长春市地处北纬43°55′,年平均气温48℃,最低气温-39.8℃,年日照时数2668小时,无霜期140—150天。冬季塑料大棚内地温和气温均很低,冻土层要到5月中下旬才能化通。采用覆盖耐低温抗老化农膜越冬的塑料大棚(或称越冬棚)能有效的提早化冻时间,使地温较快回升,提早菜苗定植时间。据实测,越冬棚2月份的冻土深度只有76厘米,比露地冻土层156厘米浅80厘米,冻土化通时间在3月下旬,而春季扣膜(2月末或3月初覆膜)的棚则在5月10日以后;10厘米深的地温稳定超过10℃的时间,越冬棚在3月下旬,而春季扣膜棚在4月17日以后。可见塑料大棚扣膜越冬是北方地区提高棚温的有效措施。1989年长春市推广的越冬棚已达全市大棚的16.8%。扣膜越冬的棚型越冬棚的结构与通常的塑料大棚相同,面积以一亩为宜,过大会给通风及病虫害防 Changchun City is located at latitude 43 ° 55 ’, with an annual average temperature of 48 ℃, a minimum temperature of -39.8 ℃, annual sunshine duration of 2668 hours and frost-free period of 140-150 days. Winter plastic greenhouse mild temperature in the Mainland are very low, permafrost until mid to late in May to pass. Cover with low temperature resistant anti-aging plastic film overwintering plastic greenhouse (or winter shed) can effectively premature thawing time, the ground temperature faster recovery, early seedling colonization time. According to the actual measurements, the depth of the frozen soil in February overwintering shed was only 76 cm in February, 80 centimeters more than 156 centimeters of frozen soil in the open field, and the permafrost pass time was in late March. In the spring, the frozen membrane (covered in late February or early March) The shed was after May 10; 10 centimeters deep geothermal stability of more than 10 ℃ time, winter shed in late March, while the spring buckle shed in the April 17 after. Can be seen plastic film buckle winter over the winter greenhouse is an effective measure to improve the greenhouse temperature. The winter shed in Changchun City in 1989 reached 16.8% of the city shed. Cloak overwintering shed winter shed structure and the usual plastic shed the same area of ​​an acre is appropriate to the General Assembly for ventilation and pest control