Looking at this from an instructors point of view; I teach environmental science at a Junior college I would increase the temperature to at least 70 degrees...
Temperatures found in your garage will not allow cellular respiration to perform correctly; in other words the cold water creates an atmosphere that will not allow sexual activity of the correct temperature for reproduction.
What you end up doing is inviting a cold water species bacteria to multiply and proliferate your live rock.
End result is live rock indigenous for cold water species say from the California coast; that is something you do not want, that is unless you don't plan on keeping warm water reef tropical fish and corals.
Just my two cents...
MG