Detailed Explanation of the Key Points of Standardized Cultivation Techniques for Snow Peas

Snow pea (scientific name: Pisum sativum var. saccharatum) belongs to the Fabaceae (Leguminosae) genus Pisum. It is an annual twining herb, 90-180 cm tall. Snow pea is also known as heren dou and jian dou, and belongs to the family Leguminosae, genus Pisum. It is grown mainly for its tender pods, and originated along the Mediterranean coast and in western Asia. The tender pods of snow peas are crisp and fragrant, with very high nutritional value.

Growth habits of snow peas

Light requirements: Snow peas are long-day plants. Most varieties can flower earlier when the photoperiod is extended, and flower later when the photoperiod is shortened, but some early-maturing varieties are not strict about light requirements. Generally, varieties require relatively strong light and a relatively long photoperiod during the pod-setting stage, but they are not suited to high temperatures, and are suitable for planting during the transition period between spring and summer.

High water demand: Snow peas require a relatively large amount of water throughout the entire growth period. During seed germination, if soil moisture is insufficient, the seeds cannot absorb water and swell, which greatly delays emergence. The seedling stage can tolerate a certain degree of dry climate. If air humidity is too low during the flowering stage, it can cause flower and pod drop. If high temperature and drought occur during the pod growth stage, the pod fibers harden prematurely, causing premature maturity and reducing quality and yield. Therefore, throughout the entire growth period of snow peas, a sufficient water supply is necessary for vigorous growth, large pods and full seeds, and guaranteed quality and quantity. However, they are not tolerant of waterlogging; if there is too much water, seeds are prone to rotting after sowing, roots are prone to rotting at the seedling stage, and diseases are prone to occur during the growth period.

Soil conditions: Although snow peas are not strict about soil requirements and can be planted in well-drained sandy loam or newly reclaimed land, loose neutral soil containing organic matter is preferable, and growth is best in soil with a pH of 6.0-7.2. When soil acidity is below pH 5.5, diseases are more likely and the pod-setting rate decreases, so lime should be added to improve it. Pea roots are deep and slightly drought-tolerant but not moisture-tolerant; poor drainage at sowing or during the seedling stage easily causes root rot, and drought during the flowering stage leads to poor fertilization and easily forms empty pods or shriveled pods. Snow peas should not be continuously cropped, and generally require at least 4-5 years of rotation.

Cultivation and sowing timing: According to stem growth habits, snow peas can be divided into three types: dwarf, semi-vining and vining. In the Yangtze River basin, for spring cultivation, sow in mid-to-late February. For autumn cultivation, sow in mid-to-late August. For overwintering cultivation, sow successively from late October to early November. In the north, it is generally spring-plowed and summer-harvested, and can also be used for early spring and autumn cultivation.

Snow peas are semi-cold-tolerant vegetables and are not heat-tolerant. At 4 degrees Celsius, seeds begin to germinate slowly, and at 16 degrees Celsius to 18 degrees Celsius they can emerge in 4 to 6 days. Seedlings can tolerate low temperatures of minus 6 degrees Celsius, the optimum temperature for stem and vine growth is 15 degrees Celsius to 20 degrees Celsius, and the optimum temperature during the flowering and pod-setting stage is 15 degrees Celsius to 18 degrees Celsius; when it exceeds 26 degrees Celsius, yield and quality decrease. The pod-setting stage requires long daylight and relatively low temperatures, and high temperatures should be avoided.

Standardized cultivation techniques for snow peas

Variety selection

Snow pea varieties include Zhongshan Qing, Chihua Juanjia, Lianyang Shuanghua, American Xiao Qinghua, Japanese Chengju and other varieties. Varieties can be selected according to the needs of each region.

Cultivation season and method

For early spring solar greenhouse cultivation, sow from late January to early February, and harvest from late April to mid-June. For early spring plastic tunnel cultivation, sow from late February to early March, and harvest from early-to-mid May to mid-to-late June. For spring open-field cultivation, sow from mid-to-late March, and harvest from mid-May to late June. For delayed autumn solar greenhouse cultivation, sow in late July, and harvest from mid-October to mid-December. For delayed autumn plastic tunnel cultivation, sow in early August, and harvest from mid-October to mid-November.

Cultivation techniques

1. Land preparation and sowing:

Direct sowing is the main method, with ridge planting or bed planting. Before sowing, apply 2000 kg of organic fertilizer and 20 kg of superphosphate per mu, then plow, level and make ridges or beds. To promote early maturity and lower the flowering node, seeds can be soaked and pre-germinated before sowing: soak the seeds at room temperature for 2 hours, then treat them at 5 degrees Celsius to 6 degrees Celsius for 5 to 7 days, and sow when the sprouts grow to 5 mm. After sowing dry seeds, water promptly. Use drilling: row spacing 30 to 40 cm, plant spacing 8 to 10 cm, cover with soil 2 to 3 cm. The seeding rate per mu is 15 kg for dwarf types and 12 kg for vining types.

2. Field management:

Do not water before emergence. During the vegetative growth period after emergence, focus on intertillage and weeding, and water appropriately, as long as the soil does not crack from dryness. For vining types, set up supports when the vines are 30 cm long. Water lightly before budding, and do not water during the flowering stage. Snow peas have nitrogen-fixing ability and do not need much fertilizer, but most varieties have strong growth vigor and are planted at high density, so generally 3 topdressings are needed. The first is applied during the vigorous vine-growing stage, with 15 kg of compound fertilizer per mu, or 400 kg of human feces and urine; during the pod-setting stage, apply phosphorus and potassium fertilizer, with 15 kg of diammonium phosphate per mu and 5 kg of potassium sulfate or potassium chloride, which has an obvious yield-increasing effect. When the plants grow to 15 nodes, pinch the growing tips and remove the lower old leaves and yellow leaves to improve ventilation and light transmission. To prevent flower and pod drop, spray with 30 mg per liter of 4-CPA.

3. Harvest:

Tender shoots can be harvested at any time. About 10 days after flowering, when the tender pods are fully enlarged but the seeds are not yet full and the color is bright green, the tender pods can be harvested from the base. For hard-pod varieties, generally only green beans are harvested, when the pod skin is white-green and the beans are large and full. To harvest dry beans, do so 30 to 40 days after flowering when the pod skin turns yellow; harvesting should be done in the early morning to prevent the pod skin from splitting.

Pest and disease control

Throughout the entire growth period, snow peas are harmed by cabbage caterpillars and mites, and cypermethrin and dicofol should be used. The main diseases are viral disease and rust, and control mainly uses Virus A or Virus K, triadimefon and copper preparations. Spray every 3 to 7 days, depending on the severity of the disease.