The problem of subcritical growth of repolarization nuclei in ferroelectric crystals is considered. Following the approach of Barenblatt to the theory of equilibrium brittle cracks, a concept of cohesive forces, acting on adjacent domain walls in a region near the domain tip, is introduced. These cohesive forces are intimately related to the gradient term in the Ginzburg-Landau energy and become substantial as the separation between the domain walls compares with their thickness δ. The condition of equilibrium for a ferroelectric domain is formulated by taking into account the internal field associated with the cohesive forces. Criteria for stable subcritical growth of nuclei in non-uniform electric fields are presented in terms of a gradient modulus, which is an extension of the cohesion modulus concept of Barenblatt.