The large white trumpet-shaped flowers of Easter lily (Lilium longiflorum) are a tradition this time of year. These plants are forced to bloom at the appropriate time for the religious holiday, completely out of their normal flowering time.
Native to the three small southern islands of Japan (Liu-chiu/Ryukyu Islands), this species was distributed to other parts of the world a long time ago. It was being cultivated on the mainland of China and Japan when early western explorers reached the area. In 1777 the famous plant explorer Carl Peter Thunberg discovered this lily and sent it to England in 1819. By the 1880s, bulbs were being grown commercially in Bermuda for shipment to the US, but by the turn of the century Japan dominated the US export market. When the supply of stock from Japan was cut off when World War II began with the bombing of Pearl Harbor, prices rose, making commercial cultivation of these bulbs economically feasible in the US.
Today almost all of the potted plants grown as Easter lilies are produced by less than a dozen growers located in a narrow coastal region along the border of California and Oregon. Bulbs are grown for three or four years, replanted each year in the fields of this area with the perfect growing conditions, until they reach the right size and maturity. They are then shipped to commercial greenhouse growers throughout North America, where they are forced under controlled conditions to flower in time for Easter.
Since Easter falls on a different day each year (the first Sunday following the first full moon of the vernal equinox, which may be anywhere between March 22 and April 25), careful scheduling is critical to ensure they are at the perfect stage during the approximately two-week marketing window.
Source: Wisconsin Horticulture, University of Wisconsin-Madison