"seph..." wrote

They all seem to be suffering from the same thing and I would hazard a guess
the ground was not dug over and loosened to enough depth before planting or
it may be your ground packs down hard easily. Carrots like a soft soil so if
you have clay it needs lots of organic matter or sand to open it up.
Alternatively make a raised bed.

-- Regards
Bob Hobden
W.of London. UK