Use Clubs Bag Before Putting in Garage
It is better if you use the golf clubs bag before leaving them at a safe place in the garage. Make sure the place is dry and clean so that the bag does not catches dampness or fungus etc. You can even think of hanging the bag in a corner if the garage's height is substantial.
You can leave your golf clubs in the boot or trunk of your car for a couple of days or even more but be assured that the car is going to be stationary during this purpose. This can be the case if the car is only in your use, but in case it is in use of the entire family then do not take risk of leaving the golf clubs in the car trunk. They will hit each other while the car is running on the roads and develop scratches. So think of the possibility again.
Inspection and Cleaning
Wherever or however you store golf clubs in the garage, make sure you inspect them regularly and clean them. The exercise will also allow you to check if the clubs are catching any dampness or damage through other means. If you just leave them at a place for a longer period of time without any inspection it is likely they will develop dampness and start ripping apart at the grip part.
Leaving Them Out
If you suspect chances of catching some dampness at the grip part of golf clubs that you can feel when cleaning, you can leave the clubs out in the sun for a while so that they can get dried, and then store them again. The process is especially recommended if you are storing the clubs for a longer period of time.