Simple physics realization:
The force of water falling from a steep roof run-off is equal to the decimation potential of several flats of tender, just-sprouted seedlings positioned directly underneath.
This has been established through scientific process by a beginning gardener whose IQ must have temporarily plummeted to double digits, and who will now have to wait several more weeks (again!) for a decent salad harvest. (Sigh)
Please do not leave any infant plants in her care without adult supervision...
“Common sense is genius dressed in its working clothes.”Ralph Waldo Emerson
(Who probably grew great lettuce in a protected location...)