Working in the greenhouse this weekend, I performed the daily tasks so everyone else could be home. One task is checking the germination chamber twice each day. The seed flats are left in only to the point of germination. The seeds do not sprout at the exact same time. Depending on the seed, they germinate over a range of time from one day to several weeks. So, when the first few seedlings are seen, we move that flat to the greenhouse.
Germinating seeds is more like fun than work. From so little, so many plants spring forth (no pun intended). The germination chamber is great for seeds, but disastrous for seedlings, they quickly stretch and are to weak to stay upright. That is why we check twice a daily, even one day in the germination chamber will ruin seedlings.
The seedlings pictured were my amazement for the day. At 8:00 AM there was no plant life visible in these flats. When I returned at 4:00 PM the tomatoes, moonflowers, and morning glories had all grown to one-inch tall seedling! That is some fast growth!