In the spring the bulb sends up a growth tip. For a period this new growth is encouraged. Then in June the farm hands swarm the field and pick off the flowers so that the remaining growth is channeled back down to the foliage and bulb. At this point in a lily bulb's life it measures only slightly larger than when first planted.
but before they are covered, rafts of fast hands turn and place each bulblet so as to optimize growth when it comes in the spring.