I've had my geraniums out on the deck for about a month now and we've had a couple of nights of light frost. I'm in zone 7/8a. I bought all the geraniums at one time but only planted about half of them in the ground. The others are sitting on my deck waiting for me to figure out where to put them. The ones out there in the flower beds have been injured by the mini cold snaps we've had. They have that red foliage. But the ones up on the deck are completely fine. I didn't do anything for the plants on the deck when the cold weather hit. My deck faces west so it gets the setting sun of the day. I guess I am saying that it's probably okay to put them out on the deck depending on your zone but be prepared to cover or move them if it gets really cold again. We've had about 2 or 3 LIGHT frosts since I bought mine and again, plants on deck fine, plants in flowerbeds look a little rough. Good luck.