Can I get mossy cobble in survival?

I've read that you can get it by leaving cobblestone near or in water for a long period of time... I don't know how long though... Or where to put it exactly

Well you should put one coblestone block next to water but it dosnt work if the water is running or if the coblestone is sarounded by water and once you have one block of mossy coblestone you can make a mossy coblestone farm by outing the mossy coblestone block next to a line of normal coblestone and the put water next to them as long as it is not running it will work .

How long will it take ????

You need to put the cobble stone ( it doesn't matter how you put in at one time) in a large body of water. Then after you need to wait 2 to 3 real life week and then it should be mossy. (Changing the date does not work, you need to wait the entire 2-3 weeks. ;)