver and gallbladder.When these three herbs are combined, they drain dampness and clear heat, promoting the smooth passage of both urine and stool. By resolving the condition from both the front and back, allowing damp-heat to dissipate and stasis-heat to be expelled, jaundice will naturally subside. This formula is suitable for damp-heat jaundice.
2. Rhubarb combined with Aconite: Rhubarb acts as a purgative to relieve constipation and flush out internal stagnation and accumulation; Aconite, with its pungent and hot nature, warms the interior to dispel cold and alleviates pain in the abdomen and flanks caused by cold stagnation. When combined, they use purgation to eliminate stagnation and warm the interior to dispel cold-induced stagnation, making them highly effective for treating cold-induced stagnation, constipation, and abdominal pain.
3. Rhubarb combined with Zhi Shi: Rhubarb excels at purging, unblocking stagnation, and eliminating tangible accumulations, while Zhi Shi excels at regulating qi, relieving fullness, and dissipating intangible stagnation. When used in combination, they complement each other, producing a potent and vigorous purgative effect that clears the intestines. This formula is used for gastrointestinal stagnation and severe constipation.
4. Rhubarb combined with charred Sanguisorba: Rhubarb clears heat, cools the blood, and detoxifies, while charred Sanguisorba cools the blood, stops bleeding, and promotes wound healing and tissue regeneration. When combined, these two herbs work together to cool the blood, detoxify, and promote wound healing and tissue regeneration; ground into a fine powder, they are applied topically to treat burns and scalds.
5. Rhubarb combined with Raw Rehmannia Root: Rhubarb can both act as a purgative to relieve constipation and clear heat, cool the blood, and stop bleeding, while also removing blood stasis to ensure that bleeding is stopped without leaving residual stasis; Raw Rehmannia Root can both nourish yin, generate body fluids, moisten the intestines, and relieve constipation, as well as clear heat, cool the blood, and stop bleeding. When combined, these two herbs achieve the effects of relieving constipation and stopping bleeding, and are used for constipation due to intestinal dryness or bleeding caused by blood heat.
6. Rhubarb combined with Peony Bark: Rhubarb clears heat, detoxifies, removes blood stasis, and promotes bowel movements; Peony Bark activates blood circulation, removes blood stasis, and relieves pain. When used together, they clear heat, detoxify, remove blood stasis, and relieve pain, and are used in the early stages of intestinal abscess with abdominal pain.
Medicinal Identification
Raw Rheum, Wine-Processed Rheum, Cooked Rheum, and Charred Rheum: These four are different processed forms of Rheum. Due to variations in processing methods, their therapeutic effects differ in emphasis. Raw Rheum has a strong purgative effect; therefore, it is suitable for purgative treatments. When used in decoctions, it should be added last or steeped in boiling water before consumption; prolonged boiling weakens its purgative potency.Wine-processed rhubarb has a milder laxative effect and is particularly effective at clearing heat toxins from the blood in the upper jiao; it is suitable for treating red eyes, swollen throat, and swollen, painful gums. Cooked rhubarb has a gentle laxative effect and is used to clear fire and detoxify in cases of fire-toxin sores and ulcers. Charred rhubarb cools the blood, resolves stasis, and stops bleeding; it is often used for bleeding syndromes caused by blood heat with stasis.
Related Medicines
Qingxie Pills, Qingning Pills, Uremic Clear Granules, Rhubarb Stomach-Clearing Pills, Gastrointestinal Recovery Ointment.
Related Prescriptions
Da Chengqi Decoction (*Treatise on Cold Damage*), Rhubarb and Peony Decoction (*Essentials of the Golden Cabinet*), Warm Spleen Decoction (*Thousand Gold Prescriptions*), Peach Kernel Chengqi Decoction (*Treatise on Cold Damage*), Rhubarb and Silkworm Pills (*Essentials of the Golden Cabinet*).
Notes
Patients requiring treatment with Chinese herbal medicine should first consult a licensed Traditional Chinese Medicine (TCM) hospital, where a TCM practitioner will conduct a professional pattern differentiation and prescribe an herbal formula.
Processing & Preparation
Harvesting & Processing
Harvest in late autumn when the stems and leaves have withered, or before sprouting the following spring. Remove fine roots, scrape off the outer skin, cut into segments or slices, string them together with twine for drying, or dry them directly.
Processing Methods
1. Rheum: Take the raw material, remove impurities, sort by size, wash thoroughly, moisten thoroughly, cut into thick slices or small cubes, and air-dry or dry at a low temperature.
2. Wine-Processed Rheum: Take Rheum slices, mix thoroughly with yellow wine, let stand until thoroughly moistened, place in a pot, heat over low heat, stir-fry until dry, then remove and let cool. Use 10 kg of yellow wine for every 100 kg of Rheum slices.
3. Wine-Stewed Rhubarb: Take rhubarb slices or cubes, mix thoroughly with yellow wine, let stand briefly, then place in a medicinal stew pot or suitable container. Stew or steam until both the interior and exterior turn black. Remove and dry. Use 30 kg of yellow wine for every 100 kg of rhubarb slices or cubes.
4. Charred Rhubarb: Place rhubarb slices in a pot and heat over high heat, stir-frying until the surface is charred black and the interior is charred brown. Sprinkle with a small amount of water to extinguish all embers, then remove and allow to cool completely.
5. Vinegar-Processed Rhubarb: Take rhubarb slices, mix thoroughly with rice vinegar, and let stand until thoroughly moistened. Place in a pot, heat over low heat, stir-fry until dry, then remove and let cool. For every 100 kg of rhubarb slices, use 15 kg of rice vinegar.
6. Honey-Processed Rhubarb: First, place refined honey in a pot and heat until boiling. Add the rhubarb slices and stir-fry over low heat until they no longer stick to your hands, then remove and let cool.Use 18 kg of refined honey per 100 kg of rhubarb slices.
7. Processed Rhubarb (with Plantain Herb and Platycladus Leaf): First, sort the rhubarb to remove impurities, soak it in clean water for about 6–8 hours, then remove it. Once the soaking water has settled and been filtered to remove sediment and impurities, pour it into a pot.For every 100 kg of raw dried rhubarb, add the auxiliary materials (10 kg of fresh plantain herb and 10 kg of fresh side-cypress leaves). Layer them with the rhubarb in the pot and boil over high heat for 4–6 hours. When the liquid is nearly evaporated, add 10 kg of white liquor, mix well, and then simmer over low heat for about 10–20 minutes until all moisture is absorbed. Remove from the pot.Remove the plantain herb and Chinese arborvitae leaves. When the rhubarb is about 50% dry, cut it into small 7–10 mm cubes with a knife, then sun-dry or oven-dry it. Turn the pieces frequently during sun-drying to prevent mold.
Storage Methods
Store in dry containers. Alcohol-processed rhubarb, fermented rhubarb, vinegar-processed rhubarb, honey-processed rhubarb, and prepared rhubarb should be kept in a cool, dry place to prevent insect infestation. Charred rhubarb emits heat and must be protected from reignition.
Crude Drug Identification
Identification
1. Cross-section of this product: The root cork layer and subcork layer have mostly been removed. The phloem sieve tube groups are distinct; the parenchyma tissue is well-developed. The cambium forms a ring. The xylem rays are relatively dense, 2–4 cells wide, and contain brown substances; the vessels are non-lignified, often clustered in groups of one to several, and arranged sparsely.Parenchymatous cells contain calcium oxalate cluster crystals and numerous starch grains. The rootstock pith is broad and commonly contains mucilage cavities filled with reddish-brown material; heteromorphic vascular bundles are scattered; the cambium forms a ring; the xylem is located outside the cambium, the phloem is located inside the cambium, and the rays radiate in a star-like pattern.The powder is yellowish-brown. Calcium oxalate cluster crystals range in diameter from 20 to 160 μm, with some reaching 190 μm. Vessels with marginal pores, reticulate vessels, spiral vessels, and annular vessels are non-lignified. Starch grains are very numerous; single grains are subglobose or polygonal, 3–45 μm in diameter, with a stellate hilum; compound grains consist of 2–8 subgrains.
2. Take a small amount of the powdered sample and perform micro-sublimation; rhomboidal needles or feather-like crystals are visible.
3. Take 0.1 g of the powdered sample, add 20 mL of methanol, and soak for 1 hour;filter; take 5 mL of the filtrate and evaporate to dryness; dissolve the residue in 10 mL of water; add 1 mL of hydrochloric acid; reflux for 30 minutes; cool immediately; extract with ether in two shaker extractions of 20 mL each; combine the ether solutions and evaporate to dryness; dissolve the residue in 1 mL of chloroform to prepare the test solution.Separately, take 0.1 g of rhubarb reference material and prepare a reference material solution using the same method.Next, take a reference standard of rheinic acid and dissolve it in methanol to prepare a solution containing 1 mg per mL; use this as the reference standard solution. Perform the test according to the Thin-Layer Chromatography method (General Chapter 0502). Pipette 4 μL of each of the three solutions mentioned above and apply them separately onto the same silica gel H thin-layer plate using sodium carboxymethyl cellulose as the binder. Develop the plate using the upper layer of a mobile phase consisting of petroleum ether (30–60 °C)-ethyl formate-formic acid (15:5:1) as the developing agent, develop the plates, remove them, allow them to air-dry, and examine them under ultraviolet light (365 nm).In the chromatogram of the test sample, five orange-yellow fluorescent main spots identical to those in the chromatogram of the reference herbal material appear at the corresponding positions; at the positions corresponding to the chromatogram of the reference standard, identical orange-yellow fluorescent spots appear, which turn red after exposure to ammonia vapor.
Properties of Crude Drugs
This product is cylindrical, conical, ovoid, or irregularly lump-shaped, 3–17 cm long and 3–10 cm in diameter. The surface, where the outer bark has been completely removed, is yellowish-brown to reddish-brown; some specimens show scattered off-white reticulate patterns and star-shaped dots (atypical vascular bundles). The residual outer bark is brownish-black, often with lenticels and coarse wrinkles.The texture is firm, though the center may be slightly soft in some specimens. The cross-section is pale reddish-brown or yellowish-brown and appears granular; the storage portion of the rhizome is broad, with star-shaped dots arranged in rings or scattered throughout; the woody portion of the root is well-developed, featuring radial striations, a distinct cambium ring, and no star-shaped dots. It has a fresh, fragrant aroma; the taste is bitter with a slight astringency; when chewed, it sticks to the teeth and has a gritty sensation.
Properties of Processed Slices
1. Rheum: Irregular thick slices or small cubes; the surface is reddish-brown or yellowish-brown, with clearly visible star-shaped spots. It has a fragrant aroma and a bitter, slightly astringent taste.
2. Wine-processed Rheum: Resembles Rheum slices; the surface is dark brown, occasionally with scorched spots, and has a slight wine aroma.
3. Fermented Wine-processed Rheum: Resembles Rheum slices; the surface is blackish-brown, with a faint wine aroma.
4. Charred Rheum: The surface is charred black, the interior is brown; it is light and brittle, with a charred aroma; the taste is slightly bitter and astringent.
5. Vinegar-processed Rheum: Resembles Rheum slices; has a slight vinegar odor.
6. Honey-processed Rheum: Resembles Rheum slices; has a slight fragrance; tastes sweet and bitter.
7. Processed Rheum: Resembles Rheum chunks; has a slight fresh fragrance; tastes slightly bitter and astringent.
Botanical Information
Botanical Classification
Rheum palmatum, Rheum tanguticum, or medicinal rhubarb, belonging to the genus Rheum in the Polygonaceae family.
Morphological Characteristics
1. Palmate-leaved Rheum: A tall, perennial herb. The rhizome is robust. The stem is erect, about 2 m tall, hollow, smooth, and glabrous.Basal leaves are large, with stout, fleshy petioles approximately as long as the leaf blade; leaf blades are broadly cordate or nearly circular, up to 40 cm in diameter, deeply palmately lobed into 3–7 segments, with each segment often further pinnately divided; the upper surface is sparsely covered with papillate projections, while the lower surface is pubescent; cauline leaves are smaller, with short petioles; stipule sheaths are tubular and densely covered with short soft hairs.The inflorescence is a large panicle, terminal; flower pedicels are slender, with joints in the middle and lower parts. Flowers are purplish red or reddish-purple; there are 6 perianth segments, approximately 1.5 mm long, arranged in two whorls; 9 stamens; and 3 styles. The achenes are 3-angled, with wings along the ridges, slightly depressed at the apex, nearly heart-shaped at the base, and dark brown.Flowering period: June–July; fruiting period: July–August.
2. Tangut Rhubarb: This species is very similar to Palm-leaved Rhubarb, with the main distinction being that the leaves are deeply lobed, with lobes often triangular-lanceolate or narrowly linear in shape and long and narrow. The inflorescence branches are densely clustered, erect, and closely appressed to the stem.
3. Medicinal Rhubarb: The main differences between this species and the previous two are that the basal leaves are shallowly 5-lobed, with the lobes broadly toothed or broadly triangular; the stipule sheaths are membranous, relatively transparent, and covered with short hairs. The flowers are relatively large and pale yellow-green; the flower buds are oval; the fruit branches are spreading; and the margins of the winged fruits are opaque.
Distribution Area
1. Palm-leaved Rhubarb: Distributed in Shaanxi, southeastern Gansu, Qinghai, western Sichuan, northwestern Yunnan, and eastern Tibet. 2. Tangut Rhubarb: Distributed in Gansu, Qinghai, Sichuan, and northeastern Tibet. 3. Medicinal Rhubarb: Distributed in southern Shaanxi, western Henan, western Hubei, Sichuan, Guizhou, Yunnan, and other areas.
Growth Habits
It prefers a cool climate, is cold-tolerant, and cannot tolerate high temperatures. It grows wild in the high mountains of northwestern and southwestern China at altitudes of around 2,000 m; cultivated varieties are mostly grown in areas above 1,400 m. The minimum winter temperature should be below -10°C, the summer temperature should not exceed 30°C, the frost-free period should be 150–180 days, and annual precipitation should be around 500–1,000 mm.It is quite particular about soil conditions; generally, deep, humus-rich, well-drained loam or sandy loam is best. It is not suitable for planting in heavy, acidic soils or low-lying, waterlogged areas. It does not tolerate continuous cropping; a 4–5-year rotation is required before replanting.
Propagation Methods
Propagation is by seed, though it can also be done using root buds (buds on the mother plant’s rhizome).
Cultivation Techniques
1. Seed Propagation: Since rhubarb varieties are prone to hybridization and variation, select three-year-old plants of relatively pure varieties as seed stock. In mid- to late July, when most seeds have turned dark brown, cut the plants back along with the stems, dry them in the shade, and thresh the seeds for later use. Two methods are available: seedling transplantation and direct seeding. There are spring and fall sowing options, with fall sowing generally preferred. For seedling propagation, seeds may be sown in rows or broadcast.For row sowing, dig transverse furrows spaced 25–30 cm apart, with a sowing width of 10 cm and a depth of 3–5 cm; use 30–75 kg of seed per hectare. For broadcast sowing, scatter the seeds evenly over the bed surface, cover lightly with fine soil, and cover with straw. Use 75–105 kg of seed per hectare. After germination, remove the straw cover on a cloudy day or in the afternoon on a sunny day.Once the seedlings have emerged uniformly, weed and water promptly. If the seedlings are too dense, thin them out during the first weeding. Apply diluted human or animal manure 2–3 times during the seedling stage. After the plants have overwintered in early winter, cover them with soil, straw, or fallen leaves; remove the covering when new growth appears the following year. Spring-sown plants should be transplanted in March–April of the following year, while fall-sown plants should be transplanted in September–October of the following year.Select seedlings with roots as thick as a middle finger; trim off the lateral roots and the slender sections of the taproot. Dig holes with a row spacing of 70 cm and a plant spacing of 50 cm, each about 30 cm deep, planting one seedling per hole. For spring transplanting, cover the soil lightly so that the seedling leaves remain above ground to promote growth; for fall transplanting, cover the soil thickly, ensuring it is 5–7 cm above the bud point to prevent winter frost damage.For direct seeding, sow seeds in holes spaced 60–80 cm apart in rows and 50–70 cm apart between plants. The holes should be about 3 cm deep, with 5–6 seeds sown per hole and covered with about 2 cm of soil. Use 22.5–30 kg of seed per hectare. Seedling management is the same as for the seedling transplanting method. Thin the seedlings 1–2 times, and finalize the spacing when the seedlings reach 10–15 cm in height, leaving one plant per hole.
2. Propagation by Offshoots: When harvesting rhubarb, remove healthy, large offshoots that have sprouted from the mother plant’s rhizome. Dig holes with a row and plant spacing of 55 cm × 55 cm. Place one offshoot per hole with the bud eye facing upward, cover with 6–7 cm of soil, and firm the soil. Apply wood ash to the cut surfaces during planting to prevent rot.
Pest and Disease Control
1. Diseases: Root rot, ring spot, scab, anthracnose, downy mildew, etc. Implement integrated pest management by practicing crop rotation; ensure good soil drainage; promptly remove and burn diseased plants, and disinfect the soil around the affected area with lime;Remove dead branches, fallen leaves, and weeds to eliminate overwintering sources of disease; spray or water with a 1:1:120 Bordeaux mixture before or during the onset of disease.
2. Pests: Japanese beetles and aphids can be controlled with chemical pesticides. Japanese beetle infestations can also be managed by hand-picking adults in the morning or using lights to attract and kill them at night.