The Latest Rehmannia Planting Techniques and Methods Tutorial

Rehmannia, also known as Shengdi (raw rehmannia) and Shudi (prepared rehmannia), belongs to the Scrophulariaceae family, genus Rehmannia. Its rhizome is used medicinally and has effects such as strengthening the heart, diuresis, analgesia, lowering blood sugar, and protecting the liver. It can be cultivated throughout the country. The main techniques and key production measures for high-yield Rehmannia cultivation are as follows.

Site Selection and Land Preparation

It is advisable to choose sandy loam soil with deep soil layers, fertility, and good drainage. In the previous winter or early spring, plow the soil deeper than 25 cm, and at the same time apply 2000-3000 kg of decomposed compost and 25 kg of superphosphate per mu as base fertilizer. Then, level and harrow the soil finely to make beds, generally 1.3 m wide. It is particularly important to note that Rehmannia should not be grown continuously on the same land, which is also a key measure to note in site selection.

Seed Selection and Planting

Generally, Rehmannia is cultivated using rhizomes as propagation material, called 'planting stock' in production. The 'planting stock' of Rehmannia generally uses the 'reverse-planted' 'planting stock' cultivated in July-August of the previous year, because when the 'reverse-planted' 'planting stock' is used as seed, the Rehmannia yield is high, the quality is good, and it can prevent variety degeneration. Before planting, remove the head and tail of the 'planting stock' and take the middle section. Then cut it into small sections 3-6 cm long, each section retaining two to three bud eyes, 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. On the prepared bed surface, dig small holes 3-5 cm deep, place 1-2 sections of 'planting stock' 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 stock'. Note that when selecting seeds, try to use 'reverse-planted' 'planting stock' and avoid using small commercial stock; at the same time, the 'old mother tubers' should be removed from the 'planting stock'. That is, the planting stock planted in the first ten days of the month.

Field Management

1. Thin and replant seedlings in time. When the seedlings are 10-12 cm tall, begin thinning, leaving 1 strong seedling per hole. If there are missing plants, replant promptly on cloudy days, and when replanting, lift the seedlings with soil, so the survival rate is higher;

2. Cultivation and weeding. The rhizome of Rehmannia enters the soil relatively shallowly, so cultivation should be shallow to avoid damaging the roots. Weeds around the seedlings should be pulled out by hand. 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 it should be watered frequently. In the later stage, which is the underground rhizome enlargement period, water should be saved. In the rainy season, drainage should be done in time 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 more nutrients and should be removed in time.

Prevention of Pests and Diseases

The main diseases of Rehmannia include leaf spot, ring rot, and fusarium wilt. These diseases generally begin to occur in early May and become severe in June-July, so timely prevention and control should be noted. Pests include red spiders, cutworms, and white grubs. These are controlled by conventional methods. When choosing pesticides, avoid using highly toxic pesticides.

Harvesting and Processing

Spring-planted Rehmannia should be dug up in time when the aboveground stems and leaves wither around November of the same year. When digging, open a 35 cm deep trench at one end of the bed and carefully remove the rhizomes in sequence. For processing, use a special roasting oven to process the Rehmannia into Shudi (prepared rehmannia), which then becomes a commercial product.