When Is the Best Time to Plant Potatoes? Sowing and Harvest Times Across China in 2017

The potato, also known as the Irish potato, is one of the world's important food crops. It is highly nutritious, easily absorbed by the human body after eating, and economically affordable, making it one of the projects through which farmers can make their fortune. So when is the best time to plant potatoes (Irish potatoes)? Let's take a look below at the best sowing and harvest times for potatoes across China in 2017.

Before learning about the best planting times for potatoes in various regions, let's first understand the potato's growth cycle!

1. Dormancy period.

After the potato is harvested, if it is placed in an environment suitable for sprouting but fails to sprout for a long time, this is physiological natural dormancy, an adaptation to unfavorable environments. Tuber dormancy begins at the moment when the tip of the stolon stops polar growth and the tuber begins to swell. The length of the dormancy period is related to the storage quality of the tuber, to whether seedlings can emerge promptly after sowing, and therefore to the level of yield.

The length of the potato dormancy period is greatly affected by storage temperature. Under conditions of about 26 degrees Celsius, depending on the variety, the dormancy period ranges from about 1 month to more than 3 months. At temperatures of 0 to 4 degrees Celsius, potatoes can remain dormant for a long time. The dormancy process of the potato is determined by the direction of enzyme activity and is closely related to environmental conditions.

2. Germination period.

Potato growth begins with the sprouting of buds on the tuber. Only after the tuber has broken dormancy do buds and shoots show obvious growth. From bud sprouting to seedling emergence is the germination period, during which the first segment of the main stem grows. The center of growth during the germination period is bud elongation, root formation, and stolon formation; nutrients and water come mainly from the seed potato and are supplied in the order of stems and leaves, then roots. The speed and quality of growth are governed by the seed potato and the environmental conditions required for germination. The time occupied by growth varies with the dormancy characteristics of the variety, the cultivation season, and technical measures, ranging from 1 month to several months.

3. Seedling period.

From emergence to the flattening of the sixth or eighth leaf, that is, the completion of the growth of one phyllotaxy, is called “tuanke” (rosette stage). This is the growth of the second segment of the main stem and constitutes the potato's seedling period. The seedling period lasts a relatively short time; whether spring or autumn cropping, it is only a short half month.

4. Vigorous growth period.

From the rosette stage to the unfolding of the twelfth or sixteenth leaf, with early-maturing varieties flowering at the first inflorescence and late-maturing varieties flowering at the second inflorescence, is the potato's vigorous growth period, lasting about 1 month and constituting the growth of the third segment of the main stem. During the vigorous growth period, the main stem begins to shoot up sharply, accounting for about 50% of the total height; the main stem leaves are fully formed, and branches and branch leaves expand. The root system continues to expand, and the tuber swells to the size of a pigeon egg. The vigorous growth period has a stage of turning point in the growth center, and the endpoint of the turning stage is marked by the ratio of stem and leaf dry matter to tuber dry matter reaching balance.

5. Tuber formation period.

This is the tuber formation period. After the vigorous growth period is completed, the plant enters the tuber formation period, dominated by tuber growth. During this period, stem and leaf growth progressively decreases, basal leaves begin to turn yellow and fall, organic nutrients from all parts of the plant are continuously transported to the tuber, and the tuber accordingly expands faster, especially fastest in the 10 days after the flowering period. The length of the tuber formation period is governed by climatic conditions, diseases, and the maturity of the variety, and is generally 30 to 50 days.

Potato planting times across China

In China, potatoes are generally planted from October to December and can be harvested from January to March the following year. Of course, if climatic conditions permit, in theory potatoes can be planted all year round, and the specific planting time must be determined according to the local climate.

1. In Northeast China and the Northwest regions such as Gansu and Qinghai, planting is generally in spring from mid-to-late April to early May (that is, after Grain Rain and before the Start of Summer among the 24 solar terms), with harvest in autumn. Usually only one season of potatoes can be planted per year, known as the northern and northwestern single-cropping region.

2. Shandong, Hebei, Henan, Shanxi, Jiangsu, Hunan, Hebei, and others. In the Central Plains areas such as Shandong and Hebei, spring potatoes are planted in February and March (after Rain Water and before the Awakening of Insects among the 24 solar terms), with the harvest season in June to July; autumn potatoes are planted in August (after the Start of Autumn and before the End of Heat among the 24 solar terms), and harvested in October to early November.

3. In some central-southern provinces such as Jiangsu and Zhejiang, spring potatoes can be planted in January and February (after Great Cold and before the Start of Spring among the 24 solar terms, when spring begins) and harvested in May and June; autumn planting takes place in September (after White Dew and before the Autumn Equinox among the 24 solar terms), with harvest in December. These regions are known as the Central Plains and central-southern double-cropping region.

4. In Guangdong, Guangxi, Hainan, Yunnan, Guizhou, and other places, after the autumn rice harvest, one season of potatoes can be planted using the interval in between. Generally sowing takes place from mid-to-late October to November (after Frost's Descent and before the Start of Winter among the 24 solar terms), with harvest in February and March of the following year. Because the growing period mostly falls in winter, these regions are usually called the southern winter cropping region.

In addition, when potatoes reproduce asexually by tuber, the seed potato can germinate and grow at a soil temperature of 5 to 8 degrees C, with the optimum temperature being 15 to 20 degrees C. The air temperature suitable for plant stem and leaf growth and flowering is 16 to 22 degrees C. The air temperature most suitable for tuber formation at night is 10 to 13 degrees C (soil temperature 16 to 18 degrees C), while above 20 degrees C formation is slow. At emergence and during the seedling period, plants suffer frost damage when the air temperature drops to -2 degrees C.

Friendly reminder:

The sign of potato maturity is that most of the plant turns yellow and gradually withers, the stolons separate from the tubers, the tuber skin forms a thicker cork layer, and the tuber stops gaining weight; then it can be harvested.

When cultivated as a vegetable in suburban areas, harvesting can be done in stages according to market demand and the maturity quality of the variety. When commercial maturity is reached——that is, when the tuber reaches 75 grams or more, it can be harvested.

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