Thanks for your replies! The peat it's there from the past year, it' a spot that rarely gets rain water (I have Always afternoon there, and never bloomed of grow bigger). So maybe it got too dry. I was going to discard all the clay soil I dug but I kept a pot of it and see if I have to add more on that spot.
All in all I guess I prefer clay to peat.. it just seems too "dead"!
