The Mother Jones article presents this as a quote from RFK where he does use the word "farm". The context of the article is a virtual "Latino town hall" event, so I assume that's where he said the following:

I’m going to create these wellness farms where they can go to get off of illegal drugs, off of opiates, but also illegal drugs, other psychiatric drugs, if they want to, to get off of SSRIs, to get off of benzos, to get off of Adderall, and to spend time as much time as they need—three or four years if they need it—to learn to get reparented, to reconnect with communities.