The object of present invention is to provide a polyvinyl alcohol film for growing plants capable of inhibiting penetration of root and having excellent permeableness of nutrient, a method for preparing the same, and a method for growing plant by using the same.The solution is to provide a polyvinyl alcohol film for growing plants, the average value of birefringence of mechanical direction in the direction of thickness of the film is 4.0×10-3 ~ 12.0×10-3, and swelling degree is 150 ~ 180% a method for preparing the polyvinyl alcohol film for growing plants, comprising a extending step that extends the polyvinyl alcohol film with moisture content of 5~20 mass% to be 1.3~1.7 times, and a thermal treatment step that the thermal treatment of extended film is carried out in the range of temperature of 130~170℃ and a method for growing plant by directly contacting the polyvinyl alcohol film for growing plants with plants.本發明之課題在於提供一種可抑制根的貫穿,且養分穿透性亦優良的植物栽培用聚乙烯醇薄膜、其製造方法及使用其之植物栽培方法。解決手段為一種植物栽培用聚乙烯醇薄膜,其機械行進方向之雙折射率於厚度方向的平均值為4.0×10-3~12.0×10-3、膨潤度為150~180%;一種植物栽培用聚乙烯醇薄膜之製造方法,其包含將含水率(moisture contents)為5~20質量%的聚乙烯醇薄膜拉伸1.3~1.7倍之步驟、及對經拉伸之薄膜以130~170℃之範圍內的溫度實施熱處理之步驟;及一種植物栽培方法,其係以使植物與上述植物栽培用聚乙烯醇薄膜直接接觸的方式來栽培植物。
