Detailed Guide to Mint Cultivation Methods, Step-by-Step Teaching You How to Grow Mint

[Overview]Aliases: Su mint, mint leaf, mountain mint, etc.

It is the dried aerial part of the Lamiaceae plant mint (Mentha haplocalyxBriq.) used for medicinal purposes. It has effects such as dispersing wind-heat, clearing the head and eyes, and promoting eruption. It mainly treats wind-heat cold, headache with red eyes, sore throat, mouth sores, measles, and other conditions. It can also be used in the spice, food, cosmetics, and other industries.

The medicinal parts of mint are the stems and leaves. After harvesting and drying, it can be used medicinally, or distilled to extract mint oil and menthol, which have aromatic, stomachic, wind-dispelling, diaphoretic, antispasmodic, antipyretic, and analgesic effects. The main components contained in the plant include: menthol (i.e. mint camphor), menthone, etc., among which menthol is the main component, a colorless crystal with a distinctive aroma. Increasing the yield of mint oil and menthol depends on the one hand on correct agricultural techniques (such as the correct harvest period and rational fertilization); on the other hand, selecting and planting superior varieties is a key issue in mint production.

Main growing and cultivation regions: Mainly produced in Jiangsu, Jiangxi, Sichuan, Hebei, Shaanxi, Shandong, and other provinces. Cultivated throughout the country.

[Plant Morphology]

Perennial herb, plant height 30-80cm, the whole plant has a cool fragrance. Underground rhizome white, creeping, with clustered fibrous roots at the nodes. Aerial stem erect or leaning outward at the base, square, hollow, with nodes. Simple leaves alternately opposite, ovate or oblong, margins finely serrate, both surfaces with sparse soft hairs and yellow glandular dots. Verticillaster axillary. Corolla pale red or purple, labiate; stamens 4; pistil 1, ovary 4-lobed. Nutlets 4, borne within the persistent calyx. Flowering period August-September, fruiting period September-October (Figure 35).

[Biological Characteristics]

Mint prefers a warm and humid environment; rhizomes sprout and emerge at 5-6°C, and the suitable growth temperature is 20-30°C. Cold-tolerant; underground rhizomes can still overwinter safely at -30 to -20°C. During the growing period it prefers sufficient sunlight; the early and middle stages require more water, and the budding and flowering stage needs dry environmental conditions. It has low requirements for soil; generally any soil can be used for planting. Mint has strong adaptability. In the early growth stage it prefers humidity; after the plants close the rows, slightly dry conditions are better. The budding and flowering stage prefers sufficient sunlight and a dry climate.

Mint is a long-day plant. Long daylight can promote flowering and increase the accumulation of mint oil and menthol.

[Planting Techniques]

1. Site selection and land preparation: Choose a sunny, flat, fertile, well-drained sandy loam plot, apply 5000kg of barnyard manure per mu and 50kg of compound fertilizer, deep plow 20cm, harrow fine and level, make flat beds or raised beds 1m wide, open 4 small furrows 3cm deep in the bed, and wait for planting.

2. Propagation methods

(1) Varieties: At present, among many cultivated varieties, the two varieties Qingjing Yuanye (green stem round leaf) and Zijing Zimai (purple stem purple vein) are the most superior, with high yield and high volatile oil content. They can be planted in front of and behind houses and in courtyards.

In recent years, the 73-8 mint bred by the Shanghai Institute of Spice Industry Science has many branches, short internodes, large leaves, and relatively dense distribution of glandular scales. The oil yield of fresh grass is 0.3%-0.51%, the oil yield per mu is 9.75-15.22kg, and the menthol content is 80.13%-87.6%. It is a high-yield variety and has been widely promoted and planted in production areas.

(2) Propagation: In production, the rhizome propagation method is generally used. Shandong and other places mostly plant in spring, while Jiangsu and Zhejiang regions plant in winter. Spring planting is between "Spring Equinox" and "Qingming", and winter planting is from late October to early November. When planting, dig out the rhizomes left in the field that have not been dug up, or use the rhizomes that have been dug out and covered with moist soil in winter. Select rhizomes with short internodes, white color, thick and strong, dense nodes, and no pests or diseases. Cut into 6-10cm long segments, place them into the opened furrows at a row spacing of 24cm and plant spacing of 8cm, cover with soil and compact, and water thoroughly with a large amount of water. Rhizomes should be dug, cut, and planted at the same time to prevent excessive water loss from affecting survival. Use about 60-100kg of seed rhizomes per mu. Generally, 1 mu of mint seed roots can be divided and planted in 5-10 mu.

3. Field management

(1) Watering and fertilizing: Mint grows rapidly, and the number of harvests per year also differs by region. In order to accelerate mint growth and increase mint yield, sufficient fertilizer must be applied. In Sichuan, base fertilizer is generally mainly barnyard manure, cake fertilizer, and bone meal. In addition to base fertilizer, topdressing still needs to be carried out on time. After mint emerges, loosen the soil and weed frequently to keep the field clean. Also, water lightly and frequently, and water whenever there is drought, so as to keep the soil moist and promote stem and leaf growth. When the seedlings are 15cm high and after each harvest, apply topdressing in time, mainly nitrogen fertilizer (15kg urea per mu) or 1500kg human manure and urine per mu plus 8kg ammonium sulfate, add 50kg water, and apply it in furrows beside the seedlings. Supplement with phosphorus and potassium fertilizer (10kg diammonium phosphate). Water after application to promote rapid stem and leaf growth.

(2) Pest and disease control

1) Rust disease: The pathogen is a polysporous fungus among fungi, damaging the leaves. In the early stage of the disease, orange-yellow powdery summer spore piles appear on the back of the leaves, and later dark brown powdery winter spore piles are produced. In severe cases, the leaves wither and fall off. The disease is severe in the rainy and high-temperature season in May.

Control method: Drain accumulated water in the field in time to reduce soil moisture; in the early stage of the disease, spray 25% triadimefon 1000-fold solution, continuously 2-3 times.

2) White star disease: Also known as leaf spot disease. It is caused by Septoria fungi among fungi, damaging the leaves. It occurs from May to October. At the beginning of the disease, nearly circular dark green lesions appear on both sides of the leaves, then continuously expand and become dark brown, and later fade to gray-white, appearing like white stars, with small black dots forming on them, causing the leaves to wither and fall off.

Control method: In the early stage of the disease, spray 25% carbendazim 1000-fold solution, use at most 2 times per crop season, and the interval between the last application and harvest should be no less than 5 days; or use 1:1:150 Bordeaux mixture, used alternately, with good effect.

4. Selection and breeding of superior varieties

Select the two robust-growing varieties Qingjing Yuanye and Zijing Zimai as superior varieties. In winter, water once with freezing water before the freeze-up, and dig them out again when planting in the following spring. It is also possible to dig out the rhizomes before the freeze-up, tie them into small bundles, bury them deeply or overwinter them indoors covered with moist soil, for use in planting the following spring.

[Harvesting and Processing]Mint is harvested 2 times each year in Jiangsu, Zhejiang, Jiangxi, and other regions, and harvested 1-2 times each year in North China. The first time is at "Minor Heat", and the second time is at "Frost's Descent". In Sichuan, Fujian, and Guangdong regions, it can be harvested 3-4 times a year. Choose a sunny day with no rain in recent days, cut the mint down close to the ground with a sickle, sun-dry it in place for 2 hours, turn it over and sun-dry for another 2 hours, transport it back and sun-dry until 70-80% dry, tie into small bundles, and sun-dry until completely dry, then it can be used medicinally. It is generally considered that the first harvest in June-July is the "summer leaf", with excellent quality; the August harvest is the inferior-quality "autumn leaf".