Domestication and genetic improvement of trees is far behind that of herbaceous plants owing to their long generation times, which result from the existence of a long juvenile phase of reproductive incompetence. During recent years, significant progress has been made towards understanding the molecular basis of flowering transition in model herbaceous species. Some of the genes identified have been shown to efficiently accelerate reproductive development when ectopically expressed in transgenic plants, including trees. These results provide new clues as to the molecular basis of reproductive competence in trees and suggest ways to accelerate their genetic improvement.