  We present a flavour-covariant formalism for scalar triplet leptogenesis,
which takes into account the effects of the different lepton flavours in a
consistent way. Our main finding is that flavour effects can never be neglected
in scalar triplet leptogenesis, even in the temperature regime where all
charged lepton Yukawa interactions are out of equilibrium. This is at variance
with the standard leptogenesis scenario with heavy Majorana neutrinos. In
particular, the so-called single flavour approximation leads to predictions for
the baryon asymmetry of the universe that can differ by a large amount from the
flavour-covariant computation in all temperature regimes. We investigate
numerically the impact of flavour effects and spectator processes on the
generated baryon asymmetry, and find that the region of triplet parameter space
allowed by successsful leptogenesis is significantly enlarged.
