Northern single-crop region (Region I)
In this region, a one-crop-per-year cropping systems predominates. Spring planting is in April or early May and fall harvesting is in September or early October . This region is best suited to middle- or late-season varieties, although suburban, forestry and mining area producers also plant early varieties to meet the vegetable needs of nearby markets. Tubers are commonly stored for six months or longer, mostly in underground cellars.
Central Plain double-crop region (Region II)
The main seasons for potato cultivation are spring and fall, thus the region’s double cropping designation. The growing season varies from 180 to 280 days. Because the summer is long and hot, it is not well suited for potato cultivation. Potatoes for consumption are sown between late February and early March and harvested between late May and mid-June. Force-sprouted tuber are replanted in August and harvested in November for use as seed stock for the spring crop. Because the region covers 15 degrees of latitude, and its complex topography, planting times differ greatly; potato is sown in the north on the Liaodong Peninsula as late as early April and as early as early February in the south, at the Hangzhou Strait.
For the varieties that were available in the past the main spring and fall growing seasons were only 90 days and it was imperative that producers use early maturing varieties with short dormancy periods. With the development of new cultivars that have the are better adapted to this zone, this is not longer true (Heilonggjiangshen Keshan Nongye Kexue Yanjiusuo, 1976).
Southern double-crop region (Region III)
The zone is characterized by short growing seasons in the cool season. Fall potato is sown in late October with harvests at the end of December or the beginning of January. Winter potato is sown in mid-January and harvested in early to mid April. Intercropping is convenient because potato has a short growing cycle. Also, because the region suffers little frost damage, the sowing period can be changed to meet the needs of intercropping.
Southwestern Mixed single and double crop region (Region IV)
Potato sown area in Region IV is more than 30% of the national total. Because of complex differences in elevation, topography, climate, and soils, cultivation systems vary widely. Production in the high mountains above 2,000 m tends to be low because of the prevalence of late blight, poor soils, and the limited use of inputs.
