How can I keep my cats from jumping over my 6' privacy fence without keeping them on a leash?

Keep them on a leash. The second they leave the yard they can be take to Ac by any one who catches them and you will have to pay fines to get them back. They can also be poisoned or killed by a dog and it will be yoru fault since you didn't keep them leashed

Buy something like a dog run.

I do keep my cat on a leash in my garden, even thou i have a fence. First i can detect where he is, second he is not that agile , so can not just jump and bolt out. He is on his own on a leash when i just sit on swings. I tried once let him without a leash because he doesnt do anything anyway, but then he got into bushes and i couldnt find him and got scared he managed to escape. So now he is always with a leash, runs and chase bumblebees or just sits and sniffs

Unless you install a roller top to the fence or the wire cover that is facing into the yard from the top, you can't keep the cat from going over the fence. Best to build/buy an enclosure that attaches to the house or you can put the cat in there while you are in the yard.

Here is a website for ideas.

http://www.catsofaustralia.com/cat-enclosures.htm

Sorry, not in thier nature to stay put, they will eventually wander. It's what they do.

Build an outdoor catio. Or use those inward hanging netting things.

Starve them till they're too weak to jump? Wow...that's dark. Just keep them indoors.

If its just when you are outside with them, its safer if they are on a harness and lead. That way if something happens, its easy to get them to safety.

Unless you intend to de-claw them, which many consider to be inhumane for cats, there is really no way other than to keep them on a leash. They do make covers that will go on their claws, but I'm not sure if they will keep them from climbing the fence. You may want to ask a vet if there is something you can do.

It's more of a matter of training\obedience. If your cats are driven enough to get over that fence they easily get over it. Cats that are used to having their freedom outdoors are probably untrainable. My indoor cats know to stay within my yard\deck, but they will listen to me when I tell them no when they get close to the fence.