We extend micromagnetic nucleation theory by removing the customary constraint of rigidity. The magnetoelastic interaction is added to the magnetic free energy as a perturbation and it is evaluated for various competing nucleation patterns or their linear combinations to determine the pattern yielding the lowest energy. We apply this technique to the initiation of magnetization reversal in long cylindrical particles and we compute the reduction of the nucleation field for curling and buckling as a function of particle radius. We find that the radial ranges over which curling and buckling are favored are nearly unaffected by magnetostriction if the particles are free, but that buckling is dominant over a slightly extended range of radii for particles imbedded in a matrix, as in a permanent magnet. We determine the nucleating domain pattern of a platelet with easy axis perpendicular to the faces, initially saturated by a large in‐plane field. The domain nucleation threshold depends on the thickness, anisotropy, and magnetoelastic coupling of the plate. The nucleation mode has incipient stripe domains parallel to the field (the mode always predicted in the absence of magnetostriction) in thin plates, perpendicular to the field in thick plates, and inclined with respect to the field in the intermediate thickness range.