For every visitor to tulip fields it is a strange and special sight;

during or after flowering, all tulip heads are removed. The reason for this is simple; as a nursery we would like to have beautiful strong bulbs! If the heads are not removed, then all the energy goes to the seed buds of the flower. This is not what we want because enhancing in this way takes 7 to 10 years and we don't not know what the outcome is because the pollination of another tulip may have taken place; it is therefore possible that you cross a red tulip with a yellow tulip in this way. For that reason we remove all flowers heads; in this way, the tulip will put all its energy into growing the underground parts, the bulbs. These bulbs are being harvest in June and the small bulbs are the new planting material, for all fields that are in bloom again the following year. And the large bulbs are sold for flower production or for the consumers market. Then you can enjoy a beautiful vase of tulips or tulips in your garden. 

Nowadays, the tulip heads are removed mechanically. The machine uses its rotating blades to knock off the flowers just below the head. The machine can be adjusted in height so that it is suitable for all sorts of tulips. If the machine is too low, it also damages the leaf and that is detrimental to the growth of the bulb, too high, then too many tulips remains.
In the early days, it was very different. The tulips heads had to be removed by hand, piece by piece. The heads then went in boats to the bulb barn to prevent the possible spread of diseases, that was the thought at that time. Nowadays we leave the heads in the paths and they serve as a kind of green fertilization.