If at all possible, I would leave them in the house hopefully to condition at 65 to 75 degrees for 3 weeks. Your garage might be a bit cool. They may carbonate in the garage but it will take longer.
How well it will carbonate depends on what kind of yeast you're using and how long you plan on leaving it. Some Ale yeasts will work in the 50's, some will be much slower. I personally leave mine in a cool dark closet in my house, but it still stays at about 65 degrees.