C.R.S. § 4-2.5-204

(1) A lease contract may be made in any manner sufficient to show agreement, including conduct by both parties which recognizes the existence of a lease contract. (2) An agreement sufficient to constitute a lease contract may be found although the moment of its making is undetermined. (3) Although one or more terms are left open, a lease contract does not fail for indefiniteness if the parties have intended to make a lease contract and there is a reasonably certain basis for giving an appropriate remedy.