Last winter I planted a large container with several layers of bulbs (crocus, muscari, narcissi, daffodils, tulips). I wanted to repeat this display next year, and emptying the container to retrieve the bulbs and repeating the process to replant them seemed like a double waste of time effort.
So I left the foliage to die down naturally, then cut it down and sowed annual flower seeds for a summer display.
This was not a success. The seeds germinated fine, but the seedlings stopped growing when they were a 2 to 3 inches (5 - 10 cm) tall and just "sat there doing nothing".
There were no obvious signs of disease or pest damage. After more than half a century of gardening, I don't think I made any "beginner mistakes" over watering, feeding, etc!
I wonder whether the bulbs themselves were inhibiting root growth in the seedlings. Bulbs certainly naturalize well under grass in the UK, but grass isn't exactly a "typical" plant species of course.