Nonlinear growth behavior was observed in two crystallization regimes, depending on the temperature. Non-linearity may be explained by the reduction of the concentration of crystallizable ethylene sequences (CES) in the melt phase. In the two regimes, the concentration of uncrystallizable ethylene sequences (UCES) increases, as the crystallization time increases, because UCES are continuously excluded from the crystal lattice into the melt phase. An empirical equation is proposed to describe the melting temperature of the crystal stem with the maximum possible length, T-m(C,n*), in nonlinear growth processes, assuming that the diffusion layer is negligible. A modified form of the Hoffman-Lauritzen equation (MHL) describes well the crystallization growth kinetics of LLDPE spherulites in the non-linear growth region.