Dutch Tulip Farmers grow around two billion tulips every year. The Flowers come into full bloom for three to four weeks a year, between April and May. Once the tulips are in full bloom, the farmers run cutting machines through their fields, lopping off the colourful flower heads. This is done so that the remaining energy of the flower gets directed back to the bulb so that it will bloom better and stronger. Mainly the tulip bulbs are sold, rather than the blooming flower head itself. In 2015 a total of 926 different tulip cultivars were bred. The Dutch horticulture sector is the world market leader in flowers, plants and bulbs. Some 77% of all flower bulbs traded worldwide come from the Netherlands.