Protoplanetary disks are thought to be the main sites of planet formation, and to understand how planets form we need to understand the physical processes in these disks. One of these physical processes is turbulent mixing, which is the main driver of disk accretion. It also manifests itself in dust settling and grain growth — the first steps of planet formation. However, the strength of turbulent mixing is not well known, both from a theoretical as well as an observational point of view. I will show how the turbulent mixing strength can be constrained from unresolved SEDs using radiative transfer codes, and how this leads to the conclusion that the first steps of planet formation are independent of stellar mass.