An aerial photo taken on Dec 5 shows strawberry greenhouses in Shanting district of Zaozhuang, East China's Shandong province. In recent years, the region has developed a greenhouse economy, enabling farmers to grow crops year-round. [Photo by VCG/dzwww.com]

Tourists pick strawberries at a greenhouse in Shanting district, Zaozhuang, East China's Shandong province on Dec 5, 2019. Winter is the harvest season for strawberries. [Photo by VCG/dzwww.com]

A bee collects nectar at a strawberry greenhouse in Shanting district, Zaozhuang, East China's Shandong province. [Photo by VCG/dzwww.com]

Strawberries are grown at a greenhouse in Shanting district of Zaozhuang, East China's Shandong province. [Photo by VCG/dzwww.com]

Strawberries ripen at a greenhouse in Shanting district, Zaozhuang, East China's Shandong province. [Photo by VCG/dzwww.com]