10 minutes Click to see full answer. In this manner, how long does post Mix take to set? 15-20 minutes Also, how much Postcrete do I need per post? you will need minimum 1 bag per post. I usually use one and a half per post but I am using 25kg bags. often poscrete is in 20kg bags so 2 per post is more likely. Considering this, how long does it take for concrete to set in a post hole? 20 to 40 minutes Is 2 feet deep enough for fence posts?The minimum depth that you should dig your fence post holes for panel sections is 2 feet. A general formula is to dig the holes one-third to one-half of the post’s aboveground height. The deeper you dig the holes, the more stability your fence has, but you must also purchase longer posts.
