The study investigates the genetic basis of vernalization in winter wheat and barley, focusing on the vernalization gene *VRN3*. It demonstrates that *VRN3* is linked to a gene similar to *Arabidopsis FLOWERING LOCUS T (FT)*. The transcript levels of *HvFT* and *TaFT* are significantly higher in plants homozygous for the dominant *Vrn3* alleles (early flowering) compared to those with the recessive *vm3* alleles (late flowering). In wheat, the dominant *Vrn3* allele is associated with a retroelement insertion in the *TaFT* promoter, while in barley, mutations in the *HvFT* first intron differentiate plants with dominant and recessive *VRN2* alleles. Transformation experiments with the *TaFT* allele carrying the promoter retroelement insertion in winter wheat plants resulted in significantly earlier flowering, confirming the identity between *TaFT* and *VRN-B3*. Statistical analyses confirmed significant interactions between vernalization and *FT* allelic classes in both species. These findings suggest that *FT* genes are responsible for natural allelic variation in vernalization requirement, providing additional sources of adaptive diversity for economically important crops.The study investigates the genetic basis of vernalization in winter wheat and barley, focusing on the vernalization gene *VRN3*. It demonstrates that *VRN3* is linked to a gene similar to *Arabidopsis FLOWERING LOCUS T (FT)*. The transcript levels of *HvFT* and *TaFT* are significantly higher in plants homozygous for the dominant *Vrn3* alleles (early flowering) compared to those with the recessive *vm3* alleles (late flowering). In wheat, the dominant *Vrn3* allele is associated with a retroelement insertion in the *TaFT* promoter, while in barley, mutations in the *HvFT* first intron differentiate plants with dominant and recessive *VRN2* alleles. Transformation experiments with the *TaFT* allele carrying the promoter retroelement insertion in winter wheat plants resulted in significantly earlier flowering, confirming the identity between *TaFT* and *VRN-B3*. Statistical analyses confirmed significant interactions between vernalization and *FT* allelic classes in both species. These findings suggest that *FT* genes are responsible for natural allelic variation in vernalization requirement, providing additional sources of adaptive diversity for economically important crops.