Depends how thick the mulch is...

I say in my profile " never underestimate the power of a plant." With that said if your mulch is the average of 3 to 4 inches in depth there shouldn't be a problem in them punching through.

depends on how deep you planted the tuber and if it has survived the winter in the ground. buried 6 or more inches deep has in past seen some come through unscathed.