I'm not really sure where to put this, but socializing a newly gelded horse?

So right now my family is consider importing a horse from Germany in the next few weeks. He's a 4 year old stallion right now, but would be gelded before he left. I was wondering if the horse could be turned out with other gelding or if he would need to be left by himself? Is it horse specific, or is there a special strategy?

It depends on how he lives now and on his temperment.

He's very easy to handle, but he has very little turnout now and is not socialized with other horses except in the ring and horses in the stalls surrounding his.

All depends on how long before the gelding, and also on his temperment. I would assume he'd have to be gelded some time before being shipped, simply because you wouldn't want a horse recovering from the surgery while shipping across the continent.

Due to him being shipped, I would be more inclined to keep him seperate for a little while anyway, just to make sure he adjusts before stressing him out more. If he's been a stallion for 4 years, he may need some time to adjust to living in a herd, so wait until he is acclimated to the totally new environment then start putting him in with other horses.

^^Agreed. I assume that you will be keeping him in quarantine for a certain amount of time anyway so after that, I would say just start introducing him slowly to the herd; give them a connected fenceline for a few days and then see how it goes.

Since he's being shipped from Germany he has to be quarantined in New York for 7 days before we can pick him up. I won't have control over him at that point.

And the fence line part is fairly difficult as none of are paddock, except for the big gelding and mare field are connected. He'll be with the other German boys, a pregnant pony mare/very low mares, and some pony geldings and a foal on the other side of the property, which holds the individual/smaller fields (and even in those they are far enough a part where they can touch noses).

I'm also a little nervous about him getting injured or trying to jump the fence to the girls?

Hmm. Me personally, I would likely just turn him out and keep a close watch for a few hours to make sure he wasn't going to act silly. After that, there isn't much you can do. Most of the testosterone should be out of his system by that time so he shouldn't be terribly interested in the mares, especially if he has never been bred.

I gelded a 4 yo this summer and put him in with my string of saddle horses and he just about left me afoot. There were two mares in there and as soon as one of them came into heat he started chewing up all the other horses. I had to pull him out and keep him seperate for a month or two until the testosterone had left him.

I am no pro here, but I heard that it takes a good 6 months for all the testosterone to get out of their systems!

My after care paperwork from my vet says to not turn them loose with mares for 6 - 8 weeks after the surgery!