Flower pot

Flower pot is a slang term for an aerial shell exploding in it's mortar. When this happens, the effect will be like a mine. Since a flowerpot is not a desired effect, the aerial shell is sometimes powerful enough to break the mortar. Most commonly this is caused because;

1. The shell is loaded upside down in the mortar and the lift charge is on top.
2. The mortar tube is too small and the shell gets stuck.
3. The lift charge escapes around the time fuse or spolette and ignites the bursting charge, before the shell is lifted up in the air.

Flower pots must not be confused with a firework mine. Mines are designed as a ground effect to produce a upward spray of stars. When an aerial shell flower pots, it can destroy the mortar and damage the mortar rack it is in, possibly causing errant shells to be fired into spectators or technicians working the display.