How to Grow Rehmannia? A Complete Guide to Key Cultivation Techniques

        Rehmannia, also known as Shengdi (raw rehmannia root) and Shudi (prepared rehmannia root), is grown for its rhizome, which is used medicinally and has effects such as strengthening the heart, promoting diuresis, relieving pain, lowering blood sugar and protecting the liver. It can be cultivated in all parts of the country. How do you grow rehmannia? The key points of rehmannia cultivation methods are described below:        1. Site selection and land preparation. Choose a sandy loam soil with deep, fertile soil and good drainage. In the winter of the previous year or in early spring, plow the soil to a depth of more than 25 cm, and at the same time apply 2000-3000 kg of decomposed compost and 25 kg of superphosphate per mu as a base fertilizer. Then level the ground, rake it fine and make beds, generally 1.3 m wide. Pay special attention to the fact that rehmannia should not be planted in continuous cropping, and this is also a key measure to note when selecting a site.        2. Seed selection and planting. Generally, rehmannia is cultivated using rhizomes as propagation material, known in production as 'planting sets'. For rehmannia 'planting sets', the 'inverted planting' 'planting sets' cultivated in July-August of the previous year are generally selected, because when 'inverted planting' 'planting sets' are used as seed material, the rehmannia yield is high, the quality is good, and variety degeneration can be prevented. Before planting, remove the head and tail of the 'planting set' and take the middle section. Then cut it into small sections 3-6 cm long, each section retaining two to three buds, dip the cut ends in plant ash, let them dry slightly and then plant. The general planting density is 30-40 cm between rows and 25-30 cm between plants. Dig small holes 3-5 cm deep on the prepared bed surface, place 1-2 sections of 'planting set' horizontally in each hole, cover with a handful of burnt soil ash mixed with manure water, and then cover with fine soil level with the bed. Each mu requires 40-60 kg of 'planting sets'. When selecting seed material, try to use 'inverted planting' 'planting sets' as much as possible, avoid using small commercial ones, and the 'planting sets' should have the 'old mother root' removed. That is, the seed sets planted in the first ten days of the month. Rehmannia pictures        3. Field management. (1) Timely thinning and replanting. When the seedlings are 10-12 cm tall, begin thinning, leaving 1 strong seedling per hole. Where there are missing plants, replant promptly on cloudy days, and when replanting, lift the seedlings with soil, as this gives a higher survival rate; (2) Cultivation and weeding. The rhizome of rehmannia is relatively shallow in the soil, so cultivation should be shallow to avoid damaging the roots. Weeds around the seedlings should be pulled out by hand, and after the plants close the rows, stop cultivation; (3) Topdressing. Rehmannia likes fertilizer. In addition to applying sufficient base fertilizer, after thinning apply 100 kg of superphosphate and 30 kg of decomposed cake fertilizer per mu to promote rhizome development and enlargement. When the rows close, spread burnt soil ash once between the rows to promote robust plant growth; (4) Irrigation. Rehmannia needs a large amount of water in the early stage, so water frequently. In the later stage, which is the period of underground rhizome enlargement, water should be used sparingly. In the rainy season, drain promptly to prevent root rot; (5) Remove creeping surface roots. In addition to the main root, rehmannia can also grow slender underground stems along the soil surface, called creeping surface roots. These creeping surface roots consume a considerable amount of nutrients and should be removed promptly.        4. Pay attention to preventing pests and diseases. The main diseases of rehmannia are leaf spot disease, ring rot, and fusarium wilt. These diseases generally begin to occur in early May and become severe in June-July, so timely control should be noted. Pests include red spiders, cutworms, and white grubs. These are controlled by conventional methods, and when choosing pesticides, avoid using highly toxic pesticides.        5. Harvesting and processing. Rehmannia planted in spring should be dug promptly around November of the same year when the aboveground stems and leaves turn yellow and withered. When digging, open a 35 cm deep trench at one end of the bed and carefully remove the rhizomes in sequence. For processing rehmannia, use a special roasting oven to process it into Shudi, which then becomes a commercial product.