Ferdinand missed the World Cup with a knee ligament injury and has spent the last weeks in rehabilitation.
Ferguson told The Sunday People: “Rio is nowhere near, no. He’s doing little bits of jogging and things like that but I think he’s a month away.
“We always anticipated it would take time. It’s a knee ligament and, although it wasn’t what you’d call a serious one, it was a hard one. You have to take time with knee ligaments.”
The Scot added: “Rio has had a bad 12 months and we hope it gets better for him.
“You hope the break over the summer with missing the World Cup will help him.
“The back injury seemed to sort itself out as the season went on, then he had the groin injury.
“He’s had a succession of these things and you don’t want to see that when a player is in his thirties.”