Abstract of the talk: While homogeneous Ricci flows are now fairly understood, far less is known when the orbit space is 1-dimensional (cohomogeneity-1 setting). In fact, recent works suggest that in the cohomogeneity-1 setting the flow is not as rigid as in the homogeneous case and hence more complicated singularities may appear. In the talk we focus on 4-dimensional Ricci flows invariant under the cohomogeneity-1 action of SU(2) and whose restrictions to any principal orbit are Berger spheres. We discuss singularity formation and long-time behaviour of such flows.