No, it is generally not recommended to put landscape fabric under compost or topsoil, as this creates a barrier that defeats the purpose of the topsoil and harms plant health. The fabric stops plant roots from growing deep into the native subsoil, which limits their access to moisture and nutrients and can lead to stunted, unhealthy plants.
The barrier also blocks the natural, beneficial movement of earthworms and microorganisms from the subsoil up into the topsoil, which is critical for aeration and building long-term soil health. Over time, weeds will simply root into the topsoil on top of the fabric, leaving you with a root-bound, unhealthy garden that is very difficult to manage or correct.
