use filtered water like from a Pure or Brita. Your soap water probably came from the same source as your plain water. whatever the cause, they all got it. Water is the first obvious factor to me. Next would be fertilizer.
If it was a disease like Fusarium, using sterile soil might eliminate this. Bake it in the oven before using. This might not eliminate everything, but using fresh potting soil bought from a store could help.
use filtered water like from a Pure or Brita. Your soap water probably came from the same source as your plain water. whatever the cause, they all got it. Water is the first obvious factor to me. Next would be fertilizer.
If it was a disease like Fusarium, using sterile soil might eliminate this. Bake it in the oven before using. This might not eliminate everything, but using fresh potting soil bought from a store could help.
Interesting experiment.