Nadal, who is No. 4 in the world, hasn't played since last June because of a knee injury and stomach virus and Ferrer, fifth in the rankings, on Tuesday earned a semifinals berth in the Australian Open against No. 1-ranked Novak Djokovic.
Spain plays Feb. 1-3 at Vancouver, British Columbia, in a best-of-five, first-round series. The Spaniards were runners-up to Croatia last year but won the Davis Cup five times from 2000 to 2011.
Spanish captain Alex Corretja said he plans to go with world No. 11 Nicolas Almagro in singles with Marcel Granollers and Marc Lopez penciled in for the doubles match. Albert Ramos was also nominated for the Canada series.
Canada has announced that 15th-ranked Milos Raonic will play next week along with Vasek Pospisil, Frank Dancevic and Daniel Nestor.