Mexico gave us the Aztecs, the delicious tacos and very large hats. It also gave us Euphorbia pulcherrima, which is now as closely linked to Christmas as the holly, ivy, turkey, and black cake. In Europe and North America production of the poinsettia is worth hundreds of millions of dollars each year. The process of initiating flower production starts to happen in August and September when cuttings from stock plants are rooted in mist propagators and grown on for marketing in December. The main flower initiation starts at the autumn equinox, and some in mid-August, and those glorious red flowers appear about ten, eleven, twelve or thirteen weeks later depending on the variety. When this happens any of these varieties will produce flowers too early for Christmas, and so growers manipulate the day length to