Planting technique
First, the main points of cultivation
1. Variety selection: spearmint is divided into two varieties: big leaf and small leaf. Generally, spearmint with big leaf is selected, which has strong adaptability, fast growth, high oil content in stems and good quality.
2. Sowing method: Because of the great variation of seed reproduction, rhizome reproduction and branch reproduction are generally used in production. Rootstock propagation method was adopted locally. In early April, the underground roots of spearmint were dug out, and fresh roots without diseases and pests were selected, cut into 5-8 cm root segments, placed in the already-opened sowing ditch according to the width and width of (60 cm+40 cm) × 10 cm, and then covered with soil. The amount of roots to be planted in the field is 667 square meters (1 mu) and 80 ~100 kg.
3. Intertillage and weeding: The temperature at seedling stage is low, so it is necessary to loosen the soil and weed1~ 2 times before closing the row (seedling height15 ~ 20cm). When loosening the soil, it should be shallow near the plants, and deeper between rows. After the rain, the soil should be loosened in time. Weeds should also be removed manually 1 time before harvesting, so as to avoid mixing during harvesting and affect the quality of essential oil.
4. Fertilization: topdressing1~ 2 times in the whole growth period. When the plant height is 10 cm, seedling fertilizer can be applied, and 5 ~ 8 kg of urea can be applied to 667 square meters; The second fertilization can be based on the growth situation, and 3 kg of phosphate fertilizer and 5 kg of urea can be applied every 667 square meters in the first half of June, so as to promote the healthy stalks of spearmint to increase oil and increase yield.
Second, the harvest time
Spearmint is harvested twice a year, from May to August. The 1 time is in the late July, which is the first flowering season. When 60% of the plants in the field have 2 or 3 inflorescences, the oil content in the stems and leaves of the plants is the highest, which is the best harvest time. When harvesting, you should choose the morning with continuous sunny days. Harvesting in rainy and windy weather with weak sunshine has a great influence on yield. After harvesting, it can be distilled when it is spread on the ground for 70 thousand.
Third, home cultivation techniques
Spearmint, like mint, is one of the important natural perfume plants. There are two kinds of spearmint cultivated in China: "big leaf" and "small leaf". The former has wide adaptability, strong growth potential and high crude oil output, with an annual yield of about 7 kilograms per mu, but the aroma of crude oil is poor; The latter has poor adaptability, easy lodging, and serious diseases. The crude oil output is low, with an annual yield of about 5 kilograms per mu, but the crude oil has good aroma and good quality.
Spearmint likes warm and humid, and its adaptability to environmental conditions is stronger than that of mint. It can be planted in most parts of China, and it is usually sown during the winter solstice and heavy snow. When the temperature is about 5℃ in early spring, the seeds planted in the soil can germinate and emerge. In production, underground stems are generally used as propagation materials, and some plants of runners and aboveground parts are cut into small sections with 2-3 nodes as propagation materials. The specific cultivation requirements are:
1, reasonable close planting. The branching ability of spearmint is very strong, the basic seedling of the first knife should be controlled at around1-25,000, and the second knife should be controlled at12-150,000. The basic seedlings of the first knife are too dense or too thin. We should move the density and replenish the density in time. Densification and thinning can only be carried out when the temperature is stable above 10℃, otherwise the survival rate will be reduced. It is not advisable to plan the roots after harvesting with the first knife. It is best to remove the mud from the drainage ditch and cover it on the field after harvesting with the same mud surface, otherwise it will be difficult for the second knife to fully plant the seedlings.
2. Strictly remove impurities. Spearmint is easily degraded and mixed, and impurity removal should be carried out when the true wild spearmint can be identified.
3. Rational fertilization. Fertilization should be based on the density and planting method in principle. In fields with a certain amount of base fertilizer or fertile soil, seedling fertilizer should be applied in general, branch fertilizer should be applied again, and brake fertilizer should be applied skillfully. For fields with density above1.5000, seedling fertilizer and branch fertilizer should be lightly applied, and brake fertilizer should be heavily applied. The intercropping field should adopt the fertilization method of light at both ends and heavy in the middle, that is, after the intercropping crop is harvested, it should be fertilized by heavy water once to promote the growth of branches and leaves. The growth period of spearmint is short, and the temperature is from high to low during the whole growth period. Therefore, we should make use of the climatic conditions conducive to its growth at the seedling stage to promote the early emergence of strong seedlings. On the basis of early seedlings, it is necessary to make the spearmint "one blow" in the early growth stage. The principle of fertilization is "promoting before controlling" and "one blast and one supplement", that is, more fertilizer should be applied in the seedling stage and the middle and early stage, and less or no fertilizer should be applied in the later stage.
4, timely harvest. According to the factors related to improving crude oil production, the appropriate recovery period is determined. Both the first-cut and the second-cut spearmint have the highest yield from the first flower to the full flower stage; In a day, the harvest yield is usually the highest from 10 to 14 on sunny days; Do not harvest on rainy days and when the wind and dew are still wet. Do not cut when the growth period is uncomfortable, the sun is insufficient, the temperature is not high, the wind and rain are not cut, the dew is not dry, and the ground is wet.