Photos by Michael Yamashita yamashitaphoto / Plastic solar greenhouses dominate the landscape along the Great Wall in northwest China, making farming a year-round occupation. Keeping a hot house warm in winter requires a blanket made of rice straw for insulation. Raised at dawn to capture the sun and lowered at sunset to slow heat loss, the inside temperature stays warm enough to grow cucumbers in near freezing temperatures. China accounts for more than 90 percent of passive solar greenhouse use worldwide. #greenhouses #hothouse #passivesolar #greatwall #greatwallofchina