Gardening. In the foreground gardeners are pruning, left, and staking a potted plant, right. In the background a third man is adjusting the cover of a cold frame. The cover had a dual purpose as it could be used to exclude light when a crop was being blanched, or to act as insulation in cold weather. Illustration by Oscar Pletsch (1830-1888) German illustrator, particularly of children's books. (1871). Chromolithograph.